Final weeds and insects write up for tatenda kangwende

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Tatenda Kangwende

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BLACKFORDBY COLLEGE OF AGRICULTURE GAD17,2014.

STUDENT NAME : TREATISE/PROJECT TITLE : LECTURERS :

TATENDA KANGWENDE WEEDS and INSECTS PROJECT MRS. J. TAPEDZISA and MR. W. MANU

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CONTENTS

PAGE

Acknowledgements…………………….……………………………………….. 1 Objectives……………………………………………………………………… 2 Introduction……………………………………………………………………. 3 Description of broad leaved weeds………………………….............................. 7-22 Description of grass/sedge weeds………………………………………………24-29 Description of poisonous weeds………………………………………………..31-35 Appendix……………………………………………………………………....36-41

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Acknowledgments Best-selling motivational teacher and respected leadership guru John C. Maxwell fittingly quoted a certain Charles Brower, in his work Be A People Person (2007 edition; Cook Communications Ministries; Colorado Springs, Colorado, U.S.A), and had him on record saying that “Few people are successful unless a lot of people want them to be.�(page 181, emphasis that of this student) The sagacious wisdom of the above pithy quote certainly strikes a chord and deeply resonates in the mind, heart and brief life of this student thus far in his human existence and experience. Any success or major accomplishments credited to this student have certainly been the engineering of many a positive conspiracy of professionals from many a field and discipline, as well as dear friends and loved ones. The materialization of this Weeds and Insects Project, which is a significant partial fulfilment requirement for the attainment of a general diploma of agriculture qualification from the respected Blackfordby College of Agriculture is yet another instance of this positive conspiracy at work. From the tireless backing and faithful financial sponsorship of the parents of this student, to the faithful mercies of the Creator God of the Christian Greek and Hebrew Scriptures, this work is the result of many an individual bidding and rooting for the success of this student. He is most grateful for this and formally acknowledges this from the bottom of his heart.

Sincerely

Tatenda Kangwende

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Objectives of this treatise: A warm welcome and manifold thanks to the audience which has gathered to read the contents of this treatise. This Weeds and Insects Project is a mandatory mandated project assigned to all students who enrol for the respected and widely recognized general agricultural diploma program offered by Blackfordby College of Agriculture. The objectives/ main agenda for this mandated project (at least in the eyes of this student) are at least two fold or two pronged in intent, namely: 1. For students to study and gain a keen knowledge and insight on the common weed and insect pests they are likely to face in most husbandry enterprises (at least in Zimbabwe).

2. To be aware and knowledgeable of what remedial (both proactive/preventative and remedial) actions and steps/measures to take so as to eliminate or at the very least, markedly mitigate the baleful threat of these mostly pernicious weed and insect pests.

This student certainly feels that in his opinion, the noble and altruistic objectives/intent of being mandated with the privilege of carrying out this project was fulfilled. This is because if studying is to be defined as the acquisition of useful knowledge through the devotion of time, materials, attention and other resources to that end (Source of paraphrased and italicized definition is pages thirteen and fourteen of Arthur Marara’s work Keys to Academic EXCELLENCE- Practical tools for Examination Preparations ; 2013 Greatness Clinic Trust; Harare, Zimbabwe), then this student feels that he acquired such knowledge through the performance of this mandated project. In the pages to follow, he hopes to demonstrate this much, and, it is hoped that at this treatise’ end, not only will the audience gathered concur with his opinion, but also walk away having learned something helpful and pragmatic to any husbandry enterprise which they may carry out in future. Pleasant and fruitful reading.

With thanks

Tatenda Kangwende

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Introduction “Their hearts are devious; ....They speak mere words, taking false oaths...So lawsuits break out like poisonous weeds in the furrows of a field.”(Hosea 10vs2, 4; Holman Christian Standard Bible Version; ellipses and emphasis are those of this student) Weeds (as are all plants in hopefully a fair and honest opinion) are truly fascinating plants to study. For one thing, there are many a varied but ultimately fascinatingly connected meanings and definitions as to what they are. For instance: 

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The Merriam-Webster free dictionary application for the Android operating system defines a weed as, “a plant that is not valued where it is growing and is usually of vigorous growth; especially: one that tends to overgrow or choke out more desirable plants...”

Helen L. Vukasin et al in their notable work Production Without Destruction (1995, Natural Farming Network Zimbabwe, Harare, Zimbabwe) note that, “A weed has been defined as a plant growing in the wrong place. An alternative definition states that a weed is a plant for which nobody has [yet] discovered a use. These definitions are the key to a sustainable approach to weed management.”(page 88; brackets are those of this student) In the detailed and well laid out lecturing notes of Mrs. Jennifer Mapfumo, nee Tapedzisa (Dip. Agric, Chibero, Senior Lecturer of Crop Production at Blackfordby College of Agriculture; Concession area, Zimbabwe) concerning Weed Science, “[A weed] is a plant that grows where it is not wanted and has certain defined characteristics which make them persistent and harmful to crops.”

All of these sound, correct and lucid definitions shed marvellous light as what weeds exactly are. In short , they are either plants which are not valued or desired wherever they happen to be growing, and/or also, quite often, no profitable use has been discovered or harnessed of them, and, also frequently, they tend to possess certain traits which make them baleful or harmful to the cultivation of desired crops.

Common Characteristics of weeds Another way of approaching the definition of weeds is to simply the follow the line of thought of the truism that, “A weed is as a weed does.” In other words, by simply looking at characteristics common to weed plants, one may get a most correct flavour and hint or inkling as to what they are and do. Below are some of the characteristics of weeds, the vast majority of which are courtesy of Mrs. Mapfumos’ notes, whilst the brief expansion on each point are those of this student:  Weeds are widespread: That is, they are nearly ubiquitous and common as cobblestones.  Weeds are very resilient: That is, they are usually the pioneer plants to emerge in many an altered ecosystem left fallow.

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

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Weeds are notoriously prolific: They set seed and establish large populations very quickly. As one author noted, “One pig weed (Amaranthus hybridus) plant can produce 900,000 seeds, so can you imagine the seed bed produced over a hectare if they are allowed to set seed. We must exercise high standards and make sure that we don’t allow for the weed seed bank to develop, by weeding when weeds are small and never allowing them to set seed.”(Grant Dryden, Farming God’s Way Trainer’s Reference Guide- First Edition; page 113; 2009 Bountiful Grains Trust, Port Elizabeth, South Africa; brackets his) Now that is prolific by any standard. Indeed, according to Mangosho and Mupambwa, several broadleaved weeds such as Ageratum Conyzoides and Chenopodium Album can set seed within forty days of emergence (Integrated Weed Management and Control in Selected Field Crops – A Field Manual for Extension Agents, Trainers, Farm Managers and Researchers; page 4; 2013 Department of Research and Specialist Services, Agronomy Research Institute Weeds Research Team; Mazowe, Zimbabwe) Weeds offer salubrious hideouts and breeding grounds for pests and diseases: For instance, Quelea quelea birds, which can cause considerable yield losses in wheat and barley stands, especially prefer Hyparrhenia species of grasses as a roosting area (Diana E. Taylor, Wheat and Barley; www.pestsandcrops.com/index_files/Page4175.htm#StemBorers; accessed January 3rd, 2014) Weeds are an oft baleful source of toxicity to farm animals: For instance, Lantana Camara is a formidable problem for livestock husband-persons (Lantana Camara Fact Sheet, page 2, courtesy of The State of Queensland, Department of Employment, Economic Development and Innovation, 2011; Queensland, Australia) Weeds are also responsible for much economic loss: It is estimated that in the mighty United States of America alone, crop losses arising from weed pressure are estimated to exceed thirty-five billion dollars, and are equal to the combined losses emanating from insect pests and plant disease. This runs second only to accelerated soil erosion in terms of economic toll and magnitude of the problem (Dale L. Schurter, Mounting Worldwide Crisis in Agriculture; pages 75 to 76; 2013 Restored Church of God, Wadsworth, Ohio, U.S.A). To give one an appreciation of the magnitude of such a staggering figure, thirty five billion seconds covers slightly more than the full time span of a full millennium of roman years.

The above characteristics then, help shed some light on what weeds are, by highlighting some of their more negative traits and proclivities.

Not all bad though: However, it must be duly and fairly pointed out that weeds are not always baleful in effect.

As the saying goes, “There are two sides to every coin”, and this certainly applies to weeds as well, if one may believe it or not. Some effects and traits of weeds are actually good and redeeming; for instance: Page | 4

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

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Weeds provide precious groundcover which helps to mitigate erosion: Since weeds are very vigorous in emergence and growth, they usually help to provide groundcover on otherwise bare and derelict land. This in turn helps to increase the roughness coefficient of a piece of land, thereby reducing its erodibility. This is very useful in the fight against the biggest threat to husbandry and civilization- namely that of accelerated soil erosion and resultant land degradation. How bad is soil erosion and land degradation? Well, according to one husbandperson, “Southern African agricultural lands lose between 55-250 tons or 1000 bags of soil per hectare per year through sheet erosion.” And that,” the African average annual soil loss is around 55 tons per hectare per annum, but it has been proven to be as high as 250 tons per hectare in some regions under conventional tillage.”(Dryden, pages 92 and 94) Some weeds are actually quite edible and a culinary delicacy: This is especially true of the likes of Amaranthus hybridus as well as Bidens pilosa. This student even heard that certain health conscious Seventh-day Adventists boil the Amaranthus hybridus plant, and drink the juice extract, as it is said to have certain health benefits.

Unfortunately, at the time of this writing, this student was not quite able to fully ascertain these claims. One thing is sure though, in Zimbabwe, the aforementioned weeds are consumed.

Weeds (especially those which have not yet flowered) may be used as inputs for surface mulching, green-manuring as well compost making: This helps in ensuring a more closed and efficient nutrient cycle where precious organic matter and nutrients remain on the land (Vukasin et al; pages 78 and 88).

Some weeds can actually be used in crop rotation: Such as the Chloris gayana in rotation with Nicotiana tabacum to both reduce land degradation, as well as reduce pest pressure from root knot nematodes.

Some weeds can be used for effective organic pesticides: For instance, a recipe which makes use of the Tagetes species along with sieved wood ash can be applied to plants affected by aphids with some efficacy. There are also some known organic pesticide recipes for the Bidens pilosa plant as well (Vukasin et al; pages 96-97).

Weeds have many yet presently undiscovered purposes: It could be said essentially then, that weeds are plants whose uses or usefulness have not yet been discovered or acknowledged. This approach in definition is more far-sighted and may yield to future discoveries. Indeed, who knows, perhaps a member of the reading audience may yet discover a useful redeeming purpose for a plant species currently blacklisted as weedy. One author helps to highlight this in an excerpt featured below:

“Purpose of Weeds” “...few seem to realize that weeds have a purpose. In the publisher’s preface to Joseph Cocannouer’s book Weeds,Guardians of the Soil, the publisher summarizes some of the purposes of weeds:

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

“1. They bring minerals, especially those which have been depleted, up from the subsoil to the topsoil and make them available to crops. This is particularly important with regard to trace elements.”

“2. When used in crop rotation they break up hardpans and allow subsequent crop roots to feed deeply.”

“3. They fiberize and condition the soil and provide a good environment for the minute but important animal and plant life that make any soil productive.”

“4. They are good indicators of soil condition, both as to variety of weed present and to condition of the individual plant. Certain weeds appear when certain deficiencies occur.”

“5. Weeds are deep divers and feeders and through soil capillarity they enable the less hardy, surface feeding crops to withstand drought better than the crop alone could.”

“6. As companion crops they enable...domesticated plants to get their roots to otherwise unavailable food.”

“7. Weeds store up minerals and nutrients that would be washed, blown or leached away from bare ground and keep them readily available.”

“Obviously, these purposes and benefits are listed only as general guidelines and do not apply to all weeds under all conditions. F.C. King, in his book The Weed Problem: A New Approach, also revealed that weeds build up and protect the soil and, coexisting with domestic crops, help make soil nutrients more available. The author stated that “we are hopelessly wrong in believing weeds to be useless plants and in devoting our energy to their suppression, instead of studying to employ them.” In England, it has been reported that when lawns become deficient in lime, daisies appear. The daisies are found to be rich in lime, which they manufacture in their tissues. The lime goes into the soil when the daisies die and decay. When the soil becomes sufficiently enriched with lime, the daisy “problem” disappears. When weeds become so abundant that they interfere with crop production, it ought to be recognized that the cause of the problem is not the weeds, but the depleted soil that the weeds were created and designed to protect and build up! Instead of destroying such weeds wholesale with herbicides while our soil continues to be degraded, we need to get busy building up the soil so weeds will naturally reduce themselves.”(Dale L. Schurter; pages 7677; ellipses those of this student) Thus, more and more, it is important to give all weeds a more unbiased assessment as they may yield as yet profitable undiscovered uses.

Happy Reading It is hoped that this brief introduction into what weeds are and some of their purposes and detriments at present will provide a firm footing concerning the subject matter to follow. Many thanks.

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number one: Apple of Peru:

Common name: Apple of Peru Botanical name: Nicandra physalodes Family: Solanaceae General Appearance: Commonly known as gumachembere in Zimbabwe’s chief vernacular language of Shona, Nicandra physalodes’ appearance is characterized by leaves with a particularly wrinkled, fragile look, hence the colourful and apt Shona moniker of gumachembere.

In florescence, the flowers are purple, and, in seedling stage, the cotyledons run opposite each other in almost perfectly straight lines.

Importance: It is said to have repulsive/repellent properties against a number of insect pests.

Mode of action: Besides stressing plants for moisture, nutrients and sunlight, it is also said to be a host of nematodes.

Agricultural importance: A native plant of the South American continent, it is especially most prevalent on heavy textured soils which tend to hold more moisture.

Control method: A pre-emergent herbicide with proven efficacy such as Atrazine should prove adequate in most instances.

(Sources: Mangosho and Mupambwa, page 47; as well as slides 23 and 24 of Mangosho’s Integrated Weed Identification and Management Course 2011; Agronomy Research Institute, Weed Research Team; Mazowe, Zimbabwe)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number two: Black jack:

Common name: Black jack Botanical name: Bidens pilosa Family: Asteraceae General Appearance: Known in Shona as tsine, the Bidens pilosa plant is characterized by a signature deep purple stem that almost qualifies as a shade of black, hence its’ fitting moniker of Black jack.

In florescence, it produces flowers with an almost shouting yellow, and its’ seeds possess characteristic irritating burrs and barbs which easily attach themselves and cling onto hair, Velcro straps and most animal furs. Its’ burs and barbs have been known to be particularly irritating and injurious to sheep .

Agricultural importance: A hardy winter and summer weed.

Control method: An appropriate herbicide for broadleaves; the ideal timing for application is at the pre-emergent stage (or, at the very latest, at a very early post-emergent stage of the crop), and when the weed is in seedling/infantile stage. An example would be the use of Atrazine.

Interesting facts: If mechanically or manually controlled via slashing before flowering stage and laid as a mulch, Bidens pilosa is known to have great efficacy in warding off ants from crop stands. This is important as ants are generally known to be staunch defenders of aphids, which are a most formidable plant pest.

Also, the seeds of Bidens pilosa, when collected, crushed and boiled in sizable amounts in water, can be used to make an organic pesticide which has great efficacy against aphids, cutworms and termites.

Bidens pilosa is also used as an edible vegetable which is loved by many Zimbabweans.

(Sources: Mangosho and Mupambwa, page 19; slides 9 and 10 of Mangosho’s Integrated Weed Identification and Management Course 2011; pages 88, 96-97 of Vukasin et al; as well as slides 6 and 7 of Foundations for Farming’s Natural Remedies presentation; 2013, Foundations for Farming, Harare, Zimbabwe. )

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number three: Bobbin Weed:

Common name: Bobbin Weed Botanical name: Leucas Martincensis Family: Compositae General Appearance: Known in Shona as nyamatumwa, Leucas martinicensis is distinctly characterized by bobbin shaped seed heads; hence the picture perfect apt common name of Bobbin Weed.

Importance: Can be used as a mulch and/or ploughed under as a good source of green manure.

Agricultural importance: This weed is very adaptable and can establish itself in a vast swath of soil types, from the sands to the heavier textured clays. Indeed, this weed finds itself so adaptable and able to establish itself, that it is a common feature on roadsides that have gone into dereliction and where bushy thickets have established themselves. This student obtained the sample seen overleaf on the way to the lush Vumba mountains, circa December 26th, roman year 2013 C.E. Control method: A saving grace of this weed is that, it does not possess as nearly a prolific a seed-bank as say, the Amaranthus hybridus. Thus, even with faithful and diligent cultural practices, such as, say heavy mulching and quick slashing before flowering, the seed bank can be quickly depleted.

(Source: Mangosho and Mupambwa, page 30; Slides 28 and 29 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number four: Dwarf marigold:

Common name: Dwarf marigold Botanical name: Schkuria pinnata Family: Compositae General Appearance: Schkuria pinnata is characterized by an initially yellow color in florescence, which then slowly becomes a light but somewhat strikingly luminescent green.

From afar, the leaves slightly droop and appear a little frayed and fragile, almost like the strands of candy floss.

Mode of action: Can harbour insect pests like leaf hopper.

Importance/Interesting fact: It has been said that this weed can be used to make fragrant perfumes.

Agricultural importance: The weed is characteristically found on light soils, especially where a leguminous crop is grown. This student picked up quite a number of these weeds in a light textured soil with groundnuts. It tends to be a late emerging weed, and can still establish itself with relatively little moisture.

Control method: Pre-emergent herbicides such as Atalachlor tend to have great efficacy against this weed.

(Source: Mangosho and Mupambwa, pages 19 and 51)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number five: Fat hen

Common name: Fat hen Botanical name: Chenopodium album Family: Chenopodiaceae General Appearance: Chenopodium album is characterized by a purplish underside of both cotyledons and true leaves. These same cotyledons and true leaves also possess tiny whitish hairs which tend to give it what one source liltingly terms a “crystalline” or “crystal like appearance”.

Importance: Assertions are that it can be used in traditional flour making.

Agricultural significance: A resilient and entrenched weed, Chenopodium album is found in both light and sandy soils. It is especially infamous for establishing a prolific seed set and deep seed bank. One source and authority is on record noting that a single Chenopodium album plant can produce up to seventy two thousand seeds per plant. That is truly a legion by any standard.

Control method: A good quality pre-emergence or early post-emergence herbicide is ideal, so as to ensure that the weeds do not set seed. Thus, for instance, in Zea mays production, Cyanazine may be used before the two to three leaf stage of the maize plants (seedlings).

(Source: Mangosho and Mupambwa, pages 4, 22 and 47; as well as slides 44 and 45 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number six: Gallant soldier

Common name: Gallant soldier Botanical name: Galinsoga parviflora Family: Asteraceae General Appearance: The true leaves of Galinsoga parviflora have a near trademark shape akin to the spade found in a pack of standard playing cards. In florescence, the flowers are petit and yellow.

Importance: Tradition and hearsay has it that this weed can be added to flavor soups and stews.

Mode of action: Besides siphoning off sunlight, moisture and nutrients, the seed-bank of this week can remain viable in the soil for up to two years.

Agricultural significance: Galinsoga parviflora is characteristically found in heavy soils.

Control method: An effective pre-emergent herbicide should prove sufficient; for instance, in a groundnut stand, Alachlor should be able to do the trick.

(Source: Mangosho and Mupambwa, pages 21 and 51; as well as slides 26 and 27 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number seven: Mexican clover

Common name: Mexican clover Botanical name: Richardia scabra Family: Rubiaceae General Appearance: Richardia scabra possesses white flowers when in florescence. The true leaves of the plant are hairless, and a groove in the center of the leaves provides a near perfect symmetry.

Agricultural significance: This weed signals that a particular soil’s ph is on the low end (that is, acidic). It is characteristically found on more sandy soils.

Control method: A pre-emergent herbicide, such as, say Alachlor should be sufficient in most cases.

(Source: Mangosho and Mupambwa, pages 21 and 51; Page 2 of Mrs. Jennifer Tapedzisa’s Weed Science notes; as well as slides 33 and 34 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number eight: Mexican marigold Common name: Mexican marigold Botanical name: Tagetes minuta Family: Asteraceae General Appearance: Also known as Khaki bos, Tagetes minuta, at seedling stage possesses cotyledons which are similar to those of the Bidens pilosa plant. Generally, the cotyledons of the seedlings are long, but just slightly shorter of those of the Bidens pilosa. At the mature stage, the plant stem is a distinct reddish brown color. Furthermore- and fascinatingly sowhen the leaves and stem of the plant are otherwise rubbed, pressed or squashed together, a strong, somewhat spicy and lingering smell is produced.

Mode of action: Besides fiercely competing for moisture and nutrients with agronomic and horticultural crops, it is asserted that this weed can host nematodes.

Agricultural significance: A common and widespread weed which flourishes when moisture is abundant; thus, it is found both in pastures and arable lands in the rainy season especially.

Control method: It is recommended to apply an early post-emergent herbicide for broadleaved weeds for best success. An example would be the application of Stellar Star when in Zea mays production.

Interesting facts: Tagetes minuta is quite a versatile plant when it comes to viewing a biological or integrated management route with dealing with insect and disease pest pressure.

For instance, soaking a score (twenty) of chopped Tagetes minuta plants (or any member of Tagetes species) in boiled water with sieved wood-ash and applying the resultant tea on plants has been known to ward off aphids as well suppress the more baleful strains of nematodes. When cut before flowering stage, the plants can be used as mulch which can repel nematodes and other pests.

(Source: Mangosho and Mupambwa, pages 18 ; Page 96 of Vukasin et al’s Production Without Destruction ; as well as slides 11, 12 and 13 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number nine: Pigweed

Common name: Pigweed Botanical name: Amaranthus hybridus Family: Amaranthis General Appearance: A generally most easily identifiable weed even at seedling stage, Amaranthus hybridus possesses pronounced veins under-leaf, in conjunction with a fascinating and appealing wine red color on the same under-leaf location as well as the stem.

The seed heads of the plant are also an unmistakeable wine red.

Importance: Can be used as a mulch, green manure, as well as a feed for some animals such as road runners and bantams.

Agricultural significance: In arable lands, Amaranthus hybridus is known to signify that the field in question may likely contain relatively high levels of organic matter.

Control method: Amaranthus hybridus is susceptible to most all common herbicides, and, it can also be controlled culturally, manually and mechanically. All that must be ensured though, is that it is controlled timeously, as it was earlier on noted – if one may vividly recallthat a single Amaranthus hybridus plant can produce almost a million seeds.

Interesting facts: Amaranthus hybridus is widely consumed as a palatable and much loved vegetable. It is known as mowa in Shona. This student also heard it being said that some health conscious individuals boil the plant and the extracted juice may be consumed as a tea which promotes health and acts as a prophylactic of sorts. Unfortunately, this student has not quite been able to ascertain that information.

(Source: Mangosho and Mupambwa, page 29 ; Page 113 of Grant Dryden’s Farming God’s Way Trainers’ Reference Guide- First Edition ; as well as slides 46 and 47 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Weed Number ten: Purslane

Common name: Purslane Botanical name: Portulaca oleracea Family: Portulaceae General Appearance: Portulaca oleracea is a truly unique weed in terms of its appearance; as it tends to fan out and grow in a spreading, sprawling manner. It is also distinctly easy to identify as its’ stem is a faint and conspicuous red; and it possesses particularly succulent stems.

Agricultural significance: If there is anything which the Shona ethnic group/people innately possess in abundance, then it would certainly be the effortlessly colourful and vivid manner in which they name things as they are or do. In Shona, Portulaca oleracea is called Chifandichimuka; and, this refers to the fact that the weed tends to quickly regenerate and reestablish itself if not fully uprooted or dessicated. It is this resilient regenerative or resuscitative power of this weed which is highlighted in that colourful Shona moniker.

Portulaca oleracea is usually found in irrigated arable lands and which also possess high levels of organic matter or inorganic fertilization.

Control method: Strong contact herbicides like Paraquat and Glyphosat may be used, and are recommended to be used at the early seedling stage of the weed’s life, as it is known to successfully withstand low dosages of even such potent herbicides at its more mature stages.

(Source: Mangosho and Mupambwa, page 25 as well as slides 48, 49 and 50 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Weed Number eleven: Sabi morning glory

Common name: Sabi morning glory Botanical name: Ipomoea plebia Family: Convolvulaceae General Appearance: Ipomoea plebia is particularly easy to identify and pick out at early seedling stage as its’ cotyledons are v-shaped. In the weed’s more mature stage, its mature leaves are heart shaped.

Agricultural significance: Ipomoea plebia is generally a harbinger or guidepost that a soil is somewhat loamy or possesses high levels of organic matter. It tends to be found on medium to heavy soils, and in Zea mays production where minimal tillage is being practised.

Control method: Frontier Optima is an excellent pre-emergent herbicide against Ipomoea plebia in both maize and soya bean production.

(Sources: Mangosho and Mupambwa, page 26 as well as slides 7 and 8 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Weed Number twelve: Stockrose

Common name: Stockrose Botanical name: Hibiscus meeusei Family: Malvaceae General Appearance: Hibiscus meeusei is characterized in seedling stage with round cotyledons which remain a signature feature throughout its life. What is more, the true leaves of the plant tend to be characteristically triple lobed.

Agricultural significance: Hibiscus meeusei is normally found in sandy soils, and is a strong indicator that soil phosphorous levels are high. Furthermore, in its’ mid-life stage, it is known to strongly resemble cotton.

Control method: In Zea mays production –and especially after that the crop has followed Nicotiana tabacum in a crop rotation schedule- the pressure of this weed will tend to be greater due to increased phosphate levels. However, given Hibiscus meeusei’s susceptibility to most broad-leaved herbicides, an application of Atrazine at early post-emergence stage should more than suffice.

(Source: Mangosho and Mupambwa, page 23 as well as slides 42 and 43 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Weed Number thirteen: Upright starbur

Common name: Upright starbur Botanical name: Acanthospermum hispidum Family: Alismataceae General Appearance: At seedling stage and early growth stage, Acanthospermum hispidum is characterized by being a light to faintly yellowish green color. The true leaves are generally hairless, whilst the stem is bristly.

Agricultural significance: Acanthospermum hispidum is an adaptable and prolific weed which can easily establish itself in both sandy and clay soils. All these attributes contribute to its’ ubiquity in arable lands; and this has made it Zimbabwe’s third most troublesome weed for some time now.

Control method: If chemical control is to be utilized, then it is wisest and of greatest effect to strike this weed at early seedling stage; as that is when it is most vulnerable/susceptible.

Thus, for instance, if one was growing wheat, one could apply a foliar contact herbicide such as 2.4D Amine 7.2 (Sources: Mangosho and Mupambwa, page 22 as well as slides 35 and 36 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Weed Number fourteen: Wandering Jew

Common name: Wandering jew Botanical name: Commelina bhengalensis Family: Commelinaceae General Appearance: Known as Goche or Gezi in Shona, as well as Trad in Australia, Wandering jew or Commelina bhengalensis has been aptly described by consulted sources as a succulent creeping weed which can choke and smother many a plant. This plant is generally plump and succulent in appearance, with abundant moisture pulsating throughout its stem and veins. At its’ early seedling stage, the leaves emerge and span/fan out from a funnel like center.

Importance/Interesting fact: Said to produce sweet-smelling perfumes.

Agricultural significance: A native plant of South America, Commelina bhengalensis thrives in heavy and moist soils, and can move with dispatch in creeping and establishing a blanket of groundcover which resultantly crowds out and smothers other plants.

Control method: Manual weeding may be utilized, but this needs much diligence and skill as the entire plant –roots and all- must be extracted, else, it quickly regenerates and reestablishes itself. Usually, scorching systemic herbicides like Glyphosat tend to be most potent in combating this weed.

(Sources: Mangosho and Mupambwa, page 25 ; slides 55 and 56 of Mangosho’s Integrated Weed Identification and Management Course 2011; as well pages 1 to 4 of a Biosecurity Queensland fact sheet titled Wandering Jew or Trad http://www.moretonbay.qld.gov.au/uploadedFiles/moretonbay/environment/vegetation/wand ering-jew.pdf Accessed December 29th 2013)

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Weed Number fifteen: Witch weed

Common name: Witch weed Botanical name: Striga asiatica Family: Orobanchaceae General Appearance: Commonly known as Witch weed or Red Witch weed, Striga asiatica is particularly problematic to identify –at least as far as early seedling stage is concerned.

This is because the weed is late in emerging when compared to other weed species, as it will be forming root attachments to its host plant. In florescence though, the weed is much easier to identify as its’ flowers will be of deep, bright and well defined red; as one fellow student and colleague of this individual once aptly noted, the flowers are a “shouting red.” The leaves are also very thin, relatively long and linear.

Agricultural significance: Striga asiatica is a particularly baleful weed as it is parasitic in nature, and preys upon major commercial and staple grain crops such as Zea mays and cane sugar. It is estimated that on the African continent alone, annual damage to all cultivated cereal crops caused by all the species of Witch weed is in excess of seven billion dollars.

This figure also includes increased management expenses, as well as opportunities of lost trade, as grains are difficult to export if they are grown in lands which have been infested with Witch weed.

Generally, the Striga asiatica strain of Witch weed tends to thrive well in nitrogen poor soils, or those which are prone to leaching of nitrates (mainly the sandy soils). This is a major reason why it is quite common in Masvingo province. It also tends to thrive in Zea mays and other cereal crop monocultures, especially when management practices are poor.

Control method: A truly integrated system of control is needed if both Striga asiatica and other strains of Witch weed are to be successfully controlled. The first port of call is to practice a good crop rotation regimen. Mulching of especially more sandy soils will help to reduce leaching of nitrates, and, chemically, Dicamba has been known to be an excellent post emergence herbicide.

(Sources: Mangosho and Mupambwa, page 37 ; slides 98 of Mangosho’s Integrated Weed Identification and Management Course 2011; as well pages 1 to 2 of a Biosecurity Queensland fact sheet titled Pest alert – Red witchweed could be in your area http://www.daff.qld.gov.au/__data/assets/pdf_file/0003/85683/pest-alert-red-witchweed.pdf Accessed January 2nd 2014)

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Weed Number sixteen: Thatch grass

Common name: Thatch grass Botanical name: Hyparrhennia filipendula Family: Gramineae General Appearance: Hyparrhenia filipendula is a perennial grass characterized by hairy and distinct spikelets. It can grow to a height of up to five feet; and the raceme (stalks formed from inflorescence) form a sort of L-shape with the apex of the plant, and hence, it has also been given a colourful informal moniker of “three o’clock thatching grass”.

Importance: Hyparrhenia can be used as livestock feed, and also as a windbreak for brassicas and tomatoes which helps to prevent dessication of the plants.

Agricultural significance: Besides being used in roof thatching, Hyparrhennia filipendula is what is termed an invasive plant species or increaser species of plants; that is, generally, when paddocks are over-grazed, fall into dereliction/neglect, or suffer some form of mismanagement, they become more prevalent (more of a fixture) on the paddock. Generally, this plant is not all that palatable and nutritious to livestock.

Control method: In livestock enterprises holistic herding may be utilized. Holistic herding is a form of intensive herding on paddocks which concentrates livestock on a small portion of a paddock from which they intensively graze for a short period of time before being herded to another block of the same paddock. These intensive bursts of grazing allow for heavy depositions of animal dung and urine as well as the soft scuffling of their hooves on the ground which keeps pastures healthy. Holistic herding was pioneered and popularized by a noted Zimbabwean-American biologist named Alan Savory.

(Sources: articles titled Hyparrhenia filipendula and Hyparrhenia filipendula respectively.

Uniform resource locations werehttp://keyserver.lucidcentral.org/weeds/data/030308000b07-490a-8d04-0605030c0f01/media/Html/Hyparrhenia_hirta.htm and http://www.fao.org/ag/agp/AGPC/doc/gbase/data/pf000257.htm respectively. Both were accessed on February 13th, 2014)

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Weed Number seventeen: Rapoko grass or Goose grass Common name: Rapoko grass or Goose grass Botanical name: Eleusine indica Family: Poaceae General Appearance: Infloresence produces millet like seeds. It is also known to possess a rich/dark green color as well as a pronounced mid-rib.

Agricultural significance: Eleusine Indica, -according to the sources consulted by this student at least- has been blacklisted so to speak, as Zimbabwe’s most abundant/ubiquitous and pestilent weed. It is also infamous for its weed crop mimicry, and it has been said that normally, if one plans to sow millet (rapoko) one should only do so on virgin land, as it can confuse many a husband-person.

Control method: Due to its vigorous rooting, hand or mechanical weeding may prove inadequate. However, it is most susceptible to pre-emergence herbicides. For instance, in commercial Zea mays production, one may apply Alachlor.

(Sources: Mangosho and Mupambwa, page 40 ; slides 66-67of Mangosho’s Integrated Weed Identification and Management Course 2011; as well pages 1 to 4 of an article titled Goosegrass (Eleusine indica) by Greg Breeden, University of Tennessee, Turfgrass Science; http://tennesseeturfgrassweeds.org ; accessed December 30th 2013)

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Weed Number eighteen: Shamva grass

Common name: Shamva grass Botanical name: Rottboellia cochinchinensis Family: Gramineae General Appearance: Possesses a dark red base similar to the reddish purplish color of the stem of Melinis repens (Natal red top). The true leaves are furnished with characteristic/signature stiff and pointed hairs on their upper surface.

Agricultural significance: Following just behind Eleusine indica, Rottboellia cochinchinensis is Zimbabwe’s second most pestilent and baleful weed. The weed is also a general indicator a heavier textured soil, and high soil moisture, as the weed tends to thrive in such conditions.

Control method: It is especially difficult to control in commercial Zea mays production as it is known to detoxify the vast majority of the herbicides used for chemical weed control in that crop. However, it is noted by Mangosho and Mupambwa that an early pre-emergence treatment with Pendimethalin, or, an early post-emergence application of Nicosulfaron should provide proven efficacy.

(Sources: Mangosho and Mupambwa, page 39 ; slides 64-65of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Weed Number nineteen: Wild oat

Common names: Wild oat; Black oat; Bearded oat Botanical name: Avena spp. (especially Avenua fatua) Family: Poaceae General Appearance: Avena spp. Is notorious for its’ weed crop mimicry to Triticum aestivum (Wheat) and Hordeum vulgae (Barley), especially at the seedling stage. However, one distinguishing feature at its’ seedling stage is that the leaves tend to twist. Inflorescence and at mature stage, Avena spp. is characterized by lazily/limply hanging seeds and spikelets, as opposed to waving upright and swaying ears of Triticum aestivum.

Agricultural significance: Avena spp. is a particularly parlous threat when it comes to Triticum aestivum production. Heavy infestations of the weed have been known to reduce yields of the aforementioned crop by up to eighty percent. In Australia alone, Avena spp. infestations annually result in losses to grain crop cultivation/husbandry in excess of $150 million expended in lost production, costs incurred in controlling the weeds, as well as contamination of the cereal crops.

What is more, Avena spp. is also a host to a number of diseases and pests affecting cereal crops, including : cereal cyst nematode (Heteroda avenae), root lesion nematode (Pratylenchus neglectus and P.Thornei), crown rot (Fusarium graminaerum), rygrass toxicity (Rathayifactor toxicus) and rhizoctonia (Rhizoctonia solani).

Control method: Early application of an effective herbicide before inflorescence and seed dispersal is vital in eradicating Avena spp. It is noted that within a window of two to five growing seasons with early chemical control (such as an early-post emergent herbicide like Diclofop-methyl) Avena spp. can be eradicated from one’s crop stands and fields.

(Sources: Mangosho and Mupambwa, pages 41 and 53 ; slide 78 of Mangosho’s Integrated Weed Identification and Management Course 2011; as well as pages 1 to 8 of a document titled Best Management Practices for Dryland Cropping Systems – Wild Oats (Avena spp) , Murrumbidgee Catchment Management authority ; Australia; www.murrumbidgee.cma.nsw.gov.au ; accessed January 5th, 2014 )

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Weed Number twenty: Yellow nutsedge

Common names: Yellow nutsedge or Water-grass Botanical name: Cyperus esculentus Family: Cyperaceae General Appearance: Cyperus esculentus is characterized by a tri-angled stem, and its’ leaves tend to sprawl and spread on the ground.

Importance: Said to be a good alternative feed for pigs if one is stretched for working capital.

Agricultural significance: Cyperus esculentus is an especially troublesome grass weed as it tends to prefer establishing itself in most all tilled lands. Its’ tuber is very resilient and vigorous, and can successfully resist most contact herbicides currently peddled on the market.

Control method: Metolachlor is of great and proven efficacy against the weed as a postemergence herbicide; however, it must be noted that slightly higher dosages of application are needed so as to cater for the weed’s resilient tuber.

(Sources: Mangosho and Mupambwa, pages 45 and 47; slide 54 of Mangosho’s Integrated Weed Identification and Management Course 2011;)

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Weed Number twenty-one: Couch grass

Common names: Couch grass; Bahama Grass or Quick grass Botanical name: Cynodon dactylon Family: Poaceae General Appearance: Cynodon dactylon is a running, untidily sprawling weed with vigorous, extensive rhizomes (sort of pseudo-roots) and stolons (running, spreading growth).

Importance: Can be used to improve roughness co-efficient of contour ridges and so mitigate the erosivity of run-off.

Agricultural significance: Cynodon dactylon is especially problematic when one decides to practice reduced tillage; it also tends to encroach on undisturbed land. It is known to especially aid in providing ground-cover, and in reducing the erodability of abandoned or once barren lands as it improves its’ roughness co-efficient. This weed is also difficult to control, courtesy of its vigorous rhizomes.

Control method: It is best to control Cynodon dactylon with Glyphosate in land preparation stages as it will prove too vigorous for other herbicides to control.

(Sources: Mangosho and Mupambwa, page 38 ; slide 75-76 of Mangosho’s Integrated Weed Identification and Management Course 2011;)

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Weed Number twenty-two: Thorn apple

Common names: Thorn apple, Stink blaar, Jimsonweed Botanical name: Datura stramonium Family: Solanaceae General Appearance: Datura stramonium is characterized by jagged leaves and trumpet shaped flowers. It also possesses a crimson stem, and, as its’ fitting common names of stink blaar and thorn apple suggest, the fruit of the weed is spiked and thorny, and it’s stem, when smelled, exudes an obnoxious, pungent odor.

Agricultural significance: The seeds and leaves of Datura stramonium are poisonous, as they contain a chemical/drug known as hyoscyamine; in humans, heavy dosages of this drug can cause nausea, resultant vomiting and dizziness. The presence, element of this drug/poison makes Datura stramonium particularly baleful to livestock.

Control method: Datura stramonium is easily controllable mechanically (for instance, through deep ploughing and harrowing during land preparation stages). Various broadleaf herbicides are also effective against Datura stramonium; for instance, in Glycine max production, one may apply Bentazon as a post emergence herbicide, usually at a rate of three liters per hectare.

(Sources: Mangosho and Mupambwa, page 9, 27 and 50 ; slide 18 of Mangosho’s Integrated Weed Identification and Management Course 2011; as well as an article titled Hyoscyamine http://www.nlm.nih.gov/medlineplus/druginfo/meds/a684010.html ; accessed February 8th 2014)

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Weed Number twenty-three: Lantana camara

Common names: Lantana Botanical name: Lantana camara Family: Verbenaceae General Appearance: One source notes that “Lantana is a heavily branched shrub that can grow in compact clumps, dense thickets or as a climbing vine.” The stems are also quite prickly at times, and, the true leaves possess a rich, dark and well defined green color; they are also rough-edged as well. Lantana camara also tends to produce “round, berry-like fruit that turn from glossy green to purplish black when ripe.”

Importance: Can mar tourist destinations. For instance, (circa roman year 2010 C.E.) a concerted effort was undertaken in the resort town of Victoria Falls to eradicate the weed.

Agricultural significance: Lantana camara is a most vigorous, poisonous and invasive weed, especially hamstringing the viability of livestock enterprises. In Australia alone for instance, that nation’s eastcoast is known to have five million hectares of its’ land affected by the weed, which, annually costs its’ economy over $70 million in lost agricultural production.

Containing a chemical known as Lantanadene, this poison adversely affects cattle, sheep and goats the most. In these animals, normal liver function is hamstrung, resulting in poisoned animals losing condition and general health. Typically, the poisoned animals become photosensitive, develop fever, suffer from shortness of breath, as well as evidence dry and cracking muzzles. Prolonged and sustained poisoning results in death of the poisoned animals.

Control method: Chemical control with scorching herbicides such as Roundup and Tordon is very effective. Also, continued and sustained stumping of the plants will result in them losing their vigor to re-grow.

(Sources: Direct quotations taken from page 1 of a document titled Lantana published by The State of Queensland, Department of Employment, Economic Development and Innovation, in 2011 http://www.moretonbay.qld.gov.au/uploadedFiles/moretonbay/environment/vegetation/lantan a.pdf accessed December 29th, 2013; general information on the weed obtained from the same source; as well as pages 34 and 35 of Animal Health and Diseases notes compiled by Raphael Phiri (Diploma in Agriculture from Blackfordby College of Agriculture; Concession, Zimbabwe)

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Weed Number twenty-four: Purple garden sorrel

Common name: Purple garden sorrel Botanical name: Oxalis latifolia Family: Oxalidaceae General Appearance: Characterized by three butterfly-like leaves (and also appearing somewhat like a four leaf clover) Oxalis latifolia possesses no stems, but rather petioles (sort of pseudo stems in a sense). This weed is succulent, and its inflorescence is characterized by purple flowers, hence its’ befitting moniker of purple garden sorrel.

Interestingly, this weed is also known as salt weed, and, in the shona language, it is known as chimunyu. These alternative names in the mentioned respective languages are due to the weed possessing a savory/salty taste when one of its’ petals are chewed.

Agricultural significance: Oxalis latifolia lacks true roots, and, propagates through its’ basal bulb. This same basal bulb causes the plant to be succulent as well as grow most vigorously.

This key characteristic makes this weed almost impervious to most forms of mechanical control.

Control method: Herbicides specific to bread-leaved weeds are best. Thus, for instance, if one is to cultivate field beans, they could make use of a pre-emergence herbicide such as Clomazone, at a rate of approximately two liters per hectare.

(Sources: Mangosho and Mupambwa, pages 24 and 52; slides 40 and 41 of Mangosho’s Integrated Weed Identification and Management Course 2011)

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Weed Number twenty-five: Bitter apple

Common name: Bitter apple Botanical name: Solanum intortum Family: Solanaceae General Appearance: Solanum intortum is a woody, hardy type of weed with sharp thorns on its stems. It is characterized by alternating slender and relatively lengthy and slightly eggshaped leaves with green and globular stems.

Agricultural significance: Solanum intortum is particularly troublesome in livestock production as it is toxic to livestock (namely cattle, sheep and goats). It is also an encroaching and invasive weed. It is baleful in its’ effect in that it is known to poison wild herbivores in East Africa.

Control: Heavy and thorough weeding as well as the use of a scorching herbicide (especially during its’ early stages of growth when it is not as woody) such as paraquat are the most effective methods of control.

(Source: article titled Sodom Apple keys.lucidcentral.org/keys/v3/eafrinet/weeds/key/weeds/Media/Html/Solanum_incanum_(Sod om_Apple).htm accessed on February 3rd 2014)

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Weed Number twenty-six: Large cocklebur

Common name: Large cocklebur Botanical name: Xanthium strumarium Family: Asteraceae General Appearance: Xanthium strumarium is a profusely branched weed which can grow up to four feet tall. Its’ fruit or burs are ovoid in shape, and are dotted with tiny spines throughout their outer surface.

Agricultural significance: Can be troublesome to agronomic crops such as Zea mays and Glycine max. Xanthium strumarium is also known to be invasive to pastures where it is toxic to livestock. In South Africa it has been declared as a noxious weed, and thus, by law, control is mandatory on the sighting of this weed.

Interesting fact: Whilst a yellow dye can be extracted from Xanthium strumarium its’ harmful effects currently far outweigh the known potential economic benefits this weed exacts on a nation’s economy.

Control method: A scorching pre-emergent herbicide such as glyphosat is best .

(Source: article titled Xanthium strumarium keys.lucidcentral.org/keys/v3/eafrinet/weeds/key/weeds/Media/Html/Xanthium_strumarium_( Large_Cocklebur).htm accessed February 3rd 2014)

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APPENDIX

TABLE 1): DISEASES AND PESTS HOSTED BY WEEDS WEED

PESTS

DISEASES

1

Apple of Peru.

Eelworm and ladybird (a beneficial insect)

Bacterial leaf spot.

2

Black jack.

Grass hopers.

Mold.

3

Bobbin weed.

Stink bug and thrips.

Scab, powdery mildew and rusts.

4

Dwarf marigold.

Thrips and semi looper.

Leaf-spot.

5

Fat hen.

Wireworm.

Downy mildew.

6

Gallant soldier.

Spider mites.

Leaf spot.

7

Mexican clover.

Caterpillar.

White rust.

8

Mexican marigold.

Assassin bug and leaf miner.

Dic back.

9

Pigweed.

Locust and bugs.

Leaf spot.

10

Purslane.

Caterpillar.

White blisters.

11

Sabi-morning glory

Semi-looper.

White rust.

12

Stockrose.

White fly and thrips.

Leaf spot.

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13

Upright starbur.

Red spider mites and aphids.

Powdery mildew and leaf spot.

14

Wandering jew.

White grub.

Rust.

15

Witch weed.

Aphid eelworm (melidogyne javanica).

Leaf and stem blight.

16

Hyparrhenia spp.

Locust.

Ear blight rust and smut.

17

Rapoko grass.

Grasshoppers and locusts.

Mosaic, chlorotic and streak and rust.

18

Shamva grass.

Grasshoppers and locusts.

Leaf spot and rust.

19

Wild oat.

Aphids and leaf hoppers.

Halo blight and powdery mildew.

20

Yellow nutsedge.

Wireworm and nematodes.

Tar spot rust.

21

Couch grass.

Locusts and grasshopper.

False edged and leaf spot.

22

Love grass.

Termites, grasshopper and locusts.

Fungus smut and leaf spot.

23

Panicum spp

Leaf mine assassin bug and semi looper

Leaf spot and late blight

24

Purple nutsedge.

Wireworm and nematodes.

Tar spot rust.

25

Rhodes grass.

Termites and white ants.

Leaf blight and leaf spot.

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26

Thorn apple.

Locusts, leaf miner and assassin bug.

Late blight.

27

Lantana camara.

Leaf hopper.

Stem rot.

28

Oxalis spp.

Stink bug.

Rust.

29

Solanum intortum.

Semi-looper.

Rust.

30

Cocklebur.

Stinkbug.

Rust.

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TABLE 2): SUMMARISED TABLE OF WEEDS THAT INDICATE SOIL TYPE, CLIMATE AND VELD CONDITIONS WEED NUMBER

WEED NAME

SOIL TYPE

CLIMATIC CONDITIONS

VELD CONDITIONS

1

Apple of Peru.

Heavy to light soils.

Cool to medium temperatures.

2

Black jack.

Tolerates all soil types.

Low, medium and high temperatures as well as rainfall.

Waste lands, irrigated field, gardens and dam sides.

Disturbed lands gardens, arable lands and roadsides.

3

Bobbin weed.

Clays.

Moderate rainfall.

Mild.

4

Dwarf marigold.

Sandy clay loams, Sandy loams and medium textured soils.

Medium rainfall.

Disturbed lands, gardens and arable lands.

5

Fat hen.

Sandy and clay soils.

Cool temperatures to warm.

Irrigated lands, gardens and arable lands.

6

Gallant soldier.

Medium to heavy textured soils.

All temperatures and tropical areas.

Garden lands roadsides pastures and arable lands.

7

Mexican clover.

All soil types.

Tolerate all temperatures as well as rainfall.

Disturbed lands roadsides pastures and arable lands.

8

Mexican marigold.

Usually in sandy clay, sandy loam, sandy.

Low to medium altitudes with varying rainfall.

Waste lands disturbed lands, bare fallows and arable lands.

9

Pig weed.

Light to heavy textured soils with manure.

High to low altitudes with varying rainfall.

10

Purslane.

Sandy loam to heavy clays.

High to medium rainfall patterns.

Disturbed lands arable lands, cultivated fields and roadsides.

Irrigated lands.

11

Sabi-morning glory.

Sandy loam, loam and clay.

Medium to high rainfall pattern.

Most arable lands.

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Stockrose.

Sandy soils.

Low to high rainfall patterns and medium to high altitudes.

Waste lands disturbed land and roadsides.

13

Upright starbur.

Sandy soils.

Arable lands and disturbed lands.

14

Wandering jew.

Sandy clay to medium ranging soils.

Low to medium altitudes with a varying rainfall pattern.

High altitudes with high rainfall patterns.

15

Witch weed.

Soils lacking nitrogen to poor soils.

Any weather in which maize, sorghum and millet thrive.

All fields where sorghum, maize and millet are grown.

16

Hyparrhenia spp.

All types of soils.

Occurs in open lands and arable lands.

17

Rapoko grass.

All soil types, especially light soils.

Warm and moderate rainfall as well as shorter dry season.

Moderate altitude and moderate to high rainfall.

18

Shamva grass. Heavy soils that are fertile.

High rainfall and high to medium altitude.

19

Wild oat.

Fertile and irrigated soil.

Warm and temperate.

Disturbed soils.

20

Yellow nutsedge.

Both warm and cool temperatures.

Gardens, disturbed lands and damp soils.

21

Couch grass.

Sandy clays, sandy and sandy loam with frequent moisture.

Clay loam and sandy loam.

Average rainfall.

Cultivated and disturbed lands.

22

Love grass.

Clay loam and sandy loam.

Average rainfall.

Cultivated and disturbed lands.

12

Cultivated lands, disturbed lands and pastures.

All disturbed lands roadsides, pastures gardens and manure fields.

All cultivated and disturbed lands.

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23

Panicum spp.

Clay.

Medium rainfall.

Along roadsides cultivated and disturbed lands.

24

Purple nutsedge.

Sandy loam with frequent moisture.

Both warm and cold temperatures.

Gardens, disturbed lands and damp soils.

25

Rhodes grass.

Moderate to high rainfall.

Arable lands woodlands and grasslands.

26

Thorn apple.

Clay loam medium fertile soils with a Ph range of 6-8.

All soil types.

27

Lantana camara.

Dam soils, disturbed lands and arable lands.

Pastures, riversides waste lands and bare fallows.

28

Oxalis spp.

29

Solanum intortum.

Wide ranging soils but not so good with heavy textured soils.

Moist soil but favors heavy textured ones most.

Light medium and heavy clay.

Varying altitudes with different rainfall patterns.

Ranges from medium to high rainfall patterns on varying altitudes.

Tolerate moist conditions.

Occurs readily in tropical regions.

Road sides and disturbed lands.

30

Cocklebur.

Sandy soil.

Areas of high sunlight.

Arable lands, pastures and disturbed lands.

Gardens and green houses.

(Source of summarized tables: Mangosho and Mupambwa).

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CONTENTS PAGE Introduction……………………………………………………………………………….44 DESCRIPTION OF EACH INSECT Aphid……………………………………………………………………………………..48 Budworm………………………………………………………………………………....51 Cotton stainer………………………………………………………………………….....54 Cutworm………………………………………………………….....................................56 Diamondback moth……………………………………………………………………….58 Ladybird beetle…………………………………………………………………..………..60 Leafhopper………………………………………………………….…………….............62 Locust…………………………………………………………………………………….64 Maize stalk borer…………………………………………………………………………66 Red bollworm…………………………………………………………………………….69 Semi looper……………………………………………………………….........................71 Spider mites………………………………………………………..……………………..74 Stink bug………………………………………………………………………………….76 Thrip………………………………………………………………………………………79 Wasp………………………………………………………………………………………81 Key to Insect specimens supplied…….…………………………………………………………………………...83

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Introduction: Fascinating Insects “All things bright and beautiful,’ ‘All creatures great and small,’ ‘All things wise and wonderful:’ ‘The Lord God made them all.”(Source: A hymn penned by Cecil F. Alexander, titled All Things Bright and Beautiful: http://library.timelesstruths.org/music/All_Things_Bright_and_Beautiful/ accessed December 30th 2013) According to the Merriam-Webster lexicon application for the Android operating system, an insect is, “any of a class (Insecta) of arthropods (as bugs or bees) with well-defined head, thorax and abdomen, only three pairs of legs, and typically one or two pairs of wings.”(entry, “Insect”).

Insects are a truly fascinating branch of animal life which are a vast, near limitless universe unto themselves. “What? A vast and near limitless universe unto themselves?” One may ask within him or himself. Indeed, this is so; for instance, did one know that:     

The exact number of insect species extant on planet earth is not entirely/assuredly known.

There are currently at least eight-hundred thousand to a million documented species of insects.

Annually, at least ten thousand additional species of insects are formally documented and classified annually.’

The known number of insect species is more than the aggregate of species of all other known species of animal life.

Circa roman year 1960 C.E., planet earth’s human population reached the three billion mark; and, in late roman year 2011 C.E., earth’s human population surpassed the seven billion mark.

Now then, using the seven billion mark reached in late 2011, the human population density per square mile of land area on planet is approximately one-thousand two-hundred and seventeen people per square mile. Well, this figure of human population density, pales into insignificance when compared to insect population density, where, in every square mile of earth’s land area, one would find, on average, some three billion insects (the same number of all human inhabitants at the beginning of the 1960’s)! (Source: Dale Schurter Mounting Worldwide Crisis in Agriculture; page 67; 2013, Restored Church of God, Wadsworth, Ohio, United States of America) Some truly mind boggling statistics to say the least; and all of them contribute to bolstering the claim that the world and universe of insects is almost beyond the scope of even the most fertile and active of imaginations.

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A beneficial universe Indeed, the sheer number of insect species, and the populations of their constituent members, accrues many a benefit to humankind. For instance, some of the benefits which have come to humanity gaining an increased appreciation of what insects can do for it when harnessed well, include, but are definitely not limited to: 1) The fact that insects are indispensable pollinators of cultivated plants without which humanity’s vast number and population would almost certainly be decimated, or, in the very least, be drastically reduced.

2) Many insects are a direct and palatable source of nutritious food: For instance, the New Testament Christian Greek Scriptures record that John the Baptist ate locusts and honey (one may consult chapter three of Matthew’s Gospel to see this documentation)

3) Insects provide useful and beneficial material to humankind: For instance, honey bees provide honey for the culinary and prophylactic delight of many a member of the human race.

4) Many insect species improve the diversity and health of ecosystems: For instance, dung beetles increase the porosity, drainage and overall structure of the soils privileged to have them.

5) Many sages and observant humans have derived much wisdom and pragmatism from the way insects go about their business: For instance, in the biblical book of Proverbs, ancient Israelite monarch, King Solomon advises one to take a cue and practical life lesson from the motivation, initiative and diligence exhibited by the humble ant. (see Proverbs 6vs6-11) 6) Insects contribute to innovative solutions in technology, science and design: Increasingly – and very astutely-technologists, scientists and all levels of designers and engineers are looking first and foremost towards nature (especially bio-organisms) for ideas and guidance in coming up with viable solutions to all manner of pressing problems.

This approach of looking to nature and the biosphere in particular for pragmatic and workable technology, science and design solutions is known as bio-mimicry. One prominent engineer and scientist likened Page | 45

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biomimicry to looking into nature’s research and patent catalogue, and making good use of it (Source: Michael Pawlyn in a talk of his titled Using nature’s genius in architecture http://www.ted.com/talks/michael_pawlyn_using_nature_s_genius_in_ architecture.html ; accessed February 21st 2011 ). One instance of the use of bio-mimicry, was in the construction and design of the Eastgate shopping mall and office building complex which is situated in the nation of Zimbabwe’s metropolis of Harare (the shopping mall and complex- at least at the time of this writing, also houses some of the offices of the consulate of the mighty United States of America). This building is widely lauded as being one of the most energy-efficient edifices in the world. It was constructed and patterned after the design of anthill and termite mounds, after it was noted that such structures remain so cool and habitable even in the harshest and driest of desert climates. The principles used in the design of these natural structures was then transferred into the design of this energy efficient building, which economizes on the use of air-conditioning for cooling, and thus, energy use.

Thus, insects contribute immensely to humanity’s progress.

Only a minority are pests A correct and pithy truism notes that there are two sides to every coin, meaning that most everything has its pros and cons. Well, the same applies to the world and universe of insects; because, whilst they do yield many a benefit to humankind, a tiny, tiny minority are unfortunately currently pestilent to humanity. In fact, only half a percent (that is, only 0.5%) of all known insect species are pestilent to humanity (Schurter, page 67), thus, on the whole, insects are far, far more of an asset than a liability to humanity.

For instance, just two of the ways in and through which the tiny minority of insect species are pestilent to humanity include: 1) Reduction in both quality and quantity of agricultural crop yields: Annually, at least one fifth of the world’s crop production is lost to insect pests (ibid) 2) Resultant huge economic loss: In 1973, the United States Department of Agriculture estimated that in that year alone (namely of roman year 1973 C.E.), economic losses attributed to insect pests was between four to five billion dollars, whilst production in that year was nearly thirty-billion dollars.

Integrated Pest Management is needed:

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In order to deal with the tiny, tiny minority of currently pestilent/blacklisted insect pest species, it is important that a long-sighted and holistic view/outlook is adopted. This will involve the use of more eco-friendly land preparation and husbandry practices, the use of natural pest predators, and even more applied research and development, which may one day even find useful applications of some of the insects which today are vilified as pests, but could well be harnessed to yield a benefit to humankind. It is hoped that this treatise will contribute to this discussion. Many thanks to the audience gathered to read it.

Sincerely Tatenda Kangwende

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Insect number one: Aphid Scientific name(s):

A) Brevicoryne brassicae B) Myzuz persicae C) Lipaphis erysimi

Type: Sap-sucking pest (nymphs and adult) Hosts:

1) Brassicas 2) Beans 3) Tomatoes

Order: Hemiptera Common names:

A) Cabbage aphid B) Green peach aphid C) False cabbage aphid

Appearance: Aphids are small-bodied, pale greenish to silver colored winged insects which characteristically group/huddle together on crop leaves and stems, especially on the underside of the leaves of brassicas.

Damage: Aphids cause baleful harm to plants, especially in the following ways: a) Through their sap-sucking when feeding: They can cause curling of affected plant leaves, thereby reducing the plant’s photosynthetic area. This results in plants becoming stunted, and, in extreme cases, deformed, causing the affected plants to become completely unmarketable. b) The wasteful nature in and through which they feed: The profligate (wasteful) manner in and through which they feed results in aphids excreting a substance known as honeydew (excess sap composed of sugary solutes and other substances). When this substance lands on lower plant leaves, the impacted areas are usually blackened as a result of a salubrious environment being provided for mold causing fungi. c) They are infamous vectors of plant viruses: Aphids acquire virus pathogens when feeding on infected crops, and, subsequently, pass on the virus to other plants as they feed on them. An example of one such virus which they spread is that of Cauliflower Mosaic Virus. Severe cases of the virus can cause severe leaf mottling (that is, spots or blotches), and result/culminate in reduced leaf size and compromised function.

Lifecycle: “Aphid life cycle” “During the summer months, the aphid continues to produce wingless daughters by a process called parthenogenesis; the production of offspring without the involvement of sex. From time to time, winged daughters are produced and these fly away to colonise new Page plants. | 48 In the Autumn the winged individuals include males.”

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“The males fly off to a woody shrub or tree and are joined by winged females. Here the females produce wingless daughters which are mated by the males and then lay hard-shelled eggs on the tree branches.

In this form the aphids survive the winter. “

“In Spring the eggs hatch to wingless females which produce winged daughters by parthenogenesis. The winged daughters fly to the plants on which they will feed and establish new colonies.”

Simple Aphid Lifecycle Diagram

Source of information: © D.G. Mackean (Source of Lifecyle information (both text and diagram) was: http://www.biology-resources.com/documents/aphid-p2-life-cycle.doc accessed February 4th 2014

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Control: a) Good management and cultural practices such as refraining from over-application of nitrogenous chemical fertilizers coupled with the liberal use/application of welldecomposed organic manure will ensure that plants have a fighting chance of being less prone to aphid attack, as they will not exhibit rank growth and succulence, which, only serves the end of making them more susceptible to aphid infestation. b) Where possible, one should utilize an overhead irrigation regimen, as this tends to lower aphid numbers. c) One may also consider using strong repellent plants (such as Tagetes minuta, which is commonly known as Mexican marigold )as a mulch, as this tends to have a repulsive effects on aphids. d) One may also consider inter-planting with onions and/or garlic, as these horticultural crops do also tend to repulse aphids. e) The use/application of a soapy water solution (usually a mixture/ration of 1:25, namely of soap and water respectively) will help to wash off and smother the aphids on infested plants.

(Source of information: Hans Dobson et al, Integrated Vegetable Pest Management – Safe and sustainable protection of small-scale brassicas and tomatoes:- A handbook for extension staff and trainers in Zimbabwe; 2002, Plant Protection Research Institute; Harare, Zimbabwe; pages 70-72, 91-92, 163)

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Insect number two: Budworm Scientific name:

Hosts:

Heliothis virescens

1) Tobacco 2) Spruce 3) Petunia 4) Others…

Order: Hemiptera Common names: 1) Budworm 2) Tobacco budworm.

Appearance: Larvae are usually a quarter to half inch in length, and possess the uncanny ability to almost “match” the color of their host plant, thereby making them nearly imperceptible. However, as one source notes, “Unfortunately, their damage is [all] too easy to notice.”(Source: article, Budworm control http://bugspray.com/budworm-control.html ; accessed December 29th 2013; brackets are those of this student.)

Damage: Budworms ravish and particularly enjoy consuming flowering buds, though they can easily feed on all parts of the host plant; and, when this occurs, the plant’s demise is likely imminent.

Lifecycle: The most destructive stage of this pest’s lifecycle is its larval stage. The larvae find their origin from adult moths which usually linger around host plants which they have sighted/targeted. On such targeted plants, female specimens will lay eggs which hatch some two to five days later. Small caterpillars will emerge from hatched eggs and feed for some two to three weeks.

Once satisfied, the caterpillars will migrate to the soil and pupate for some two to three weeks, after which they will emerge as adult moths to recapitulate the aforementioned cycle.

Simple Lifecycle Diagram

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Source of lifecycle diagram: https://insects.tamu.edu/students/undergrad/ento402/Cotton_files/Cotton_popup/Heliothis_life.jpg Accessed December 30th 2013

Control:  

Encourage the presence of parasitoid wasps through allowing and/or cultivating dill and/or fennel.

Handpicking and squashing of caterpillar larvae is also an effective method on small acreages.

(Sources of information: Article titled Budworm Control http://bugspray.com/budwormcontrol.html ; acessed December 29th 2013; as an article titled Tobacco Page | 52

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budwormhttp://entnemdept.ufl.edu/creatures/field/tobacco_budworm.htm ; Accessed February 16th 2014)

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Insect number three: Cotton Stainer Scientific name: Hosts:

Oxycarensus hyalipennis (dusky cotton stainer)

1) Baobab 2) Sterculia 3) Cotton

Order: Hemiptera Common name: Cotton stainer.

Appearance: Cotton strainers usually sport a bright red as well as black color. They typically reach up to one, to one and a half centimeters in length. A key/ almost trademark characteristic of this insect is to see it running back and forth in mating pairs attached back to back. The adults also tend to fall to the ground when disturbed.

Damage: One authority notes the following very well: “Stainers are a late season pest, and they cause mechanical damage by inserting their long proboscis into the developing bolls to feed on the seeds. They may render the seed sterile or at least reduce germination percentages by their feeding, but this would not be serious unless the crop was being grown as a seed crop. However, they cause indirect damage by injecting spores of a fungus known as Nematospora. If this occurs while the bolls are still small, they may be dropped by the plants, but older bolls (3-4 weeks old) become badly stained by the fungus, with spoiled lint of inferior quality. More mature bolls may be less affected by the infection.� (Source of information: Diana E. Taylor Cotton Stainer http://www.pestsandcrops.com/index_files/Page2083.htm accessed December 29th 2013)

Lifecycle: Adults mate, after which large orange eggs are laid in batches of a hundred or so in moist soil. The eggs hatch not long after, and undergo an incomplete metamorphosis of five nymph stages en route to adulthood. Feeding is most pronounced between the second and fifth nymph stages with latter instar nymph stages usually spreading/fanning out further afield in search of fruits and seeds on which to feed. Second instar nymphs are usually more congregational in feeding habits.

The nymph stages usually take a month in warmer summer temperatures, and, is retarded/far slower in wintry months. Adults tend to be mobile flyers and migrate to host plants.

Simple Lifecycle Diagram of cotton stainer

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Source of picture of lifecycle: http://www.brisbaneinsects.com/brisbane_bugs/images/Buglif6.gif Accessed February 3rd 2014

Control: 



The major control method in Zimbabwe is to adhere to the legislated cotton planting and destruction window dates/periods; this helps to greatly reduce pest numbers.

In cases of small infestations occuring on smaller acreages, hand-picking and squashing is a possible/feasible and effective option.

(Source of information: Diana E. Taylor Cotton Stainer http://www.pestsandcrops.com/index_files/Page2083.htm accessed December 29th 2013)

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Insect number four: Cutworm Scientific name(s):

Agrotis spp.

Type: Chewing pest.

Hosts: 1) Brassicas. 2) Beans. 3) Tomatoes. 4) Pepper and onions. 5) Groundnuts. 6) Other plants.

Order: Lepidoptera.

Common names:

A) Cutworm.

B) Black cutworm.

C) Green cutworm.

Appearance: Cutworms are the caterpillar stage of the noctuid moths. The adult moth is grey-brown in color, whilst the harmful caterpillars are smooth textured (that is, in terms of their skin), grayish black in color, and, manifest the proclivity of coiling up into a C-shaped figure when handled/disturbed.

Damage: Cutworms make clean cuts/incisions at the very base of plant stems (especially of plant seedlings, and thus often cause lodging of transplanted plant seedlings. Those plant seedlings which do not lodge, often tend to wilt due to a damaged/compromised vascular bundle.

Lifecycle: Adult noctuid moths lay whitish yellow eggs on host plants at night. The laid eggs increasingly darken as hatching becomes more imminent.

It is at the larval stage that damage is done to host plants, as the caterpillars emerge at night, make incisions on the plants, and drag their food into the soil so as to feed on it during the day.

Finally, the larvae pupate in the soil‌ Simple Lifecycle Diagram

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Source of information concerning Cutworm lifecycle: http://uspest.org/ipm/vc_stg.gif Accessed February 3rd 2014

Control: 

  

Cutworms tend to thrive in weedy/weed infested areas, thus, thorough land preparation before planting or transplanting (preferably at least two weeks before such an action) should be carried out.

It is also noted that flooding before transplanting seedlings helps smother/suffocate cutworms resident in the soil at that juncture.

Handpicking and crushing of the pests shortly after transplanting is also a highly effective technique on small acreages.

Bantams and/or other breeds of chickens circulated in A-frame/portable chicken runs may be used as land preparation on small acreages or garden plots. Not only do they enjoy consuming the pests, but their claws excellently till and aerate the soil as well.

They also deposit rich nitrogenous manure.

(Sources of information: Hans Dobson et al, Integrated Vegetable Pest Management – Safe and sustainable protection of small-scale brassicas and tomatoes:- A handbook for extension staff and trainers in Zimbabwe; 2002, Plant Protection Research Institute; Harare, Zimbabwe; pages 99-100; as well as Vukasin et al’s Production without Destruction 1995 Natural Farming Network Zimbabwe, Harare, Zimbabwe; pages 92, 160-161)

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Insect number five: Diamondback moth Scientific name:

Plutella xlostella

Type: Chewing pest (larvae) Hosts:

1) Brassicas 2) Aubergine 3) Mustard

Order: Lepidoptera Common names:

A) Diamondback moth B) DBM C) Cabbage moth

Appearance: Adult specimens are moths which fold their wings along their back. The moniker “diamond back moth” stems from the fact and fascinating distinguishing feature of markings on the wings of male specimens which, together, appear as three diamond shapes which are pronounced on a brown background/backdrop.

Damage: The bulk of the damage is caused by larvae at different instars. First instar larvae usually mine in the leaf itself and, emerge from the underside. Older larvae feed on all other plant parts. The cardinal sign of their damage and harmful presence is transparent patching of the upper leaf surface which then develops into a full-blown hole. This effect is known as windowing.

Lifecycle: Females lay yellow eggs on the leaves of host plants, which then hatch into green caterpillars (larvae) some three to five days later. The larvae undergo four more instars before pupating inside a silk cocoon attached to either one of the host plant’s leaves or its’ stem.

Adults eventually emerge from the cocoon, and female adult specimens usually commence on the day of emergence. First instar and latter instar larvae tend to be the most threatening stage(s) of this insect pests’ lifecycle.

Simple Diamondback moth Lifecycle Diagram

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Source of information: http://uspest.org/ipm/vc_stg.gif ; accessed February 3rd 2014.

Control: 



  

Good timing and integration of operations can help to utilize nature to one’s own advantage in dealing with this insect pest. For instance, planting in the rainy season can help reduce the numbers of this pest as its’ young larvae tend to be washed off.

An overhead irrigation regimen also has the same effect.

On small plots of land, handpicking and squashing of larvae can also be a workable and effective solution. One method of identifying the larvae of this moth is that, when disturbed, they tend to curl up or suspend themselves on silk threads.

Crop rotations with non-host plants (example, sweet-corn) will help starve the moths and larvae as they tend not to be very mobile.

Mustard can be planted as a trap crop, and then, once attacked, it can be removed.

One may pick up diseased DBM larvae (usually plump, bloated and yellowish in appearance), crush them, mix the juice with water, and spray it on infested plants. The pathogens in the juice will then adversely affect and eventually destroy the healthier larvae resident on the other plants.

(Source of information: Hans Dobson et al, Integrated Vegetable Pest Management – Safe and sustainable protection of small-scale brassicas and tomatoes:- A handbook for extension staff and trainers in Zimbabwe; 2002, Plant Protection Research Institute; Harare, Zimbabwe; pages 62-65)

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Insect number six: Ladybird beetle Scientific name: Coccinella septempunctata Family: Coccinellidae Order: Coleoptera Common names:

A) Ladybird beetle B) Ladybug

Appearance: Adult ladybird beetles are characterized by a dome-shaped back which sport a pair of wing covers which are usually red or orange in color and dotted with distinct black spots.

The larvae are considerably longer and thinner than their adult counterparts, and, are colorfully said to possess a “crocodile” like appearance. The larvae are usually black or brown in color.

Encouragement: Ladybird beetles are beneficial insects, and thus, under most normal circumstances, their populations should be encouraged as opposed to being decimated. They are beneficial in the sense that they prey upon aphids, with a typical specimen feeding over some two to three-hundred aphids over its’ lifetime.

Ladybird beetles may be encouraged through allowing weeds such as thistles and milkweed to establish themselves on the periphery of arable land.

Lifecycle: Ladybird beetles produce larvae which go through four instars (periods between molts before pupating and metamorphosing (transforming) to adults. Both the adults and larvae feed on aphids.

Simple Ladybird Beetle Lifecycle diagram

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Source of information for lifecycle diagram: http://www.ladybird-survey.org/lifecycle.aspx Accessed January 3rd 2014

(Source of information: Hans Dobson et al, Integrated Vegetable Pest Management – Safe and sustainable protection of small-scale brassicas and tomatoes:- A handbook for extension staff and trainers in Zimbabwe; 2002, Plant Protection Research Institute; Harare, Zimbabwe; page 26; as well as an article titled Ladybugs [of Florida] http://entnemdept.ufl.edu/creatures/beneficial/lady_beetles.htm accessed February 3rd 2014)

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Insect number seven: Leaf hopper Scientific name: (Cicadellidae family) Homalodisca vitripennis Type: Sap-sucking pest.

Hosts:

1) Cotton 2) Cowpeas 3) Eggplant 4) Other plants

Order: Hemiptera Common names:

1) Sharpshooters 2) Leafhoppers

Appearance: Possesses powerful hind-legs, enabling them tp quickly evade predation. They also characteristically slip behind leaves and stems when alarmed. Adults possess two pairs of wings and can be brown, green or yellow in color.

Damage: Leaf-hoppers are sap-sucking pests which attach themselves to the underside of the leaves of host plants from which and where they suck the sap which they covet. Their sap-sucking feeding habits cause leaf withering and subsequent loss of plant vigor due to reduced photosynthetic tissue and area.

Lifecycle: Adults usually over-winter in non-cultivated areas at the periphery of gardens.

When eggs are laid (usually in the stems and leaves of host plants), they hatch after a period of one to one and a half weeks. The nymphs molt five times en route to adulthood.

Simple Leafhopper Lifecycle Diagram

Source of information: http://www.hindawi.com/journals/psyche/2012/930975.fig.003.jpg Accessed February 3rd 2014

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Control: 



Encouraging parasitic wasps to help predate the pests can be done through (for instance) allowing the growth/cultivation of dill and/or fennel. Alternatively, one may allow some milkweed and thistles to grow so as to attract the wasps.

Thorough removal of crop residues helps to reduce over-wintering sights of the pest.

(Source of information:Vukasin et al’s Production without Destruction1995 Natural Farming Network Zimbabwe, Harare, Zimbabwe, page 93; as well as an article titled Sharpshooters http://entnemdept.ufl.edu/creatures/fruit/sharpshooters/sharpshooters.htm Accessed February 3rd 2014)

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Insect number eight: Locust Scientific and common names: 1) Nomadacris septemfasciata (the red locust) 2) Locusta migratoria migratoides (migratory locust) Hosts:

1) Maize 2) Sorghum 3) Indigenous grasses 4) Other plants…

Order: Orthoptera Appearance: Adult migratory locusts can span and vary in length from one and a half to two inches, and, are usually pale yellow in color.

The red locust can be almost three inches in length, and usually has a red tinge in color which is more easily observable when migrating in swarms.

Damage: Damage is usually foliar, ranging from negligible to complete defoliation depending on whether the specimens are still at the hopper or locust stage, as well as pest population densities.

Lifecycle: Female migratory locust specimens lay eggs in the soil in batches which are also known as “pods”. A single female can lay/deposit between fifty to two hundred eggs which are usually split into five batches/pods.

Once laid, the eggs can hatch after a period of as early as one and half to three weeks later, or, as long and as late as a year. The key/determining factor with regards to this is that of environmental conditions, where speedy hatching occurs in warm and moist conditions, whilst very dry conditions retard egg hatching.

After the eggs have hatched, nymphs emerge, and these go through an incomplete metamorphosis of five molts en-route to becoming adults.

It is the adults which are the most harmful stage of this insect pests’ lifecycle, as, depending on numbers and available food, they can consume up to their own weight in food each day, with an adult locusts’ lifespan in such favorable conditions being slightly longer than a month.

Simple Locust Lifecycle Diagram

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Source of lifecycle picture: http://www.soilcropandmore.info/crops/CottonInformation/insect/B933/ctn057.jpg accessed January 30th 2014

Control: Locusts are particularly difficult to control because of their migratory nature as well as large swarms. The most convenient and least costly stage at which to control them is at the grasshopper stage. The generally accepted economic injury level/threshold (that is, insect pest population density which will render economic damage) is that of five hoppers per square meter, upon which expert assistance (usually from agricultural extension offices) must be sought, and sought with dispatch.

Usually, Fenitrothion is the insecticide of choice which is sprayed ahead of the infestation’s direction of travel in and through the crop stand.

In the event that the infestation is caused by adult locusts, great co-ordination is needed by nations which will need to commit vast sums and resources to both track the movements of, and spray (usually aerially) the marauding swarm of locusts.

(Sources of information: article by Diana E. Taylor, titled Grasshoppers; http://www.pestsandcrops.com/index_files/Page811.htm ; accessed December 30th 2013; as well as an article titled Eastern lubber grasshopper http://entnemdept.ufl.edu/creatures/orn/lubber.htm ; accessed December 30th 2013)

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Insect number nine: Maize stalkborer Scientific name: Busseola fusca

Hosts:

1) Maize 2) Sorghum 3) Cotton 4) Sugarcane 5) Tomato

Order: Lepidoptera

Damage: Busseola fusca is almost, hands-down, the key insect pest encountered in maize production, and it leaves much damage and destruction in its wake. In maize plants:  Window-pane like effects (that is, gaping holes) are observed on leaves emerging from the funnels of infested plants (usually on young maize plants which are between twelve to forty inches in height.  Frass, or insect droppings are usually found on the maize plant’s cobs and stems.  Older/mature maize plants are usually riddled with white caterpillars tunneling in the stems, and frass protruding from the base of the stem.  In severe and prolonged infestations, one will find dry tassels, as well as tassels beginning to break off, and, at times, increased incidences of lodging of the maize plants.  Young maize plants usually become stunted after an infestation.  Maize cobs are ruined through the larvae having fed on the maize kernels, or, as a result of the frass having provided a conducive breeding ground of harmful fungi which cause severe discoloration and loss of market value of the maize.

Lifecycle: A single female specimen of the mature adult moth lays up to four score (eighty) eggs between the base of a leaf sheath and stem of the host plant. Upon hatching (usually a week later), the larvae climb into the funnel of the plant and feed for one, to one and a half weeks.

After this, they either bore into the stem of the host plant and feed, or, move on to another host plant and bore into and feed into the stem of that new host plant. Either way, and in any case, they subsequently feed and bore in the stem for some thirty to forty days, leaving trails of frass in their boring tunnels. After six instars which all occur over the course of those thirty to forty days of larval development, the larvae pupate. Depending on temperatures (usually, the warmer the quicker), after some three weeks, adult moths emerge, ready to recapitulate the lifecycle of this destructive insect pest.

Simple Lifecycle Diagram

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Source of lifecycle picture: http://www.push-pull.net/images/Busseola%20fusca.jpg Accessed February 3rd 2014

Control:  In the Zimbabwean Highveld (areas 1200 meters above datum/sea level) encouraging the presence of parasitic wasps has been known to reduce infestations from this pest.  In instances where more than ten percent of one’s maize crop stand has been infested with Busseola fusca, one may apply granular contact insecticides down the funnel of the plants (this is usually done some four weeks after plant/crop emergence). A follow up application may be done one and a half to two weeks later in the case of severe Page | 67

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





infestation. Examples of granular contact insecticides to apply include 1% granular endosulfan, as well as 2,5% granular dipterex, with both being applied at a rate of three to four kilograms per hectare.

Deep ploughing or burning off of stover may be done so as to smother or burn the larvae. The former method may destroy soil structure over time, whist the latter method usually causes massive air pollution through the release of vast amounts of carbon dioxide and other greenhouse gases.

If one is practicing reduced or conservation tillage, they must just make sure that all standing maize stalks remaining after harvesting must be knocked down and cracked open so as desiccate over-wintering and pupating larvae.

In nations which allow it, one may consider planting maize varieties which are less susceptible to Busseola fusca infestation. For instance, one may plant varieties which make use of the Bacillus thuringiensis (Bt) gene.

(Sources of information: Diana E. Taylor’s article Maize stalk borer http://www.pestsandcrops.com/index_files/Page2615.htm ; accessed December 30th 2013 ; as well as the lecture notes of Mr. Shadreck Hunduza of Blackfordby College of Agriculture, Concession area, Zimbabwe)

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Insect number ten: Red bollworm Scientific name: Hosts:

Diparopsis castanea

Cotton

Order: Lepidoptera Appearance: Red bollworm can vary between an inch to nearly an inch and a half in length (some twenty-five to thirty-five millimeters); they also usually sport red markings near their back.

Red bollworm moths are stout-bodied with a maximum wingspan of some thirty-five millimeters. The hind-wings and body are cream-colored, whilst the forewings are usually reddish brown in the section nearest the moth’s body.

Damage: The bulk of the damage is inflicted by the larvae feeding on the bolls (pods or capsules) of the cotton plant. If there is an infestation on cotton plants which have not yet developed bolls, the larvae can also just as well feed on the growing points of the plants. The effect of such an action is mainly that of disfigured plants, resulting in curtailed efficiency of machine harvesting operation, though hand harvesting is still an available alternative in less severe cases.

Lifecycle: Soon after emergence, adult moths mate, and, in a typical female specimen’s lifetime, up to three hundred eggs may be laid. The eggs (which are typically bluish and spiny) are normally laid near plant buds and growing points.

The laid eggs hatch nearly five days after having being laid, and undergo five instars before pupation. These larval developments can vary in length/duration of time, from two weeks to well over a month. The duration of this development largely depends on temperatures, with lower temperatures tending to retard/ slow down larval development.

When pupation is imminent, the larvae burrow some three inches below the soil surface, and, after a few weeks, most pupae emerge as adult moths. Some pupae however, enter diapauses (an enforced dormancy of sorts) with them emerging in the following spring or cotton growing season to infest new cotton crop stands.

Simple Red Bollworm Lifecycle Diagram

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Source of lifecycle diagram: http://www.soilcropandmore.info/crops/CottonInformation/insect/B933/ctn012.jpg accessed February 1st 2014.

Control: As one authority attests in terms of cotton production in the nation of Zimbabwe: “The main method of control of this pest in cotton, along with pink bollworm and other pests is the legislated growing season of the crop. This allows cotton to be planted only from a specified date, and requires the harvested crop to be completely destroyed by a further specified date at the end of the season. The careful observation of this growing period has for many years kept pests of this nature within reasonable bounds, and in fact has practically kept pink bollworms away as a pest altogether.�(Source of information: Diana E. Taylor in an article titled Red bollworm http://www.pestsandcrops.com/index_files/Page1906.htm accessed December 30th 2013) (Source of information: Diana E. Taylor in an article titled Red bollworm http://www.pestsandcrops.com/index_files/Page1906.htm accessed December 30th 2013)

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Insect number eleven: Semi looper Scientific name:

Thysanoplusia orichalcea

Hosts: 1) Key insect pest of Soya-beans in Southern Africa.

2) Cabbage.

Order: Lepidoptera Common names: 1) Cabbage looper.

2) Semi looper.

Appearance: Semi-looper caterpillars are the larval stages of the Thysanoplusia orichalcea moths. The adult moths themselves sport brownish colored forewings with the hindwings sporting a paler hue of the same color.

The semi-looper caterpillars themselves are usually a bright and somewhat pale-green color. The key identifying characteristic concerning this insect pest, is that it sports three pairs of legs which are all situated in the upper quadrant or third of the caterpillar’s body.

This creates a situation such that, as the insect moves –or has moved rather- its’ forelegs, the rest of its’ body follows along by having to arch and fold/loop like an accordion, forming a half or semi-loop shape of sorts, hence the caterpillar’s fitting and colorful moniker of being called a semi-looper.

Damage: The entire leaf surfaces of the host plant are consumed, with only the veins being usually left. In severe infestations on soya-bean crop stands, young developing pods may also be consumed by this insect pest.

Lifecycle: Female adult specimens of the Thysanoplusia orichalcea moth, lay pale green eggs on the underside of the leaves, or, directly on the stem of young plants. The eggs hatch after some three or four days from which first instar larvae emerge. The larvae undergo five or six instars, growing (on average) five to six millimeters in length per instar, such that, by the time of the final instar, they are nearly four centimeters (one and a half inches) in length.

The appetite of the semi-looper caterpillar tends to be more voracious as it goes through the instars.

Pupation occurs shortly after the final instar, and the site of pupation is usually the underside of the plant’s leaf, where one will find a whitish silky cocoon which characteristically wiggles when disturbed.

The entire lifecycle of this insect pest is, on average, a month long (normally ranging from between twenty-three to thirty-five days).

Simple Semi-looper Lifecycle Diagram

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Source of lifecycle diagram: http://www.knowledgebank.irri.org/RiceDoctor/images/stories/image3.gif accessed February 3rd 2014

Control:   

Carbaryl has been known to be effective , but can be phytotoxic to the soyabean crop.

Parasitic wasps may also be encouraged to proliferate so as to aid in the fight against this insect pest.

A providential act of nature which also has a most devastating effect on the semilooper caterpillar infestations is that of the nuclear polyhedrosis virus (NPV). In rainy and overcast weather conditions, the virus tends to thrive, whilst hot and dry weather conditions tend to discourage its’ development. In some areas f the Highveld of Zimbabwe (areas of that southern African nation which are above 1200 meters above datum level), some farmers do not have to take any action against the semi-looper caterpillars as the virus will more often than not, manifest and decimate them.

Farmers themselves are encouraged to identify diseased/sickly semi-looper caterpillars (which are usually yellowish in color) preserve them by freezing, and then introduce them the next growing season when a semi-looper caterpillar outbreak/infestation occurs. The stored caterpillar is squashed/crushed, and, its’

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diseased fluids will be spread by rain drop splashes on to other plants and subsequently, the caterpillars themselves.

The NPV virus causes these caterpillars to turn a sickly yellow in color, and then brown; eventually, they burst, with their diseased fluids spreading onto other plant parts and being splashed onto others through rain drop splashes.

(Source of information: An article on semi-looper caterpillars by Diana E. Taylor http://www.pestsandcrops.com/index_files/Page3663.htm ; accessed December 30th, 2013; as well as an article titled Cabbage looper entnemdept.ufl.edu/creatures/veg/leaf/cabbage_looper.htm ; accessed January 7th 2014)

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Insect number twelve: Spider-mites Species name:

Tetranychus spp.

Type: Chewing pest (nymphs and adults).

Hosts: 1) Tomatoes 2) Beans 3) Cucumber 4) Peppers 5) Cotton 6) Tobacco 7) Maize 8) Sorghum 9) Eggplant.

Order: Arachnida (spider-mites are technically not insects).

Common names:

Red spider-mite; spider-mites.

Appearance: Adult spider mites are usually red-colored arachnids which are roughly a quarter millimeter in length; and, true to arachnid proclivity, sport four pairs of legs and possess a large abdomen. Spider-mites characteristically tend to leave fine silk webbing on the leaves of host plants, which protect them from predators and excess moisture.

Damage: This chewing pest causes browning/bronzing and eventual falling of leaves from affected plants. In tomatoes in particular, fruit quality is affected to unmarketable status in cases of severe infestation. This will be due to severe mottling (spots and blotching) of the affected tomato plants.

Lifecycle: Eggs are round/ovoid and laid on the underside of leaves. The result is the hatching of six-legged larvae, which, then become eight-legged nymphs, and subsequent fullgrown adults which are usually a quarter millimeter in length.

Spider-mites tend to favor windy, dry conditions, as, it is such under such conditions that they are able to proliferate and break-out.

Simple Red-spider mite Lifecycle Diagram

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Source of spider mite lifecycle diagram: https://insects.tamu.edu/students/undergrad/ento402/Cotton_files/Cotton_popup/spider_mite_life.jp g accessed February 3rd 2014.

Control: 

 



Inter-planting with onion, garlic as well as possibly mulching with strong-smelling plants (such as Mexican marigold) tends to have a repulsive effect on red-spider mites.

Resistant varieties of crops –such as the Rossol variety of tomato- is another pragmatic measure of controlling red-spider mite infestations.

The presence and proliferation of natural predators, such as, for instance, predatory mites, is another workable method of control. One host plant of beneficial predatory mites is that of perennial pigeon pea.

Good field hygiene practices, such as, for instance, cleaning tomato stacking materials before use in the next season, are of invaluable import. Another instance of good field hygiene practice is to consciously perform key operations such as weeding and spraying in a manner in which one moves from areas of lower red-spider mite infestation, to areas of higher red-spider mite infestation.

((Sources of information: Hans Dobson et al, Integrated Vegetable Pest Management – Safe and sustainable protection of small-scale brassicas and tomatoes:- A handbook for extension staff and trainers in Zimbabwe; 2002, Plant Protection Research Institute; Harare, Zimbabwe; pages 104-106; as well as Vukasin et al’s Production without Destruction 1995 Natural Farming Network Zimbabwe, Harare, Zimbabwe; pages 81-82)

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Insect number thirteen: Stink bugs Scientific name: Chinavia halaris Hosts: 1) Soya beans 2) Garden beans 3) Tomatoes 4) Wheat 5) Macadamia nuts 6) Many others.

Order: Hemiptera Appearance: Widely recognized by many, this insect pest is part of the shield bug family, and, is characteristically green in color.

Damage: Stink bugs are cosmopolitan insects with a broad host range/spectrum, and particularly enjoy consuming developing fruit. The proboscis of this insect pest has a piercing action which causes local necrosis and can result in leaf spotting and deformation, resulting in loss of market value. In severe cases where damage on fruit is inflicted early, the fruit is shed, resulting in complete loss/spoilage. In tobacco plants, stink bugs do at times feed on new leaves with the shoots, resulting in wilting.

Lifecycle: Eggs are laid on the underside of leaves, and after hatching, the nymphs undergo an incomplete metamorphosis to adult stage which consists of five instars over a period of eight weeks.

Simple Stink bug Lifecycle Diagram

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Source of infographic : http://ww1.prweb.com/prfiles/2014/02/04/11549821/Infographic%20StinkBugLifeCycle.jpg Accessed February 5th 2014

Control: 

Contact insecticides such as Monocrotophos and of endosulfan should be of good efficacy.

(Source of information: article on stink bug by Diana E. Taylor http://www.pestsandcrops.com/index_files/Page1050.htm

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; accessed December 30th 2013 ; as well as an article titled Green Stink bug http://entnemdept.ufl.edu/creatures/veg/bean/green_stink_bug.htm Accessed February 5th 2014 )

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Insect number fourteen: Thrips Species name(s):

1) Thrips spp.

2) Frankliniella spp.

Type: Sucking pest (nymphs and adult) Hosts:

1) Brassicas 2) Tomatoes 3) Onions 4) Cucurbits 5) Peppers 6) Cotton and others

Order: Thysanoptera Common names:

A) Onion thrips.

B) Potato thrips.

C) Western flower thrips.

Appearance: Thrips are very small and barely visible to the naked human eye. Adult thrips are nearly two millimeters in length, and, are usually black, brown or yellowish orange. The larvae are greenish in color and tend to look like maggots.

Damage: Adults and nymphs weaken the plant and cause silvery colored leaves through piercing leaf surfaces from which to suck sap from. Such action causes loss to the plant vigor and yield.

Thrips also tend to engage in the unsanitary habit of excreting frass on the leaf surface, thereby furnishing a salubrious environment for harmful fungi to grow.

To add injury to insult, thrips are infamous vectors of certain crop viruses; passing viruses from infected plants to non-infected specimens. An example of a virus which they are a vector of is that of tomato spotted wilt, which, as the name plainly and clearly denotes, affects tomatoes. This virus mainly causes severe yellowing and stunting of the tomato fruit.

Lifecycle: Adults make cuts/incisions on a plant surface and lay eggs in the opening. Within a few days, larvae emerge (which, usually, are similar in appearance to green maggots).

After feeding, the larvae drop to the soil to pupate and emerge as mature adults. At this stage, they crawl or fly back into the host plant so as to feed and mate/reproduce. Damage is thus inflicted at both the larval and adult stages.

Simple Thrips Lifecycle Diagram

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Source of information on thrip lifecycle: https://cisr.ucr.edu/images/thrips_lifecycle_small.jpg Accessed February 3rd 2014

Control:   





Inter-cropping with repellent, strong-smelling crops such as onion and garlic is known to mitigate thrip infestations.

Yellow sticky traps at the periphery of garden beds are known to lower thrip numbers through frustrating their reproductive cycle.

Heavy mulching with good quality mulch aids in preventing the insect pests’ larvae from reaching the soil in order to pupate. The mulch’s efficacy may be compounded and further expedited through the use of repellent plants such as Tagetes minuta (Mexican marigold), Bidens pilosa (Black jack) and other marigold plants.

Encouragement of natural predators such as predatory mites and spiders is also known to work. Perennial pigeon pea and refraining from the use of broad spectrum pesticides will aid in building up numbers of these natural predators of thrips.

Thorough cultivation and seedbed preparation can help destroy pupae already resident in the soil before growing of the next crop.

(Source of information: Hans Dobson et al, Integrated Vegetable Pest Management – Safe and sustainable protection of small-scale brassicas and tomatoes:- A handbook for extension staff and trainers in Zimbabwe; 2002, Plant Protection Research Institute; Harare, Zimbabwe; pages 75-76)

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Insect number fifteen: Parasitoid Wasp Scientific name: Copidosoma spp.

Type: Usually beneficial as it parasitizes many insect pests (such as aphids and leaf miners) Host(s): Aphids, leaf miners and others.

Order: Hymenoptera

Appearance: Adult specimens are black in color and range in being one-hundredth to three quarters of an inch long, making them almost imperceptible at most times when one is not scouting, concentrating on or closely observing things. Female adult specimens characteristically possess a long and pronounced ovipositor (egg-laying structure). Both adult specimens also possess long, thread (fili-form) antennae.

Lifecycle: After mating, female specimens seek a suitable host (such as an aphid, leaf miner, or flies) into which to lay an egg. The egg laid in the host hatches, and the larva (or larvae in the case of some strains of wasp) slowly but surely feed on the host. In the case of an aphid, the parasitized aphid is called an aphid mummy, because, when the larvae pupate inside them, they become hard and brownish in color, and eventually die.

Simple Parasitoid Wasp lifecycle Diagram

Source of information concerning parasitoid wasp lifecycle: http://academic.reed.edu/biology/professors/srenn/pages/teaching/web_2010/bpls_sitefinal/images/parasitelifecycle.gif accessed February 3rd 2014 Page | 81

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Encouragement: Since most parasitoid wasps are beneficial insects, their numbers should usually be encouraged to proliferate. This can be done through:  

Allowing or cultivating the growth of plants with delicate flowers which help to shelter them. Examples include dill and fennel.

A few milkweed and thistle plants may also be allowed to grow on non-cultivated parts of land to encourage their numbers, as such plants encourage the establishment of non-pest species of aphid, which they will subsequently feed on.

(Sources of information: Hans Dobson et al, Integrated Vegetable Pest Management – Safe and sustainable protection of small-scale brassicas and tomatoes:- A handbook for extension staff and trainers in Zimbabwe; 2002, Plant Protection Research Institute; Harare, Zimbabwe; pages 26 and 27; as well as Vukasin et al’s Production Without Destruction; page 93; and, an article titled Parasitic Wasp from https://insects.tamu.edu/fieldguide/cimg329.html Accessed February 4th 2014)

Page | 82

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Blackfordby College of Agriculture Weeds and Insects project; General Diploma in Agriculture partial fulfilment requirement. Project submitted on March 3rd, Roman year 2014 C.E.

Key to Specimens supplied with/alongside this Insects project: 1) = Aphid.

2) = Budworm.

3) = Cotton stainer.

4) = Cutworm.

5) = Diamondback moth.

6) = Ladybird beetle.

7) = Leaf hopper.

8) = Locust.

9) = Maize stalkborer.

10) = Red bollworm.

11) = Semi-looper.

12) = Spider mites.

13) = Stink bug.

14) = Thrip.

15) = Wasp.

16) = Assassin bug.

17) = False wire worm.

18) = Snout beetle.

19) = Whitefly.

20) = Whitegrub.

Page | 83

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