Weed identification presentation 2011

INTERGRATED WEED IDENTIFICATION & MANAGEMENT COURSE 2011 Ministry of Agriculture Mechanization and Irrigation Development: Department of Research and Specialist Services(DR&SS) Agronomy Research Institute, Weed Research Team , P/Bag 2004 Mazowe

MANDATE OF WEED RESEARCH TEAM • To evaluate herbicides for registration purposes which are eventually used by farmers in Zimbabwe • To solve weed problems with special emphasis in agriculture • Carry out weed inspections in export seed production fields in Zimbabwe.

• Conduct weed identification and management course

IMPORTANT BROADLEAVED WEEDS IN SELECTED FIELD CROPS IN ZIMBABWE

Ipomoea plebia (Sabi morning glory,

Characteristics -trailing habit, makes it a problem in harvesting crops like maize, soya, sunflower etc.

-heart shaped leaves.

-small, whitish flowers.

Ipomoea plebia (Sabi morning glory, Katewe

-V- shaped cotyledons -heart shaped true leaves

Bidens pilosa (Black jack, Tsine, Mhuwu, Umhlabangubo) -inflorescence with flowers with a yellow disc and white ray florets.

-Seed is black and not shiny, with 2-3 barbs that are 7-13mm long which enable it to cling to clothes.

-Stem is four sided and deep purple in colour almost black, hence the name black jack.

Bidens pilosa (Black jack, Tsine, Mhuwu, Umhlabangubo) Characteristics -dark purple coloured stem -cotyledons are elongated and smooth margined -true leaves slightly feathery

Tagetes minuta L. (Mexican marigold, Khaki bos weed, Jeremani, Kambanje, Imbanje yonxiwa) Characteristics -yellow inflorescence with black seeds which are more shiny when viewed at an angle to the sun.

-stem and branches are pale brownish and sometimes reddish in colour.

Tagetes minuta L. (Mexican marigold, Khaki bos weed, Jeremani, Kambanje, Imbanje yonxiwa) SEEDLING STAGE Characteristics -resembles the black jack, but leaves are lighter green in colour .

-cotyledons are shorter -leaves have a distinct khaki boss smell when rubbed between fingers.

COMPARISON Bidens pilosa and Tagetes minuta B.pilosa – cotyledons more longer and pointed; deeper green colour; dark purple almost black stem; less feathery appearance of the true leaves.

T.minuta – cotyledons shorter and less pointed; pale green color; true leaves with a much more feathery appearance.

Schkuhria pinnata (Lam.) Dwarf marigold, Rukarwa FLOWERING STAGE Characteristics -Pin shaped leaves -bright yellow flowers -much branched, dwarf plant.

Schkuhria pinnata (Lam.) Dwarf marigold, Rukarwa Seedling and stage -easily identified by the finned (pin shaped) leaves , hence the botanical name pinnata and cotyledons are clipped at the tips.

-stem and leaves have a light green colour.

Cleome monophylla L. Spindle pod, Mujakari, Ulude -Stem usually green, inflorescence is rose to pink coloured.

-Fruits are elongated spindle shaped pods which are green.

Cleome monophylla L. Spindle pod, Mujakari, Ulude SEEDLING STAGE Characteristics -shorter, more rounded cotyledons, more shorter than the true leaves.

-Purplish colour underneath the cotyledons and leaves.

Datura stramonium Stink blaar, Chowa, Gagu

Broad jagged leaves.

-Trumpet shaped flower -Fruit is spiked, purplish stem -Fruit splits into 4 valves at the tip.

-Purplish dark stem

Datura stramonium L. Stink blaar, Chowa, Gagu SEEDLING STAGE Characteristics -elongated cotyledons.

-cotyledons and leaves produce a distinct smell when rubbed between your fingers

Comparison Datura stramonium and Cleome monophylla Datura staramonium Cotyledons are long narrow and pointed. Squeeze leaves between fingers, they produce a pungent smell Cleome monophylla Cotyledons are shorter and rounded at the tip

Physalis angulata, Wild gooseberry, Muguziberi, Maguzubeli

Flower is yellow with 5 lobes.

-True leaves have distinct veins.

-Rounded inflated fruits look like Chinese lantern.

Physalis angulata, Wild gooseberry, Muguziberi, Maguzubeli

-Cotyledons are opposite each other at an angle hence the name angulata - the cotyledons are shaped like a builders trowel

Nicandra physalodes Apple of Peru, Gumachembere, The leaf has disinct veins which gives a wrinkled appearance.

-Flowers are purple - fruit has 5 distinct wings and less inflated than the fruits of P angulata.

Nicandra physalodes Apple of Peru, Gumachembere - The cotyledons are opposite each other in a straight line

Comparison -Nicandra physalodes.

-The cotyledons are opposite each other in a straight line -Physalis angulata -Cotyledons are opposite each other at an angle hence the name angulata - the cotyledons are shaped like a builders trowel.

Galinsoga parviflora Gallant soldier, Chaarendo A nuisance in gardens, and winter crops heavy soils and prone to water logging.

-True leaves look like spades of a playing card -Tiny yellow flowers

Galinsoga parviflora, Gallant soldier Seedling stage -In ward dent or notch - longer petioles

Leucas martinicensis, Bobbin weed, Nyamatumwa, Imbuya yamadhongi

Stem is 4 angled -Flowers are white - seed heads are bobbin shaped

Leucas martinicensis, Bobbin weed, Nyamatumwa, Imbuya yamadhongi

-Short leaf petioles cotyledons are closer to each other.

- true leaves wrinkled.

Ageratum conyzoides.

Billy goat weed, Kabarikire, Nyani -A hairy plant - Has small blue flowers.

- Wrinkled leaves

Ageratum conyzoides, Billy goat weed, Kabarikire, Nyani - Round cotyledons - Hairy plant

Comparison:G.parviflora, L.martinicensis, A.conyzoides

Richardia scabra Mexican clover.

Chinzungu, Isizambani

-Distinct groove which divides the leaf into 2 - Leaf is hair less - small white flowers -An indicator of low soil pH (acidity in soils)

Richardia scabra

Mexican clover.

Chinzungu, Isizambani

-Distinct groove which divides the leaf into 2 - Leaf is hair less

Acanthospermum hispidum, Chidhongi, Chaguduma, Ubhima

-The third most troublesome weed in Zimbabwe -An erect plant - has a spiked fruit - Small and yellow flowers

Acanthospermum hispidum, Chidhongi, Chaguduma, Ubhima

Round cotyledons Shiny hair less cotyledons and the true leaves have small hairs.

Conyza albida Fleabane, gonzo -Stem is woody - flower heads are white and fluffy - Rossette shape

Conyza albida Fleabane, gonzo Rossette shape - Resemble tobacco seedlings

Comparison -Conyza albida -Richardia scabra -Acanthospermum hispidum

Oxalis latifolia Purple garden sorrel, salt weed , Chimunyu, Umungumungwana Three butterfly shaped leaves - Has no stem

Oxalis latifolia Purple garden sorrel, salt weed , Chimunyu, Umungumungwana

Three butterfly shaped leaves supported by long petioles - Has no stem

Hibiscus meeusei Stock rose, sosoori, uGangampunza

Stem is woody with pricky hairs -Flower is bright yellow with a purplish centre.

- the leaf has 3 lobes

Hibiscus meeusei Stock rose, sosoori, uGangampunza

the true leaves has 3 lobes -Round cotyledons -The plant keeps those very round cotyledons through out its life

Chenopodium album, Fat hen, Lambsquarters, Kasunika The shiny white hairs on top of the leaves gives a frosted or crystalline appearance.

Seeds borne in clusters, with no petals.

A true aggressive winter weed.

Chenopodium album, Fat hen, Lambsquarters, Kasunika The shiny white hairs on top of the leaves gives a frosted or crystalline appearance.

Amaranthus hybridus Pigweed Bonongwe, Imbuya.

-Wine red seed heads -Distinct veins underneath the leaves

Amaranthus hybridus Pigweed Bonongwe, Imbuya.

Wine red stem.

Portulaca oleracea Purslane, Chifandichimuka

-A spreading appearance, fleshy red stem - Egg shaped fleshy leaves which are narrower towards the point of attachment -Small yellow flowers

Portulaca oleracea Purslane, Chifandichimuka - A spreading appearance - Egg shaped succulent leaves which are narrower towards the point of attachment

Comparison Chenopodium album Portulaca oleracea Amaranthus hybridus

IMPORTANT SEDGES IN SELECTED FIELD CROPS IN ZIMBABWE

Cyperus rotundus, Purple nutsedge, Purple nut grass, Ndave -The leaves spread at ground level -flower head is purple - underground has horizontally spreading rhizomes coated with dark coloured fibers.

Cyperus rotundus, Purple nutsedge, Purple nut grass, Ndave

The leaves spread at ground level and are deep green in colour

Cyperus esculentus, Yellow nutsedge, Water grass, Pfende

Stem is 3 angled - Leaves spread above the ground

comparison

Commelina benghalensis Wandering jew, Goche, Idabane A spreading and branching plant with long internodes. The flowers are blue-Can produce viable seeds both aerially and subterraneally.

- Has broad grass leaves with parallel veins.

Commelina benghalensis Wandering jew, Goche, Idabane

It emerges with a single funnel shaped leaf

IMPORTANT GRASS WEEDS IN SELECTED FIELD CROPS IN ZIMBABWE

Urochloa panicoides Garden urochloa, Mhande, Dlanyati

-Leaves are fairly elevated above the ground.

- pale green in colour - Rooting from lower nodes

Urochloa panicoides Garden urochloa, Mhande, Dlanyati -Leaves are fairly elevated above the ground.

-Longer and less broader leaf.

Panicum novermnerve Panicum, Barahanga, Hoka, Uhatsi -Dark green in colour -Leaves closer to the ground

Panicum novermnerve Panicum, Barahanga, Hoka, Uhatsi -Leaves closer to the ground -Much broader and less elongated, poited leaf

Comparison: U.panicoides, Panicum novermnerve

Rottboellia cochinchinensis Shamva grass, Itchy grass, Guinea fowl grass, Vave, Handifeni.

Second most troublesome weed in Zimbabwe.

-Common in Mazowe valley, Shamva area and Midlands - Has a dark red base.

-Cylindrical flowers consisting of individual ball and socket joint seeds, which breaks at maturity - Has minute stiff hairs on the upper surface of the leaf

Rottboellia conchinchinensis Shamva grass, Itchy grass, Guinea fowl grass, Vave, Handifeni.

Makes a spiky sort of appearance when emerging

Eleusine indica Rapoko grass, Sawi, samombe, Umunyankomo -the most common and aggressive weed in Zimbabwe - flat dark green colour - pronounced mid rib

Eleusine indica Rapoko grass, Sawi, samombe, Umunyankomo Shows a rather sudden sideways branching of the leaves - Whitish base

Setaria verticillata Burgrass, Bristly foxtail, Nama, Chinonama Green to purplish spikelets - Barbs tend to cling to human clothes or animal hair

Setaria verticillata Burgrass, Bristly foxtail, Nama, Chinonama -Shows a gradual sideways branching of the leaves - lighter green in colour

Setaria pumila Annual timothy, thinner grass, Horse grass, Chiraramhene Seed heads and nodes are red in colour.

- The stem is cylindrical in shape at seedling stage and at a later stage becomes flat.

Setaria pumila Annual timothy, thinner grass, Horse grass, Chiraramhene

Thin grass cylindrical in shape at seedling stage.

Melinis repens Natal red top, fairy grass, Bhurakwacha Reddish fluffy seed heads which can easily be carried by wind.

-At all stages the leaves are at almost right angles to the stem.

Melinis repens Natal red top, fairy grass, Bhurakwacha -Purplish stem -leaves are at almost right angles to the stem.

Comparison:E.indica, S.verticillata, S.pumila, M.repens

Cynodon dactylon Couch grass, Quick grass, Bahama grass, Tsangadzi, Kapinga, Uqethu

- Serious problem in reduced tillage Perennial -Spreading and creeping by stolons and rhizomes - rooted at the nodes

Cynodon dactylon Couch grass, Quick grass, Bahama grass, Tsangadzi, Kapinga, Uqethu

Long narrow leaves

Emerging problematic weeds in selected field crops in Zimbabwe • Identified during weed inspections carried out by the Weed Research Team for the past 4 seasons

Avena fatua wild oats

-The leaves spiral in an anti-clock wise direction - can be confused with wheat - leaves are hairy -Noxious weed in Zimbabwe

Dactyloctenium aegyptium Crow’s foot, Bwerere, Imhunga -flat stem -Spikes are not pointed - Rooting at nodes

Cochorus tridens Wild jute, derere, Nyenje, Idelele

-Stem is woody - yellow flowers - leaves long and serrated

Acalypha crenata Acalypha, Kariringwe, Kahwahwa

Rounded cotyledons -Hairy stem and petioles -Cluster of green to yellow flowers

Vernonia poskeana Vernonia Kavanzi, Mzangilani, Inyathelo

Purple flowers - Reddish stem

Sida alba Spiny sida, Chimutsvairo

When small similar to stock rose but the leaves are more pointed and later on serrated

Trichodesma zeylanicum Late weed, Goza, Nyarumundu

-Erect and scattered harsh hairs on stem and leaves.

- Blue flowers with white eye -Emerges late in the season approximately 8 weeks after the first effective rains

Gisekia africana Gisekia, Dungambizi, Tarambiya -Similar to purslane with green stems - narrow elongated and fleshy leaves with distinct midrib

Eurphobia heterophylla Wild pointesettia, Chimukaka

-elevated cotyledon - bottom of stem is reddish - green 3 lobed fruits

Ipomoea purpurea Morning glory, Katewe

Characteristics -V- shaped cotyledons -heart shaped true leaves -Twinning annual - Purple flowers with white centre

Convolvolus arvensis Field Bind weed Climbing perennial with very deep spreading roots.

-Roots give rise to numerous aerial shoots - stems twinning almost to 3 m long.

- fruits are brownish, two celled, splitting into 4 valves, four seeded

Solanum nigrum Black night shade,

-A variable annual or biennial herb up to 60 cm high reproducing from seeds.

-stem is cylindrical, erect, much-branched Inflorescence consists of 3-7 flowers.

-fruit is a round, fleshy berry up to 6mm in diameter black when ripe

Vernonia ambigua Iron weed

-Bushy annual herb up to 60 cm tall Stem is woody, ribbed, hairy and leafy especially at flowering time.

- Reproducing from seeds

Apium leptophyllum Wild celery

Much into numerous branched herb -stem green -Leaves alternate, base of petiole with membranous wings -very finely divided into numerous linear narrow lobes

Argemone mexicana Mexican Poppy, Mexican Thistle A much branched, prickly, annual herb with rosette shape -white flowers, with yellow stamens.

-the plant exudes a yellow juice when cut -blue green leaves that are sessile -veins of the leaves are outlined in greyish white on the upper surface

Oxalis corniculata Creeping sorrel -Creeping stoloniferous herbs with aerial stems -stems brown -leaves alternate, three– foliate winged below -small yellow flowers -reproduces through seed

Amaranthus spinosus thorny pigweed, spiny amaranth An erect, thorny, prickly annual herb up to 60 cm high.

-reproducing from seeds -stem is round, fleshy and hair less -greenish to reddish stem -Flowers occur in clusters.

-distinct thorns on the stem, makes it different from A.hybridus

Echinochloa colona Jungle rice

-annual grass -Roots sometimes at lower nodes - spikelets are crowded at rachis

Digitaria sanguinalis Crab finger grass

-Annual grass -Rooting at the lower nodes -Leaves often hairy

Important parasitic weeds in selected field crops in Zimbabwe • Striga asiatica • Alectra vogelli

Striga asiatica (Witch weed, Bise) A parasitic weed in cereals -forms root attachments with the host -characterized by bright red coloured flowers - 4 lobed corolla (petals) -stem green -linear shaped leaves

Alectra vogelli (Witch weed, Bise remunyemba) -parasitic weed in legumes which forms root attachments with the host.

-produces bright yellow flowers and reproduces through seed

Familiarization in the green house

Man in blue work suit for any assistance

Tripod stand

Thank you Tatenda Siyabonga