Biosecurity tips to prevent Yellow and Black Sigatoka

Biosecurity tips

to prevent yellow and black sigatoka

FREEDOM FROM THESE pests ensures that Australia’s banana growers benefit from lower production costs, especially when it comes to the management of pests, and production of a superior quality product.

Prevention is the most cost-effective strategy to protect banana farms and the banana industry from biosecurity threats. Improved awareness and farm biosecurity will increase the chance of early detection of banana pests if they are introduced into Australia.

Early detection and response can reduce the impact to your farm and the whole industry, and increase the likelihood of successful eradication.

The exotic disease Black Sigatoka (sometimes referred to as black leaf streak) is caused by the fungus Mycosphaerella fijiensis and is one of the most devastating leaf diseases of banana around the world.

It’s estimated that it can reduce banana yields by 50 per cent. Severely infected leaves die, significantly reducing fruit yield and causing mixed and premature ripening of bunches.

Leaf symptoms of Black Sigatoka are very similar to those produced by yellow sigatoka (which is present in Australia). In Black Sigatoka, early leaf streaks are reddish to rusty-brown, longer and broader than yellow sigatoka and most evident on the lower leaf surface.

In comparison, early streaks of yellow sigatoka are yellow-green, narrower and shorter, and more prominent on the upper leaf surface. Both pathogens can be present on the one plant. Laboratory testing is required to reliably distinguish these pests.

The threat of black sigatoka to the Australian banana growing industry is very real. There were several outbreaks of black sigatoka on the Cape York Peninsula during the 1980s and 90s.

The only outbreak in an Australian commercial production area occurred in Tully, north Queensland, in 2001 – the successful eradication of the disease was a world first. Reinstatement of mainland Australia’s pest free status for black sigatoka occurred in 2005.

For growers, the biosecurity measures used to prevent yellow sigatoka from entering and becoming established on your banana plantation also act to prevent an incursion of black sigatoka, considered a greater threat to the industry.

Yellow sigatoka is by far the major disease on the wet tropical coast as it is favoured by warm, moist conditions. Planting material is the most common method of spreading pests and diseases.

Control measures include a combination of optimal planting density, regular deleafing of diseased leaves, scheduled fungicide sprays and an integrated pest management approach. Using drippers or mini sprinklers for irrigation uses water efficiently and reduces yellow sigatoka infection.

Biosecurity is the responsibility of you and every person visiting or working on your farm. Plant Health Australia, the Australian Banana Growers’ Council (ABGC) and the Queensland Government have developed the Farm Biosecurity Manual for the Banana Industry to help reduce the risk of exotic and endemic pests becoming established in crops. The manual is designed to assist you in protecting your banana farm and your industry from invasive pests using simple, yet effective preventative strategies.

The manual includes pest fact sheets; tips on crop monitoring and limiting movement of people, vehicles and equipment near your plants; sources of planting and propagation material; farm hygiene; and the use of signs to indicate to visitors and workers the need for cleanliness while on your property. To encourage record keeping, a farm biosecurity checklist, visitor record sheet and pest monitoring record sheet are available from the manual.

Copies are available from www.phau. com.au/go/phau/biosecurity/banana

The Australian banana industry is at risk from many invasive pests which are present in overseas countries. From Plant Health Australia.

Black Sigatoka.

Frank Sciacca takes some preventative measures.

22 grower services

A ‘Stoller’ program for banana growers

An Australian company that specialises in liquid fertilisers and specialty nutrients is encouraging more banana growers to implement the use of their products.

WITH MORE THAN 40 years’ experience, Stoller Australia, which is part of the world wide Stoller Group, has an in-depth understanding of all nutrients and can help banana growers to develop programs that will help plants grow in in a variety of conditions.

Mr Shaw said he has been working with a number of banana growers over the last few years – and the results are definitely showing.

“We’ve been looking at improving vigour and establishment of newly planted trees, maintaining and increasing production during winter months, under skin chill and improving the general efficiency of the growers nutrition and fertiliser programs,” Mr Shaw said.

“We start by working with growers and distributors to help assess their nutrition programs, so that we make sure we get it right the first time,” he said.

“We are able to streamline a grower’s nutrition/fertiliser program and introduce Stoller’s unique, patented products such as Bio-forge, Set Enhanced, Rootfeed and others.

“These products each have their own special mode of action such as controlling and regulating the effects caused by weather stress events, as well as improving Calcium uptake and root growth stimulation,” Mr Shaw said.

Atherton Tablelands banana grower Frank Trimarchi has been using the Stoller range for more than 18 months.

After a few trials, Mr Trimarchi started using the Stoller range consistently, noting that the improved quality and yield of his fruit was definitely noticeable after only a few months. “Last winter was a particularly cold one, and using Stoller products ensured that we increased our production and quality of Lady Finger by more than 1000 bunches from the same acreage as the previous winter,” Mr Trimarchi said.

“We also achieved a similar result with Cavendish,” he said.

Mr Shaw went on to say that as an R&D focused company, Stoller invests more than $100 thousand a year towards looking at better ways of how they can assist growers.

“I encourage all banana growers to get in contact with us and allow us show you how we can do the same for your farm, as we did for Mr Trimarchi,” Mr Shaw said.

For more information, contact North Queensland Territory Manager, Martin Shaw on 0418 808 438 or via email at martin@stoller. com.au, or visit the Stoller website at www.stoller.com.au.

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By Glenn Cardwell, Accredited Practising Dietitian to Australian Bananas.

Taking the myth out of bananas

WHEN I WAS first asked if it was true that bananas were constipating I thought “Who dreamt that one up?” When I heard it a few more times I realised that it was an ingrained myth. Sadly, ingrained myths are very hard to budge. Even sadder, nobody even asks whether the story is true or not.

Let’s be blunt. Bananas have fibre and fibre helps keep you regular which is a polite way of saying that fibre helps move waste through your intestines. It certainly doesn’t constipate. Constipation comes from the Latin word constipare (to crowd together) and we have all experienced it on occasions, such as when travelling or we have a dramatic change in our diet.

The fibre travels past your stomach and small intestines because, generally speaking, it doesn’t get digested. Then it slides into the large intestine which is teeming with super-helpful and enthusiastic bacteria. These bacteria just love fibre. They will eat fibre all day, reproductively divide with big smiles, while producing compounds that kills bowel cancer cells. It is all those bacteria that make your waste soft and easy-to-pass. (No, fibre doesn’t act little a bottlebrush to scour out your insides; fibre is good for you because it feeds the healthy bacteria within.)

RESISTANT STARCH

The banana is smarter than just providing fibre. It is the only fruit to give us resistant starch. For a long time we thought that fibre was pretty much the only thing in food that did the job of making our waste wholesome, soft and bulky. Now we know that resistant starch (RS) is having a similar effect. It is not really fibre as we know it, although, like fibre, it doesn’t get digested and so the RS ends up in the large intestine. That is, RS is resistant to digestion.

Sometimes RS is called a “prebiotic” because it is used as a food source by the bacteria, much like inulin which is often added to foods claiming to have “prebiotics”. Inulin occurs naturally in foods like the banana and asparagus, garlic, artichokes, leeks, onions, wheat, barley and rye. Foods with overall high levels of RS include unprocessed whole grains, legumes, green bananas, and cooled, cooked potato (think potato salad).

RIPENING TO SWEETNESS

As a banana ripens the (long chain) starch begins to form (short chain) sugars making it sweeter and the RS levels decline. Despite that, about 85 per cent of the remaining banana starch eaten makes it to the appendix where the large intestine begins. That’s why both ends of your digestive system love bananas.

CLEARING CONSTIPATION

It is often said that too little water is the cause of constipation and drinking more water will relieve the problem. There is little evidence for this idea, as that implies that humans are frequently dehydrated. Most humans easily meet their daily fluid needs because thirst tells them that a drink is required. True dehydration is experienced only by those who sweat heavily and fail to replace the lost fluid quickly enough. This is most common in athletes and those working in hot conditions for a long period.

The best advice you can give anyone who gets constipated is to do two things: 1) Eat more foods with natural fibre, starting with a banana a day, and extending to wholegrains, vegetables and other fruit; and 2) get active because movement helps waste move through the intestines, especially walking or running-based activities.

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Finger-tip rots of banana fruit

The fruit disease cigar-end rot is very often confused with another disease called tip-end rot. By Lynton Vawdrey, Qld Department of Employment, Economic Development and Innovation.

CIGAR-END WHICH IS caused by the fungus Verticillium theobromae is a firm dark decay of fruit which extends uniformly back from the tip of the fruit.

This infected fruit tip tends to shrink and become somewhat rounded in contrast to the angular shape of unaffected immature fruit.

The infected tip of the fruit eventually becomes covered with an ashy grey coating of fungal spores and resembles the burnt end of a cigar (Figure 1).

Generally only a few fingers per bunch are affected.

Tip-end rot or black-tip disease affects banana fruit during the summer months and tends to be predisposed by an injury such as sunburn at the tip of the fruit.

Late in 2011, some far north Queensland growers raised concerns regarding the high incidence of tip-end rot of fruit at a time when fruit was fetching a high price at the market.

Samples of affected fruit were received and diagnosed at the Department of Employment, Economic Development and Innovation (DEEDI) plant pathology laboratory, Centre for Wet Tropics Agriculture, South Johnstone.

These samples showed early symptoms of tip-end rot where parts of the skin of immature fruit were at first yellow then blackened as the damage aged. Initially the damage was confined to the peel (Figure 2) but fruit with more advanced symptoms displayed a dry rot of the pulp (Figure 3).

The black lesions which formed at the tip-end of fruit tended to develop more on one side of the finger than on the other (Figures 2 & 3).

It is often confused with cigar-end rot because under conditions of high humidity, the sunburnt surface of the affected fruit will also become covered with the ash-coloured growth of the fungus Verticillium theobromae. This particular fungus is a common coloniser of dead flower parts and leaf trash of banana so spores of the fungus are continually close at hand.

Unlike cigar-end, which generally affects only a few fruit in a bunch, tip-end rot predisposed by sunburn can affect a large number of fruit on many hands in a bunch.

Sunburn damage tends to be more severe where clear polyethylene bunch covers are used.

To prevent sunburn and the development of tip-end rot, growers are encouraged to fold a leaf over the developing bunch.

TOP: Figure 1: Typical symptoms of cigar-end of banana. Image courtesy Diseases of fruit crops in Australia by Tony Cooke.

CENTRE: Figure 2: Fruit symptoms showing yellowing and blackening due to sunburn.

ABOVE: Figure 3: Tip-end rot develops more on one side of finger than the other.