The Sunday Mail
Peter Gambara
Caterpillars like hiding in the whorl, so farmers should ensure the chemical gets to that part of the plant. Boom-sprayers might not be effective in this instance.
Fall armyworm (FAW) has caused considerable damage, presenting farmers with a headache regarding its control.
The pest was first spotted in Zimbabwe in the 2016/17 cropping season.
It attacks almost all locally-grown crops like maize, sorghum, millet, rice, wheat, cowpeas, groundnuts, potatoes, soyabean and cotton.
It, however, appears to prefer maize and other plants in the grass family.
The FAW has spread to other Sadc countries such as South Africa, Namibia, Zambia, and Malawi.
This season, the attack was more widespread, with farming beginning to feel the damage.
At least 148 000 hectares had been affected in Zimbabwe by March 1, 2018.
There was little knowledge about fall armyworm control when the first attack occurred, especially as the pest resisted available chemicals.
Initially, many farmers confused it with the maize stalk-borer.
Agritex personnel were not well-equipped to provide farmers with answers either and required training on dealing with the pest.
FAW can have several generations per year and its moth can fly up to 100km per night. It is important to understand its life cycle to effectively control it.
The life cycle includes the egg and six-staged growth of the caterpillar, pupa and moth. The eggs are usually laid on the underside of leaves.
The female moth can lay six to 20 egg masses in her life cycle, with each mass having 100-300 eggs.
Hatched caterpillars feed on undersides of leaves.
Caterpillars can spin silken threads that are then blown by the wind, becoming attached to the next plant.
They mainly feed at night, hiding during the day.
Their favourite feeding spot is the whorl of the maize where they continually feed on fresh and tender leaves.
Caterpillars feel protected in the whorl under the cover of curled leaves.
By the 14th day, they will have reached the whorl (inside the funnel), with their consumption causing visible holes on the leaves.
Their activity is evident from the grass that is seen from the whorl.
After a fortnight, the full-grown caterpillar drops to the ground where it burrows some two to eight centimetres before pupating into an oval shape, 20-30cm long.
After another eight to nine days, an adult moth will emerge from the cocoon to restart the life cycle.
While the sight of damaged leaves is disheartening to any farmer, the good news is that maize plants can actually recover significantly from FAW damage.
Damage can reach 50 percent, averaging 20 percent in most cases even if 100 percent of plants are infested.
Crop nutrition is essential.
A well-fertilised, good-looking crop can compensate for foliar damage, but the scale is different with a yellowish, stunted crop.
Heavy rains wash larvae off leaves and drown those in the whorl.
Farmers should avoid late-planting as a maize crop planted in December/January is more susceptible to attack than another planted in October or November.
Staggering crops, if planting in the same area, should also be stopped.
Agricultural extension officers used to teach farmers to stagger crops to avoid “putting all your eggs in one basket”.
The reasoning was if one crop failed, another could reach maturity.
The 2017/18 cropping season is a good example: early-planted crops in many areas suffered from the January dry spell and cob formation took place under dry conditions.
Those who planted late seemed to have got it right.
If you stagger planting, you continue to provide the fall armyworm’s favourite food as one crop breeds the pest for the next crop.
Further, farmers should increase crop diversity rather than mainly mono-cropping maize.
With Command Agriculture’s introduction, a good number of farmers grew maize and nothing else.
Female FAW moths lay eggs everywhere in large monoculture maize fields.
However, the pest will find it difficult to locate maize if it is intercropped with, say, beans, cowpeas or cassava.
This will obviously work remarkably with small-scale farmers who are used to such kinds of mono-cropping.
It will be difficult to implement the tactic with large tracts of maize where combining is needed.
Growing weeds that produce a lot of flowers around maize fields or in-between fields is also encouraged.
Nectar from flowers attracts predators of the FAW.
In addition, Napier grass can be grown around fields. The grass will attract the pest to lay eggs, but its poor nutrition will not enable larvae to develop.
Another way of dealing with the fall armyworm is mechanical control. Farmers visit their fields regularly to scout and crush egg masses and larvae.
They put ash, sawdust or dirt into whorls to suffocate caterpillars while in other instances, lime, salt, oil and soaps have been used.
Lime and ash are alkaline and likely to drain caterpillars of juice.
Ants are natural predators of FAW larvae. In some African countries, the fall armyworm is regarded as edible; the daring can try it for relish!
Then there is the most popular means of control: pesticides.
Most pesticides, besides controlling the fall armyworm, will also kill other non-target organisms and may pollute the environment.
While the Food and Agriculture Organisation discourages pesticides and advocates an integrated pest management approach, farmers, no doubt, compete for the deadliest pesticide.
Among chemicals used locally are Lambda (karate), Ecoterex, Belt, Ampligo, Coragen, Vantex and Super Dash.
As I mentioned earlier, FAW is here to stay until effective control measures are found. This means farmers should adopt well-managed spraying programmes.
Many farmers only act when leaves are under heavy attack. Spraying early is key. Other farmers buy the correct chemical, but mix it wrongly.
For example, if using Lambda to control the maize stalk-borer, the rate is 100ml/ha, whereas when controlling FAW, the rate is 200ml/ha.
Caterpillars like hiding in the whorl, so farmers should ensure the chemical gets to that part of the plant.
Boom-sprayers might not be effective in this instance.
FAO is for farmer field schools teaching farmers to identify the fall armyworm, adopt integrated pest management and control the pest.
Farmer field schools enable farmers in the same area to share knowledge regularly under the guidance of their extension officer.
They should be able to identify the fall armyworm, differentiate it from the African armyworm and stalk-borer, recognise its different stages and understand its life cycle.
In addition, farmers should know other plants that host the FAW and those that repel it.
Knowing the side effects of different chemicals helps, too.
Fao, in conjunction with the Lands, Agriculture and Rural Resettlement Ministry, is training agricultural extension workers.
About 4 721 out of 5 119 officers had been trained by March 1, 2018 while 635 921 out of 1,8 million farmers had been trained.
The initiative is commendable.
Seed houses and chemical manufacturers should join in as training should be intensified. Extension officers are encouraged to embrace farmer field schools as they will reduce their travelling and training budgets.
Mr Peter Gambara is an agricultural economist and consultant based in Harare. He wrote this article for The Sunday Mail
