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Mitigating Fall Armyworm

Fall ArmyWorm blew into Kenya in 2017 so fast that farmers were losing crops before they had even a first idea of how to control the pest. In the following years, losses have fallen, but only marginally. One study of 1439 Kenyan farmers found that those affected by FAW lost 54 per cent of their maize crop to the pest in 2017. By 2018, they were losing 42 per cent.
Now, the worm has been classed as one of the country’s major crop pests.
But in 2020, with the food supply chain disrupted by rains, locusts, and the Coronavirus pandemic, it matters more than ever to save our maize yields from FAW, by ensuring farmers are equipped to control the pest and prevent it devastating maize production, for #EveryCropCounts now more than ever.

How to identify FAW

Fall armyworms have a dark head with a pale, up-side down Y-shape marking on the front and are most damaging when they are three to four centimeters long.
They breed continuously where host plants are available throughout the year. An adult female FAW lays between 100 and 200 eggs on the lower part of the maize leaves. The eggs are covered in protective scales rubbed off from the moth’s abdomen and change from green to light brown before hatching, which takes place after two to three days.
Hatching produces young caterpillars that begin feeding on the leaves immediately. As they grow, the caterpillars change from light green to brown. It then takes them 14 to 22 days to fully mature. The pest has a typical infestation rate of 73 per cent and can cover over 100km per night. 43 of 47 counties in Kenya have now reported the presence of FAW.
The worm feeds on both the leaves and the maize. Feeding by FAW results in semi-transparent patches on the leaves and masses of holes on the maize whorl, as well as a build up of the FAWs’ excrement, called ‘frass’. The pest hides deep inside the cob and starts feeding on the grains. This causes the cobs to rot thus reducing the grain quality and yield.

Correct choice of product to use

The Ministry of Agriculture and the Pest Control and Produce Board (PCPB) recommend the following registered active insecticide ingredients to control the FAW at different stages in its lifecycle. More pest control products are being evaluated to increase the list of products available for farmers to use. The pesticides can be bought at certified agrochemical sellers across the country. Before purchase, we recommend seeking advice from an agro dealer on the appropriate product to use.

Product NameActive Ingredient
1BELT 480 SC Suspension ConcentrateFlubendiamide 480g/L
2ESCORT 19 EC Emulsifiable ConcentrateEmamectin benzoate 19g/L
3HABLE 5 WG Water dispersible granulesEmamectin benzoate 50g/Kg
4MAY 50 EC Emulsifiable concentrateLufenuron 50g/L
5MERIT 150 SC Suspension concentrateIndoxacarb 150g/L
6ORTHENE PelletAcephate 970g/Kg
7ORTRAN 97% WDG Water dispersible granulesAcephate 970 g/kg
8PROVE 1.92 Emulsifiable ConcentrateEmamectin Benzoate 19.2g/L
9RADIANT 120 SC Suspension ConcentrateSpinetoram 120g/L
10RANGER 48% EC Emulsifiable ConcentrateChlorpyrifos 480g/L
11OCCASION STAR 200 SCIndoxacarb 160g/L + Emmamectin benzoate 40g/L
12LOTUS 75% SP Soluble PowderAcephate 750 g/kg
13AMPLIGO 150 ZC Mixed formulation of capsule suspension & suspension concentrateChlorontraniliprole 100 g/L + Lambda-cyhalothrin 50 g/L
14XPAND MAX 92% SG Water Soluble GranulesAcephate 920g/kg
15UMEME TOP 5 EC Emulsifiable ConcentrateLambda-cyhalothrin 50 g/L
16RELAY 150 SC Suspension ConcentrateEmamectin Benzoate 50 g/L + Indoxacarb 100 g/L

Ideal timing of application

It is recommended that application be done early in the morning or late in the evening. This is because the FAW is active at night and sleeps/ hibernates during the day, which makes it difficult to get the pesticide into contact with the FAW.

Other farm management practices that help mitigate the negative effects of the pest include;

  1. Adhere to regional planting schedules; avoid off-season and late planting of maize
  2. Intercrop maize with legumes like beans, groundnut and soy beans as these can help reduce the pest’s spread
  3. Apply all other good agricultural practices, like timely weeding, use of manure and fertilisers to ensure plants stay healthy
  4. Grow maize only during the main season and in the short rains season grow crops that are not alternative hosts to FAW, such as beans, groundnut, cow peas, sunflower, sweet and Irish potatoes.
  5. Avoid planting new maize crops near FAW infested plants
  6. Use FAW monitoring pheromone traps to ensure early detection of FAW invasions on your farm.
  7. Scout weekly after maize crop emergence and take timely action if any FAW damage or signs are noted, such as destroying the egg masses by crushing them
  8. Spray insecticides during early morning or late evening using an insecticide containing any of the above listed active ingredients, targeting the plant growing points (whorls) where the caterpillars hide. Use pesticides in a responsible manner to prevent contamination to the human, livestock and the environment

Community and government support

The Agrochemicals Association of Kenya has trained over 1,000 spray service providers across 16 counties to supply and apply the pesticides for small scale farmers at a small, negotiable fee. The fee is calculated either per unit area, per knapsack, or per day. Farmers can get in touch with aak-GROWto subcontract a spray service provider.
In 2018, the government distributed pesticides to cushion small scale farmers against the FAW through the county governments. But this was a one-time initiative that was carried out when the FAW invasion was at its height. However, the government has also recruited and trained a community based Fall Armyworm Monitoring and Early Warning team (CBFAMEW). These selected early warning forecasters and monitors are tasked with identifying any increasing threat from the pest and alerting farmers to take preventive actions in a synchronised manner that makes it more effective. The government has also distributed leaflets, posters and hosted radio shows on vernacular and national radios to educate farmers on FAW control.

For advice and further information on controlling Fall Armyworm, farmers are advised to contact:

  1. A certified agrochemical dealer within your county.
  2. The Agrochemical Association of Kenya on our Facebook page @agrochem.croplifekenya, Twitter; @CropLifeKenya or contact us at +254 734447777, +254 710447777
  3. The Pest Control and Produce Board on