How to control fall armyworms using organic methods

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The fall armyworm is a heavy feeder that quickly destroys the maize crop. It can destroy an entire crop if it is not controlled on time. It can spread fast, and can fly over 30 kilometres in one night assisted by the wind.

The fall armyworm (Spodoptera frugiperda) derives the name from its’ feeding habits whereby they eat everything in an area until it is over and the entire "army" then moves to the next available food source. This invasive pest is native to North and South America and Argentina. The fall armyworm larval stage burrows into crops, destroys and eventually kills the plants. Recently, it was identified for the first time in West Africa before extensively spreading to Southern Africa. The fall armyworm has also been reported in parts of Togo, Nigeria, Ghana, Malawi, Zambia, Namibia, Mozambique and Zimbabwe where the pest has already destroyed thousands of hectares of crops. The emergence of the fall armyworm in Uganda was reported last month and it may probably have spread to some areas of Western Kenya.

How to identify it

To differentiate this larva from other armyworm species, one needs to look at the head of the insect. The fall armyworm's head has a predominantly white, inverted Y-shaped suture between the eyes. Young larvae are greenish or brownish in colour and smooth-skinned.

Mature larvae vary from light tan or green to nearly black. They have three yellow-white hairlines down their backs. On each side and next to the yellow lines is a wider dark stripe. The moths have a wingspan of 32 to 40 mm. They have dark grey, mottled (coloured spots) on the forewings with light and dark splotches (marks), and a noticeable white spot near the extreme end of the worm.

Crops affected

Fall armyworms can feed on almost all types of plants. They prefer to feed on maize but also target wheat, millet, cotton, sorghum, sugarcane, tobacco, potatoes and rice. These are the most common staple food crops grown and consumed in Kenya.

Life cycle

They take approximately 3 to 5 days for the eggs to hatch. Developmental time of the larval stage takes 2 weeks to a month. Pupation occurs in the ground near the plant and usually requires 1 to 2 weeks. The adult female begins laying eggs after 3 or 4 days and lays about 150 eggs a day for 8 to 10 days and between 1500 and 2000 eggs in a lifetime. Within as little as 10-12 days, the worm changes into a moth and moves in groups (swarming) as a young adult which has the ability to cover several kilometers in search of distant, new regions with other fresh crops to consume.

Damage

The pest is very aggressive because while invading a new area, it has few or no natural enemies. The larval stage of the fall armyworm is the most destructive stage. Larvae feed on maize leaves and may attack the tassels and/or ears of maize. Their damage appears as tattered edges and holes on leaves, tassels and/or ears. Severe feeding may look like maize crop that has been damaged by hail stones. The first attack of the fall armyworm's invasion often goes unnoticed, because the small larvae that hatch from egg burrow into plant parts hiding inside. It becomes visible only after close observation and as the larvae develops, but by then, it is too late to save the plant.

Control

Synthetic pesticides are mostly used to control the pest. The chemical sprays however contaminate the environment and cause major health risks to humans, livestock and biodiversity especially the non-targeted organisms. Other methods of control include use of pheromone traps and hand picking of adults and caterpillars, use of parasitoids, predators and natural enemies. Cultural control measures also used include management of broad leaf weeds and rapid disposal of crop residues after harvest.


Use organic products to control armyworms in your farm

Farmers in East Africa are currently going through a difficult period with the invasion of the fall armyworm. The worm has spread to the region just when they have planted maize and other crops. The lack of rains and the increased temperatures provide the right conditions for the rapid multiplication of the fall armyworm and other pests.

As usual, many farmers will rush to buy chemicals to control the pests but as we have explained above, most of the pesticides available in the market are not effective against the pest because they will kill the larvae and leave the eggs, which later hatch and continue damaging the maize. This is one reason why the pest is very difficult to control.

However, farmers in Western Kenya have discovered that organic control methods are much more effective in control of the armyworms. Below are some of the biopesticides farmers can use to control the fall armyworms and other pests in maize and other crops:

Nimbecidine®- This is a neem-based biopesticide that can control the fall armyworm, aphids, leaf miners , mites, whiteflies, thrips, wireworms and even n e m a t o d e s in maize, cabbages, potatoes, beans and any crop that is under threat from pests. One characteristic of this biopesticide is that it is an antifeedant meaning that the pest cannot be able to feed on the target crop. Nimbecidine also interferes with the pest’s ability to lay eggs.

Pyrethrum - The white flowers in pyrethrum have active ingredients called pyrethrin. Farmers who opt to use pyrethrum can pick the flowers on a warm day when the flowers are open, dry and store them in an airtight container in the dark (light reduces the effectiveness of the flowers). Later the dried flower can be ground into powder.

Preparation of pyrethrum extract

Mix 20g of pyrethrum powder with 10 litres of water. Add soap as a spreader and sticker and apply immediately especially in the evenings when the armyworms are active. Like neem, garlic has anti-feedant properties and can also repel most pests.

Preparation

Mix 85g of crushed garlic with 50ml of vegetable oil. Add 10ml of liquid soap (use bar soap). Allow the mixture to stand for 24 hours. Mix 50ml of the garlic and vegetable oil emulsion with 1 litre of water (or make enough fill a 20litre knapsack sprayer by multiplying the same amount by 20) shake thoroughly before spraying preferably in the evening when the armyworms come out to feed.


A simple way to control fall armyworm

Fridah Kavetsa is a farmer in Mushiega Village in Vihiga County. After planting maize in her 2-acre farm, she noticed a strange worm that was destroying her maize faster than other armyworms. As she had done before, she went back home and prepared ash and bought chilly powder, which she sprinkled on the maize funnel. After several applications, Ms Kavetsa noticed the pest had disappeared. Other farmers in the village who had resorted to using paraffin and detergents in a desperate attempt to control the pest have emulated her and are now using wood ash and chilli powder with good results.

Apart from Fridah and other farmers, scientists have already confirmed the effectiveness of using ash and chilli powder to control the fall armyworms in maize. The method is better than the use of chemicals in controlling the pest including the fall armyworms.

Here is how other farmers can do it:

• Buy ripe chilli powder (pepper) from the market or prepare your own using ripe pepper.

• Dry the pepper and make powder by either grinding or pounding, remove the big particles and leave the fine powder.

• Sieve cold wood ash from the fireplace.

• Get 1 tin gorogoro (2kg tin or plastic) of ash.

• Mix 1 gorogoro of wood ash with 5 teaspoonfuls of chilli powder.

• Mix the chilli and woods properly by shaking them in a container.

• Put the mixture in a used pesticide container that has small holes.

• Apply the mixture from the container by shaking it once into each plant funnel.

For good results, apply the mixture immediately you see the worms in the maize and repeat the same if you notice any pests in the maize or pest damage to your crop.

Note: In the case of severe infestation, farmers can use the ash and pepper mix other biopesticides to control the fall armyworm.

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