Scientists discourage pesticides in fighting armyworm

The army worms that has been invading farms.Photo/Musembi Nzengu
The army worms that has been invading farms.Photo/Musembi Nzengu

Researchers are now discouraging farmers from using synthetic pesticides to control the fall armyworm this season.

In an advisory, the Food and Agriculture Organisation said many of the pesticides used last year are harmful to the environment and are more expensive compared to safer alternatives.

“Older pesticide molecules, banned in industrialised countries, are often still readily available and widely used in African countries. These products put farmers’ health and their environments at risk,” FAO said.

It said the rush for the synthetic pesticides was fueled by panic and not based on a careful analysis of the costs and benefits.


“The good news is that bio-pesticides, including those based on bacteria, virus, and fungus, have been already tested, developed and used successfully in the Americas. FAW’s natural enemies have also proved to be fierce combatants of the fall armyworn,” the advisory said.

Bio-chemicals are produced by nature without any human intervention.

Synthetic chemicals are made by humans using methods different than those nature uses, and these chemical structures may or may not be found in nature.

Nairobi-based International Centre of Insect Physiology and Ecology recommends crop diversity to control the worm.

Icipe researcher Zeyaur Khan proposes the push-pull practice, which entails planting a repellent crop and an attractive trap plant such as nappier grass around the farms. “The napier grass attracts stem-borers and armyworm to lay eggs on it, but it does not allow the larvae to develop on it due to poor nutrition. Very few larvae survive,” he said.

Icipe scientists are also studying indigenous insects and other natural organisms that have been found to attack the worms.

Farmers in America use genetically modified plants and advanced pesticides to control the pests, but these options may be too expensive, and harm the environment and crops.

The larvae form of fall armyworm prefers maize, but can feed on more than 80 plant species including rice, sorghum, millet, sugarcane, vegetable crops and cotton, says FAO.

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.

One farmer in Vihiga, Fridah Kavetsa, says she mixed Chilli powder with ash and sprinkled on the maize funnel. Kavetsa says the pest disappears completely after several applications.

These are some of the homegrown methods researchers are studying before recommending them to farmers.

Other methods of control include use of pheromone traps and hand picking of adults and caterpillars.