Companion “push-pull” crop system proves successful against fall armyworm in East Africa


By Fredalette Uys | 23 November 2017
fall armyworms; armyworm
Fall armyworms - a picture taken by farmer Gift Mpande on his maize.

A companion planting system for maize originally developed to keep stem borers and striga at bay, has also proved to be successful against the fall armyworm.

Scientists from the International Centre of Insect Physiology and Ecology (Icipe) in Kenya have found that existing push-pull companion planting technology could help smallholder farmers to halt the damage caused by the fall armyworm.

This climate adapted system was initially developed to limit two other problems experienced by African smallholder maize farmers, namely striga and stem borers.

Pesticide use has, so far, been promoted by several governments and agricultural institutes on the continent as a solution, but several issues like pest resistance, inefficient use, harmful effects, high costs, lack of knowledge have proven to be problematic in fighting these pests.

This led Icipe to develop a more integrated pest management (IPM) solution that is suitable and more cost-effective for smallholder farmers.

PUSH-PULL TECHNOLOGY

The method involves intercropping maize with a repellent plant, such as silverleaf desmodium (Desmodium uncinatum), and a plant attractive to the pest, such as Napier grass (Pennisetum purpureum), as a border crop around the intercropped field.

Diagrammatic presentation of push–pull strategy for insect pest management. (Courtesy of Dr. Johnnie van den Berg, North West University, South Africa)

Silverleaf desmodium, a legume also utilised for pastures and feed, acts as the “push” force that repels the insects and the Napier grass fulfils the pull action by attracting the worms away from the maize plant.

The push plants also attract the natural enemies of these insects, which adds another dimension to the deterring properties of the system. Another positive attribute of the silverleaf desmodium is its nitrogen fixing abilities, which aids soil health, also increasing yields.

STUDY

For the study, a total of 250 farmers, who already adopted the use of the technology in Kenya, Uganda and Tanzania, ware selected for the study. Each farmer planted two plots – the push-pull plot and a monocropping maize plot -that were compared.

In their results, the scientists found an 82.7% reduction in the number of fall armyworm larvae per plant and an 86.7 % reduction in plant damage per plot with the push-pull system. Farmers obtained almost 3 times the yield with these systems and indicated their satisfaction with using this solution.

To find more information on the push-pull planting system – visit this website: http://www.push-pull.net/