Healthier maize crop in a push-pull farm

A Platform Technology for Improving Livelihoods of Resource Poor Farmers

Stemborers and striga are the major pests of maize and other cereal crops in eastern and southern Africa. Losses caused by stemborers can reach as high as 80% in some areas and an average of about 15-40% in others. Loses attributed to striga weeds range from 30-100% in most areas in the region. The loss is often exacerbated by low soil fertility. When the two pests occur together, farmers often lose their entire crop. Spraying with pesticides is not only expensive and harmful to the environment, but usually ineffective as the chemicals cannot reach deep inside the plant stems where stemborer larvae reside. Crop losses caused by stemborers and striga amount to about US $ 7 billion annually, affecting mostly the resource poor subsistence farmers. Preventing crop losses from stemborers and striga in eastern Africa could increase maize and sorghum harvests enough to feed an additional 27 million people in the region.

These agricultural production constraints have led to the development of a habitat management strategy known as `push-pull' for the control stemborers and striga weed. The ‘push-pull’ technology has been developed by scientists at the International Centre of Insect Physiology and Ecology (ICIPE), in Kenya and Rothamsted Research in the United Kingdom, in collaboration with other national partners. The technology involves intercropping maize with a repellent plant such as desmodium and planting an attractive trap plant, such as Napier grass, as a border crop around this intercrop. Gravid stemborer females are repelled or deterred away from the target crop (push) by stimuli that mask host apparency while they are simultaneously attracted (pull) to the trap crop, leaving the target crop protected. Desmodium produces root exudates which both stimulate the germination of striga seeds and inhibit their growth after it germinates. This combination provides a novel means of in situ reduction of the Striga seed bank in the soil through efficient suicidal germination even in the presence of graminaceous host plants. Desmodium, which also fixes nitrogen and helps retain moisture through shading, is a perennial crop which is able to exert its Striga control effect even when the host crop is out of season.