The push-pull strategy in the field

Sustainable solutions to the problems of yield loses caused by stemborers and striga weed; and to the problem of declining soil fertility are best provided by the single ‘Push-pull’ platform technology which simultaneously reduces crop losses; improves productivity and incomes; enables increased production of livestock fodder; addresses soil fertility constraints and enables a minimum tillage system. The technology enables the scaled up production of forage from Desmodium and Napier grass, with integration possibilities into livestock production systems. The technology could also be integrated with soil improvement programmes as it addresses soil fertility problems through improved management and nitrogen fixation by desmodium.

'Pull'

The grasses are planted in the border around the maize and sorghum fields where invading adult moths become attracted to chemicals emitted by the grasses themselves. Instead of landing on the maize or sorghum plants, the insects head for what appears to be a tastier meal. These grasses provide the "pull" in the "push-pull" strategy. They also serve as a haven for the borers' natural enemies. Good trap crops include well-known grasses such as Napier grass (Pennisetum purpureum) and Sudan grass (Sorghum vulgare sudanense). Napier grass has a particularly clever way of defending itself against the pest onslaught: once attacked by a borer larva, it secrets sticky substance that physically traps the pest and effectively limits its damage. The natural enemies lurking among the grasses go into action and dispatch the borers in both maize or sorghum and grass hosts plants.

'Push'

The "push" in the intercropping scheme is provided by the plants that emit chemicals (kairomones) which repel stemborer moths and drive them away from the main crop (maize or sorghum). The best candidates discovered so far with the repellent properties are members of leguminous genus Desmodium spp.Desmodium is planted in between the rows of maize or sorghum. Being low-growing plant it does not interfere with the crops' growth and furthermore has the advantage of maintaining soil stability and improving soil fertility through nitrogen-fixation. It also serves as a highly nutritious animal feed and effectively suppresses striga. Another plant showing good repellent properties is molasses grass (Melinis minutiflora) , a nutritious animal feed with tick-repelling and stemborer larval parasitoid attractive properties.