Push–pull technology is a simple intercropping strategy used for controlling agricultural pests and weeds by using repellent crops as ‘push’plants and attractive trap crops as ‘pull’ plants. This technology is nothing new, it was used by our forefathers to protect their grains from locusts, borers and plant suckers. This technology has been studied and revived by African scientists in Kenya to control stem borers, armyworms and Striga weeds on cereal crops such as maize and sorghum. How this technology works is that it involves the use of behaviour-modifying stimuli to manipulate the distribution and abundance of insect pests and beneficial insects for successful management. The cereal crop, which will be your economic crop will be intercropped with a repellent crop such as Silverleaf (Desmodium uncinatum) and an attractive trap crop such as Napier grass, Bracharia grass and Sudan grass which are wildly distributed in Botswana, with Napier grass being the most effective. To simplify this, Napier grass will be planted as a border crop and within the rows of your economic crop, Silverleaf will be grown. In this way, stem borer female moths will be repelled from your economic crop and simultaneously attracted to your trap crop instead of your economic crop.
The push plant in the intercropping scheme emits volatile chemicals called kairomones which repel stemborer moths and drive them away from the economic crop. The pull plant is always sown along the border, where invading adult moths are attracted to chemicals emitted by the grasses themselves. Instead of landing on your economic crop, the moths head for what appears to be a tastier meal for their offspring.These repellent and attractant crops do not interfere with the growth of your economic crops. There are other benefits of this push-pull strategy, for example, Silverleaf improves soil quality by increasing soil organic matter content, fixing nitrogen, and stabilizing soils from erosion. It effectively suppresses the growth of Striga weeds and also serves as a highly nutritious animal feed.
Agricultural research scientists in Kenya, Uganda and Zambia adopted this push-pull technology to control fall armyworm in their maize crops. Currently, Zimbabwe, Tanzania, Zambia and South-Africa are conducting studies on how this technology reduces fall armyworm infestation in their countries. To control fall armyworm, Greenleaf Desmodium was used as a repellent crop (intercrop) and Bracharia grass (variety Mulato) was used as an attractive trap crop (Border crop). What they also discovered is that not only did it control fall armyworm, it also controlled maize ear rots and mycotoxins, improved soil health and provided high quality fodder for livestock. They also reported that this method reduced fall armyworm infestation by 90%. Crop-livestock integration is made easier with this technology, allowing farmers to diversify their income streams. Push-pull technology isn’t just for cereal crops; research are also underway to see if this technique might be used to reduce tomato leaf miner infestation in tomatoes. This technology does not utilize pesticides and is environmentally friendly, making it a smart farming practice.If you wish to implement it in your farm, please get in contact with a qualified agricultural entomologist who will assist you with correct implementation. Happy farming!
