A push pull system is a technique that repels parasitic plants and pests that attach themselves to the crop roots and feed on them.. In push-pull, a cereal crop is intercropped with a leguminous plant like desmodium or molasses grass, while a popular fodder crop, Napier grass, is planted as a border around the field. Desmodium produces volatile chemicals that attract predators of the cereal e.g of maize pests. More importantly, by giving a false distress signal to the moths that the area is already infested, these chemicals ‘push’ the egg laying moths away from the crop to seek out habitats where their larvae will face less competition for food. Napier grass also produces volatile chemicals that ‘pull’ the moths towards them, and then exudes a sticky substance that traps the stem borer larvae as they feed. Few larvae survive. Napier grass attracts stem borer predators. The intercropping is a climate smart practice as it mitigates emission of Greenhouse gases through the reduced need for pesticides. The push-pull system improves food security and boosts farm income.
To effectively implement push and pull systems:
- Step 1: Plant Napier and a legume like Desmodium or molasses grass between every three rows of maize/sorghum as barriers to repel stemborers away from crops.
- Step 2: Plant the Desmodium first as soon as the rains begin, so it immediately repels the stalk borers before the maize/sorghum emerge.
- Step 3: Plant three rows of Naiper grass around the borders of maize field.
- Step 4: Allow pest enemies such as ants and spiders to enter the field to feed on stemborers.
- Step 5: Cut grass and fed to animals as forage.
- Step 6: Abandon areas that are heavily affected by stemborers until treated.
- FAO 2017. PRACTICE BRIEF Climate-smart agriculture Climate-Smart Pest Management: Implementation guidance for policymakers and investors. Rome, Italy.
- The Food and Agriculture Organisation (FAO), 2015. ‘Push-Pull’ fights pests, boosts milk production. Rome, Italy.
- The Food and Agriculture Organisation (FAO), 2002. Land and Agriculture. Rome, Italy.
- The Food and Agriculture Organisation (FAO), 2018. Integrated management of the Fall Armyworm on maize. Rome, Italy.
- Pickett, John & Woodcock, Christine & Midega, Charles & Khan, Zeyaur. (2014). Push-pull farming systems. Current opinion in biotechnology. 26C. 125-132. 10.1016/j.copbio.2013.12.006.
- Push-Pull 2017. Climate-Smart Push-Pull Technology for Food Security, Safety and Environmental Sustainability African Insect Science for Food and Health.
Benefits
- Reduces the need for pesticides.
- Improves food security and boost farmers’ income.
- The green technique deals with trapping the pests (pull) and repelling them (push) by planting Napier and desmodium or molasses grass next to cereal crops.
- The relationship between insect-plant and insect-insect (introducing pest enemies such as ants/spiders) is achieved in order to kill stemborers.
- Grass planted next to crops can be salvaged and used as forage.
Drawbacks
- Naiper grass take up space on the field.
- Cost and lack of availability of Desmodium seed.
- Difficulty in establishing the Desmodium crop, hence practice not suitable for all farmers.
