Date Posted: April 26th, 2010
Agnes Mbuvi harvested an excellent maize crop this season. Before, she harvested only half a bag from her small plot. This season, she harvested six bags – more than 500 kilograms of maize.
She stands in her field, among the plants that made it possible. It’s not a special variety of maize that did the trick. It was two plants that protected her maize. Ms. Mbuvi planted desmodium between her rows of maize. And napier grass around the entire plot. These two plants managed both stem borers and striga.
Stem borers and striga are two of the most important pests affecting maize in Africa. Stem borer caterpillars tunnel into maize stalks. They weaken the stem so it breaks and falls over. Striga, on the other hand, attacks maize at the roots. It sucks water and nutrients away from maize, stunting growth. Together, the pests are responsible for huge crop losses.
But farmers like Ms. Mbuvi have learned to push striga out of their fields with desmodium and pull stem borers away with napier grass. By strategically using these plants, they are practising the “push-pull” method of pest control.
Farmers start by planting napier grass. At least three rows of napier are planted all around the field. Planting must be completed before the rains. This allows napier to start growing before maize.
Napier does the pulling. It’s attractive to stem borer moths. So moths lay their eggs on napier grass instead of maize. Once the eggs hatch, the grass produces a sticky substance which traps the moths, which then die.
Desmodium does the pushing. Farmers plant desmodium between the rows where maize will be planted. Desmodium is planted with the rains for maximum germination. Three and six weeks after planting, farmers trim desmodium so it doesn’t overgrow the maize.
Desmodium produces a smell that stem borers don’t like. Its roots produce a chemical that suppresses striga. So it pushes out both pests.
Napier grass and desmodium do something else for farmers. They provide good fodder for cattle. This means healthier cows that produce more milk.
Ms. Mbuvi is happy with the results. As a widow, she must produce all the food for her family. She says the push-pull method has ensured enough milk and maize for the year. There is even some surplus to sell. Selling the surplus earns Ms. Mbuzi income to send her children to school.