grasses protect kenyan maize from stem borer peril

The stem borer worm is one of the two biggest afflictions to Kenyan maize farmers, besides the aflatoxin fungi, knocking out as much as four-fifths of the crop. But as debate rages over the merits of rolling out genetically modified seeds resistant to the worm, agriculturalists report the problem can be nearly eradicated through simple inter-cropping.

According to the Kenya Agricultural Research Institute (KARI) and the International Centre of Insect Physiology and Ecology (ICIPE), the stem borer worm can be responsible for up to 80 percent yield loss amongst Kenyan maize farmers.

The scale of the damage has seen the organisations working to develop both conventional and genetically modified maize breeds resistant to the worm. The GM research is being funded by the Bill and Melinda Gates Foundation, but is in development stage, said Dr Philip Leley of KARI maize division at Muguga. “We are waiting for funds to continue to the next stages.” 

However, the ICIPE and KARI researchers have meanwhile found a new way to protect maize, in a technique they are calling “push pull”, where silverleaf desmodium a fodder legume, is intercropped with the growing maize, napier and Sudan grass.

For farmers who have adopted this method, some have reported a six-fold increase in their maize yields, as well as extra income from selling the napier grasses as animal feed.

The push-pull cropping technique works by exploiting the natural relationships that exist between plants and insects. The silverleaf desmodium produces a scent that repels (push) the stem borer. The borer then gets attracted by the Sudan grass scent and they lay eggs on the grass rather than on the maize stalk.

At the same time, the napier grass produces a sticky gel that traps the stem borer larvae on hatching. The effect is a significant reduction of larvae that would otherwise have matured to adulthood and attacked the maize. 

The napier grass is planted around the maize field to form a perimeter. The desmodium fodder and Sudan Grass are planted side by side with the maize. The push pull technique has been a success with over 3000 farmers in Central Kenya’s maize growing regions.

It has been a timely technological breakthrough, with rules still to be formulated by the

Bio Safety committee governing the eventual release of genetically modified maize breeds commercially. Currently, no genetically modified maize has yet been authorised for commercial use in Kenya.

Written By James Karuga for African Laughter

• < Prev
• Next >