Simple farming practice that protects maize from striga

Richard Amollo’s small granary in his homestead in Uyoma, Siaya County teems with maize harvested last season.

The farmer harvested six 90kg sacks of maize from his quarter acre after being taught a farming practice in 2013, which eliminates striga, a weed that had denied him a good harvest for many years.

Amollo practices what is known as the ‘push-pull system’, an innovative method in which maize is intercropped with silver-leaf desmodium and napier grass is grown on the border of the farm.

The two fodder crops help to raise yields by curbing striga, stem borer and improving soil fertility. “When I first used the method, I got five sacks of maize from one. Now I get at least six bags every season.”

The push-pull system is an innovation of the International Centre of Insect Physiology and Ecology (ICIPE), Mbita.

Prof Zeyaur Khan, the brain behind the system and the project director at ICIPE, says in the push-pull method, the napier grass planted on the edges of the farm attracts and traps the stem borer moth preventing it from completing the life cycle (pull).

On the other hand, desmodium intercropped with maize repels the striga pest from the crop (push).

The stem borer moths lay eggs in napier grass but since the grass does not allow the larvae to develop into adults, they end up dying.

Desmodium, according to Prof Khan, is planted in between rows of maize. The crop produces a smell that stem borers do not like pushing them away from the maize plants.

“Chemicals released by desmodium roots also control the parasitic weed, striga hermonthica, by inducing abortive germination, providing very effective control of the noxious weed,” he says, adding that desmodium also improves soil fertility.

Normally, once stem borer’s eggs hatch into larvae, they eat up maize or sorghum leaves and burrow into the stem as they grow. The larvae then eats the food the maize or sorghum would use to fill the grains, explains Prof Khan.

Similarly, striga attaches its roots onto the roots of maize or sorghum plant. It then takes the food the maize or sorghum crop gets from the soil starving it.

Omollo gets additional income by selling dried desmodium fodder to dairy farmers at Sh500 for a bale of 15kg.

FINE SOIL PARTICLES

Prof Khan says that push-pull system helps maize and sorghum farmers deal with many challenges that they encounter on the farm.

To grow maize under the system, one starts by clearing land during the dry season.

“Plough and harrow to fine soil particles before the onset of the rains. Desmodium has very small seeds, therefore, the soil should be carefully prepared,” says Prof Khan.

One then plants three rows of napier around farm. The spacing should be 75cm between plants.

Apply one teaspoon of triple superphosphate fertiliser or two handfuls of well-decomposed farmyard manure in each hole before planting napier grass.

Desmodium should be planted in such a way that its rows alternate with maize so that ploughing of the field in the next season will be easy. “Plant your maize in the field already surrounded by napier grass. Ensure that the first row of maize is one metre away from the napier grass. The recommended spacing for maize is 75cm between rows,” notes Prof Khan.

Apply one teaspoon of triple superphosphate or two teaspoons of single superphosphate per hole.

To intercrop desmodium, the crop is planted in between maize rows at 75cm from one row to another, he explains. Using a strong pointed stick, make a furrow 1 to 2cm deep in the middle of the rows where maize will be planted.

Mix the desmodium with superphosphate fertiliser (a handful of seeds and two handfuls of fertiliser). A kilo of desmodium seeds is needed for an acre. If one cannot afford fertiliser, they should mix desmodium seeds with fine sand. Sow it into the furrows and cover with light amount of soil.

“Desmodium should also be drilled on both sides of the outer rows of maize at inter-row spacing of 3.75cm. Plant desmodium with the rains for maximum germination,” says Prof Khan.

“Early weeding is important for the successful establishment of push-pull plot. Carry out the first weeding when maize is three weeks old and second weeding at five weeks.”