Intercropping controls Striga in maize based farming systems

Intercropping maize was evaluated as a means to reduce Striga emergence and survival and improve overall farm productivity. Field experiments were conducted at two sites in western Kenya from 1996 to 1999 to study the effect of eight different intercrops on Striga populations and crop yield. Factors studied included relay or simultaneous planting of maize or intercrops, ridge and flat planting systems and in-row or between-row planting of intercrops. Mode of planting maize and intercrops (ridge/flat or in/between row planting) did not affect maize grain yield. However, ridge planting improved intercrop yields and reduced Striga densities. Peanut, bean, yellow gram, bambara nut and soybean intercrops produced considerable yields and increased the overall productivity of the cropping systems. The increase in output of farm produce ranged between 40% and 120% depending on the local agro-ecological conditions. Of the most productive intercrops, yellow gram provided the most stable Striga control over years and locations comparable only to cowpea. Peanut, bambara nut, bean and soybean were more variable in terms of Striga suppression in maize depending on the specific agro-ecological conditions. Shading, higher humidity and lower temperatures under the intercrop canopies were most likely the mechanisms which caused the decline of Striga numbers in intercropping systems. Intercropping can be an effective component of an integrated Striga control program compatible with the limited resources of small-scale subsistence farmers. In the long term, however, Striga populations can only diminish if intercropping is combined with handweeding of mature Striga plants to avoid the replenishment of the Striga seed bank in the soil. (C) 2002 Elsevier Science Ltd. All rights reserved.