Biological control of Striga hermonthica in Kenya, first results of a new seed coating technology

Abstract: Witchweed (Striga hermonthica) is a parasitic weed that causes high yield losses in maize on more than 200,000 ha in Kenya alone. A new biological herbicide developed in Kenya called Kichawi Kill™ is able to control Striga effectively. It is selfproduced in the villages using a secondary inoculum provided by Toothpick Company Ltd. The formulated product has some disadvantages, which are a complicated production process, a very short shelf life and high application rate. Additionally, the product has to be applied manually and therefore can only be used in manual production, leaving out the opportunity for farmers of using mechanization. For this reason, efforts have been made to formulate the active ingredient Fusarium oxysporum f. sp. strigae strain DSM 33471 as a powder and to use it as a seed coating agent. This work deals with the production of a Fusarium spore powder, its properties, its application to the seed, and its herbicidal effect demonstrated in a first field trial under practice conditions. Seed coating tests conducted on 25 striga infested small holder farms spread out in six counties of western Kenya reported yield increases of up to 88 %.