Weed problems and control strategies in Kenya

Abstract

Most annual weeds are easily controlled by tillage or with herbicides. However, a few weeds, such as couchgrass (Digitaria scalarum), stargrass (Cynodon dactylon), nutgrass (Cyperus spp.) and Oxalis spp. are very difficult to control. Timely seedbed preparation in conjunction with the use of such herbicides as dalapon have achieved some success against couchgrass and stargrass. Glyphosate appears promising for the control of nutgrass. In small grains such as wheat and barley, weed seed contamination often leads to downgrading or rejection of the produce. On small-scale farms, the main method of weed control is by hand cultivation using the jembe and the panga (cutlass). On large-scale farms, a combination of mechanical, hand and chemical methods is used. Chemical weed control is practised in wheat and barley. In perennial crops, methods of weed control depend to a large extent on farm size. Small holder farmers depend mainly on handweeding while operators of large coffee and tea estates combine good land preparation with chemical weed control. In pineapple estates, use of black polyethylene mulch is a standard practice. From summary.