NATURE AND IMPORTANCE OF WEEDS, PESTS AND DISEASES IN SMALLHOLDER VEGETABLE PRODUCTION IN KHARTOUM

About 90 % of the farmers work full time on their farms of which about two third are of the size of 6 feddan (2,5 ha) or smaller. Quite often the farms are managed on a tenant system with yield sharing. Vegetables are marketed mainly through retail sellers on the market. Almost all farmers employ farmhands, predominantly for weed control and harvest.

Insecticides are applied regularly. About 40% of the farmers are still using a bunch of weeds as a means for insecticide application. No herbicides and fungicides have been used so far. Beside other crops, eggplants and tomatoes are one of the main targets for insecticides. This corresponded well with the information given by the farmers that aphids, jassids, caterpillars and white flies are the major problems in these crops. The survey showed similar results.

Diseases and small pests (e.g. spidermites) were mostly unknown and their symptoms often related to other reasons. The survey instead clearly indicated a higher priority for this group of organisms. Powdery mildew in cucumbers for instance caused losses in yield of up to 27 %. Mildew control accordingly, resulted in an increase of the gross margin from 260 to 360 Sudanese pounds/feddan.

Weed problems in general seemed much better understood. Dominating specimens named by the farmers like Cynodon dactylon and Cyperus rotundus were confirmed by the survey. Farmers considered weeds as one of the most serious problems. Insufficient weed control may reduce yield from 36 up to 80 % as trials in jew's mallow and eggplants demonstrated. Timely weed control not only secured the yield but also reduced the weed pressure

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