The large-scale Control of the Cotton Jassid in the Gezira and White Nile Areas of the Sudan

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Abstract
The damage caused by the Cotton Jassid to the Egyptian-type cottons in the Gezira and White Nile areas of the Sudan is very considerable. Realisation of this fact has been greatly aided by chemical control of the pest in small-scale experiments, followed by large-scale work with tractor-drawn sprayers and with helicopters fitted with spraying equipment. This paper deals primarily with examination of available records pertaining to the cotton crops in the four seasons from 1946/47 to 1949/50, preceded firstly by an introduction which emphasises the importance of yield records in the appraisal and interpretation of losses from pests, and secondly by an account of certain aspects of the pest in the Gezira Scheme.Large-scale spraying to control the pest started in the Gezira in the crop season 1945/46; yield increases from about 1,250 feddans (acres) sprayed with 0·1 per cent. DDT emulsion were very satisfactory. In succeeding seasons increasing areas were sprayed; in 1947/48 spraying was extended to the cotton farms along the White Nile between Khartoum and Kosti; in 1949/50 the total area sprayed in the Sudan was over 150,000 feddans. Material and also methods and dates of application varied considerably.