The Cotton Jassid (Empoasca libyca, Berg.) in the Anglo-Egyptian Sudan, and Experiments on its Control

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Abstract
Empoasca libyca is a major pest of cotton in the northern and western blocks of the Gezira Irrigated Scheme.Distribution of the species of the genus of Empoasca and Erythroneura lubiae is given, together with their food plants in the Sudan.Damage caused by E. libyca is noted; an experiment carried out in 1935/36 showed that Jassids were able to cause such symptoms.The life-cycle shows that the egg and nymphal stages are of short duration (8 days each) and followed by a long adult life (as long as 2 months) in which the female lays her eggs over a long period.A new type of cage was used and is figured.The effect of applications of Bordeaux mixture in reducing the Jassid population and amount of scorch is given as well as physiological data relating to the influence of spraying on different parts of the Jassid-infested cotton plants. It is shown that sprayed plants produced an appreciable increase in the number of green bolls formed and an increase of 11 per cent, in the weight of seed cotton per boll harvested. It is pointed out, however, that Bordeaux mixture has several disadvantages and other more suitable insecticides are being sought.No Sakel varieties as yet have shown resistance to Jassid attack.

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