Cotton Whitefly

Cotton Whitefly (Scientific Name : Bemisia tabaci)

Host Range : Polyphagous insect. Some of the hosts are puthkanda, gutpatni, cabbage, cauliflower, sarson, toria, melon, potato, brinjal and okra.

Damaging Stage : Nymphs and Adults.

Identification

Adults : Adults are 1.0 to 1.5 mm long, yellowish in colour and dusted with white waxy powder. Wings are pure white.

Nymphs : Nymphs are yellowish white.

Seasonal History : The whitefly infestation remains in cotton more or less throughout the cotton season but the maximum damage in cotton is done during August-September. Higher population has been noticed in dry weather conditions which encourage its population build up.

Economic Threshold : Average six to eight nymphs per leaf. Count the population from three leaves (one each from top, middle and bottom) per plant and take observation at least from 10 plants from the field.

Nature of Damage : Damage is done by sucking the cell sap from the leaves resulting in loss of vitality of the plant. Normal photosynthesis is affected due to growth of sooty mould on honeydew deposited on upper surface of the leaves, consequently the growth of the plant and yield are affected. Cotton white fly also transmits the cotton leaf curl virus and the veins of diseased leaves get thickened becoming cup shaped (up side).

Management : Spray the crop with 250-350 ml dimethoate (Rogor) 30 EC or 300-400 ml oxydemeton-methyl (Metasystox) 25 EC or formothion (Anthio) 25 EC or 40 ml imidacloprid (Confidor) 200 SL, 40 g thiomethoxam (Aktara) 25 WG after mixing in 120-150 litre of water.