Whitefly: Bemisia tabaci
Symptom of damage:
- Chlorotic spots on the leaves which latter coalesce forming irregular yellowing of leaf tissue which extends from veins to the outer edges of the leaves
- Severe infestation results in premature defoliation
- Development of sooty mould
- Shedding of buds and bolls and poor boll opening
- It also transmits the leaf curl virus diseases of cotton
Identification of the pest:
- Nymph– Greenish yellow, oval in outline
Pupa- Oval in shape, present on the under surface of the leaves
Adult- Minute insects with a yellow body covered with a white waxy bloom.
Management:
- ETL: 5 – 10 /leaf
- • Avoid the alternate, cultivated host crops of the white fly in the vicinity of cotton crop
• Growing cotton only once a year either in winter or summer season in any cotton tract
• Adopting crop rotation with non-preferred hosts such as sorghum, ragi, maize etc., for the white fly to check the build up of the pest
• Removal and destruction of alternate weed hosts like Abutilon indicum (Thuthi), Chrozophore rottlari (Purapirakkai), Solanum nigrum (Manathakali / Milaguthakali, Chukkittikeerai) and Hibiscus ficulensus from the fields and neighbouring areas and maintaining field sanitation
• Timely sowing with recommended spacing, preferably wider spacing and judicious application of recommended dose of fertilizers, particularly nitrogenous and irrigation management is essential to arrest the excessive vegetative growth and pest build up. Late sowing may be avoided and the crop growth should not be extended beyond its normal duration
• Field sanitation may be given proper attention. Cultivation of most preferred alternate host crops like brinjal, bhendi, tomato, tobacco and sunflower may be avoided. In case their cultivation is unavoidable, plant protection measures should be extended to these crops also
• Monitoring the activities of the adult whiteflies by setting up yellow pan traps and sticky traps at 1 feet height above the plant canopy and also in situ counts
• Collection and removal of whitefly-infested leaves from the plants and those which were shed due to the attack of the pest and destroying them - Chemical control:
• Acetamiprid 20% SP 100 g/ha
• Chlorpyriphos 20% EC 1250 ml/ha - Spray any one of the following plant products alone or in combination with the recommended dose of insecticide (at 2 ml/l of water)
- • Neem seed kernel extract 5% (50 kg) and neem oil at 5 ml/l of water
• Fish oil rosin soap 25 kg at 1 kg in 40 lit of water
• Notchi leaves 5% Extract Catharanthus roseus aaextract 5%
• In the early stages with high volume sprayer, use a gooseneck nozzle to cover the under surface of the foliage to get good control of the pest. If high volume sprayers are not available, 375 litres of spray fluid may be used per hectare for application in the low volume motorised knapsack mist blower
• The use of synthetic pyrethroids should be discouraged in cotton to avoid the problem of whitefly
• Fenvalerate and deltamethrin cause resurgence of whiteflies, so avoid repeated spraying of pyrethroids
• The plant protection measures should be adopted on a community basis in a specified cotton areas - Biological control: Verticillium lecanii 1.15% WP 2500 g/ha.
Source-
- TamilNadu Agritech Portal
