Effective Management Of White Fly In Cotton
Author(s): City Air News1. What is nature of damage of whitefly? Both nymphs and adults of whitefly suck the plant sap by feeding on under surface of leaves. It causes damage to cotton plants in two ways. Firstly by sucking the plant...
cityairnews
Aug 24, 2015 12:30
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1. What is nature of damage of whitefly?
Both nymphs and adults of whitefly suck the plant sap by feeding on under surface of leaves. It causes damage to cotton plants in two ways. Firstly by sucking the plant sap and second by excreting the honey dew on which sooty mould grows. Damage caused by direct feeding reduces the photosynthetic activities of the plant. Indirect damage results from lint contamination with honeydew and associated fungi and through transmission of leaf curl virus disease.
2. What are symptoms of damage of whitefly?
Chloratic spot develop on leaves which drop prematurely. It also causes stunting of plants, shedding of fruiting bodies, poor quality lint. Nymphs excrete honey dew which provides substrate for development of sooty mould which blackens the leaf and lint. Affected plants bears less numbers of fruits.
3. What are the favourable conditions for whitefly development?
1. Late sown crop /staggered sowing are at greater risk for whitefly attack on cotton
2. Survival of whitefly on alternate weed host plants
3. High temperature and scanty rainfall situations aggravate the severity of the pest.
4. Survival and multiplication on vegetable and pulses crops
5. Use of un-recommended/mixture of insecticides
6. Faulty spray technology
4. Where does the whitefly survive?
Survival of whitefly on alternate weed host plants: During off season whitefly survives on weed host plants like puth kanda, peeli buti, kanghi buti, datura, gutputna, makoh, bhakra etc grown in orchards, field bunds, waste lands, road side and irrigation channel/canal. It also survives on mustard crop as an adult stage during winter season. From these alternate host plants it migrates to adjoining vegetable crops during spring season and later shifted to adjoining cotton fields.
Survival and multiplication on vegetable and other crops: Whitefly survives and multiply on many vegetable crops like tomato, brinjal, okra, chilli, cucurbits during spring and summer season and alternatively on other crops like moong, mash guara during summer season and from there it slowly migrate to adjoining cotton fields.
5. What are the pest management options available with us?
Cultural control: Whitefly management should be achieved when their populations are at low levels.
1. Grow only recommended varieties/hybrids
2. Complete the sowing from April-15 May. It will help to escape the attack of whitefly to a great extent.
3. Follow the recommended spacing of 67.5 x 75 cm for Bt cotton as closely sown plants attains more height and create favourable micro climate which help to increase the faster buildup of whitefly. During reproductive stage it creates hindrance in spraying in taller plants.
4. Use of recommended dose of fertilizers.
5. Avoid sowing of American cotton (Bt cotton) in or near the orchard.
6. Avoid growing of vegetable crops like tomato, okra, brinjal and pulse crop like moong, mash and guar in or around cotton field to avoid simultaneous build up and spread of whitefly to cotton.
7. Proper management of whitefly on these alternate host crops will help in reducing the carryover of these populations to cotton field.
8. Keep the fields free from alternate weed host plants in or around the cotton field as the act as a host of whitefly. Eradicate the weeds like puth kanda, peeli buti, kanghi buti, , gutputna, makoh, bhakra growing on field bunds, waste land, road side, irrigation channel/canals. Repeat the operation at monthly interval during off season before sowing to prevent its migration to cotton fields.
Chemical control
1. Regular monitoring followed by campaign is effective strategy for management of whitefly.
2. Strictly follow economic threshold levels and spray against whitefly should be done when population reaches 6 adults per leaf in the upper canopy of plant before 10 am or when honeydew appears on 50 per cent of plants,
3. Triazophos 40EC @ 600 ml/acre or Ethion 50EC @ 800 ml/acre are effective against whitefly.
4. In case of severe infestation, spray of Polo 50WP (Diafenthiuron) @ 200 g/acre will effectively control the whitefly.
5. When adult population is low and leaf coverage by the whitefly nymphs on the under surface of leaves are more or when honeydew symptoms appear on the plants, spray of Oberon 240 Sc (spiromesifen) @ 200 ml/acre will effectively control the whitefly.
6. Proper coverage of underside of leaves during the insecticidal sprays effectively reduces the whitefly population.
7. Use insecticides recommended only for whitefly on cotton.
8. If possible all the farmers of village should spray at same time for its effective management.
9. Avoid tank mixing and readymade insecticides mixture of synthetic pyrethorids.
10. Use fixed type hollow cone nozzle for effective whitefly management.
11. Do not use the same insecticide repeatedly.
12. The severity of whiteflies is seen after the crop growth crosses 10 nodes on the main stem. Therefore, the amount of spray fluid while spraying the insecticides should be 125-150 litre/acre for knapsack sprayer.
What is the life history of whitefly?
Female whitefly lays the eggs singly on the under surface of leaves and mostly on the top and middle crop canopy. Each female is capable of laying 120 eggs. The incubation period varies from 3-5 days during spring and summer, 5-17 days during autumn and more than 30 days during winter. The nymphs after hatching fix themselves to the underside of the leaves. Nymphal period varies from 9-14 days during summer and 17-19 days during winter. The pupal period is 2-8 days. The total life cycle range from 14 to 107 days depending upon the weather conditions. There are 12 overlapping generations in a year and pest also reproduces parthogenetically at times.
Date:
Monday, August 24, 2015
