Whitefly Management in Cotton: Symptoms, Treatment, Chemical, Biological, Natural, and Organic Control

Whitefly is a major pest. White fly has become an economically significant pest in recent years, causing substantial output loss in agriculture, horticulture, and decorative crops with the introduction of Bt cotton. Because of its rapid rate of population build-up, mobility, polyphagy nature, and capacity to spread viral vectors such as Cotton Leaf Curl Virus (CLCV) and propensity to generate black sooty mold on the leaf, it is regarded as a most critical pest from an economic standpoint.

Cotton is a major commercial crop in India, with 9 million hectares produced under various agroecological conditions. It supplies raw materials to the cotton textile industry as well as direct employment for 6 million farmers. Cotton is farmed in ten states in India, which are classified into three zones (north, central, and south). It is also cultivated in tiny areas of other states. In India, 24 insects and mites have been identified as pests that cause considerable output loss. Sap-feeding insects, bollworms, leaf-feeding insects, and mites are among the pests.

Whitefly management in Cotton

The life cycle of a Whitefly

Bemisia tabaci, Known as Whitefly, has four life stages: egg, nymph, pupa, and adult. The female Whitefly deposits her eggs on the underside of leaves, and the eggs develop into nymphs. Before pupating, the nymphs feed on plant sap and go through multiple molts. After about a week, adult whiteflies emerge from the pupal stage. Under ideal conditions, the life cycle from egg to adult can be completed in as little as two weeks, allowing for fast population expansion.

Favorable conditions favoring an increased population of Whitefly in the field

High humidity and moderate temperature, delayed crop sowing, stress caused by lack of moisture, poor quality water, water logging, saline soil, nutrient deficiency, poor weed management, and even higher nitrogen fertilizer application are all conditions that favor the increased whitefly population in fields.

Identification of the Whitefly

Whiteflies have different stages of development: eggs, nymphs, pupae, and adults.
Eggs are yellowish-white, laid on the undersides of leaves, and have a sub-elliptical shape.
Nymphs are yellowish-brown, scale-like, and found in large numbers on the undersides of leaves.
Pupae are similar in shape to nymphs with brownish opercula.
Adults are tiny and white, with a yellow body lightly dusted with a white waxy powder. Females are 1.1-1.2mm long with longer antennae than males, while males are slightly smaller with extended, narrow, and pointed parameres.

Symptoms of damage by Whitefly

Chlorotic spots on leaves merge to form irregular yellowing of leaf tissue, extending from veins to the edges of the leaves.
Premature defoliation due to severe infestation.
Development of sooty mold due to the production of honeydew by whiteflies.
Shedding of buds and bolls, leading to poor boll opening.
Transmission of leaf curl virus diseases, causing further damage to cotton plants. Overall, whitefly infestation can significantly reduce crop yields and quality.

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Impact of Whitefly on Cotton crop

Whiteflies feed on plant sap, extracting nutrients and resulting in stunting, poor development, and defoliation. Due to the deposition of honeydew and the formation of black sooty molds, heavy infestations can also result in boll shed, reduced yields, and inferior cotton fiber quality. Furthermore, whiteflies can transmit plant viruses such as Cotton Leaf Curl Virus, which can further lower crop yields.

ETL management of Whitefly

The Economic Threshold Level for whiteflies is six adults per leaf or more than ten whiteflies discovered in the center of at least 50% of the plants. A smoky look while shaking the plants indicates a whitefly infestation.

Whitefly management in Cotton by cultural method

Avoid alternate host crops near the cotton.
Practice crop rotation with non-preferred host crops
Remove and destroy alternate weed hosts.
Timely sow with recommended spacing and fertilizer application
Maintain field sanitation
Avoid late sowing and extending crop growth.
Monitor whitefly populations with yellow pan traps and sticky traps.
Remove and destroy infested leaves.

Whitefly management in Cotton by biological method

Identify and conserve natural enemies such as parasitoids (Encarsia formosa, Encarsia shafeei, Encarsia sp., Eretmocerus mundus) and predators (Geocoris sp., Zelus sp., spiders, syrphid fly, Chrysoperla, ladybird beetle, dragon, and damsel flies, praying mantis, predatory ants, bugs, and wasps) to suppress whitefly populations.

Whitefly management in Cotton by chemical method

Apply insecticides if the population crosses the ETL level.
Apply recommended insecticides: Flonicamid, Diafenthiuron, Pyripoxyfen, Spiromesifen, Dinotefuran, Buprofenzin, Chothianidine, Ethion.

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Whitefly management in cotton by chemical method

Whitefly management in cotton by organic/natural method

To monitor early whitefly infestations, use low-cost yellow sticky traps (40 per acre).
Maintain clean crop cultivation, keeping fields weed-free for 8-9 weeks following sowing to maintain plant health.
To suppress whiteflies, use Azadirachtin (Neem Seed Kernel Based EC @ 0.15% or Neem Oil Based WSP @ 0.03% 300ppm) at 2.5-5.0 l/ha. To combat whiteflies, use 2.5 liters of homemade neem extract per acre.
Preparation Method: Boil 4-kilogram terminal sections of neem tree shoots, including leaves, green branches, and fruits, in 10 liters of water for 30 minutes, then strain. Filter the substance through a muslin cloth and use the filtrate to spray at the prescribed dosage.
Verticillium lecanii 1.15%WP is indicated against white flies at 2.5 kg/ha in 500 liters of water.
Beauveria bassiana, Isaria fumosorosea, Verticillium lecanii, and Paecilomyces fumosoroseus are all pathogenic fungi.

Preventive measures for control of Whitefly

Yellow sticky traps (20/acre) monitor the field.
Ensure that plant fertilizer is balanced.
The use of broad-spectrum pesticides should be avoided.
Remove any leaves that have eggs or larvae.
Use companion plants that either attract or repel whiteflies
Plant border crops that grow tall (maize, sorghum, pearl millet)
Planting times should be coordinated with neighbors.
When planting, choose a denser plant space. Look for whitefly indicators on new purchases or transplants.
Control weeds and alternate hosts in and around the crop. After harvest, remove plant remains.

Conclusion

Effective whitefly management in cotton involves a combination of cultural, biological, chemical, and natural controls. Techniques include companion planting, intercropping, sticky traps, balanced fertilization, removal of plant residues, and insecticides. Proper monitoring and implementing integrated pest management practices can help suppress whitefly populations and prevent infestations.

Whitefly Management in Cotton: Symptoms, Treatment, Chemical, Biological, Natural, and Organic Control

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