Late-season cotton fields can face pressure from several insect pests at once, including whiteflies. These small, sap-feeding insects live and reproduce on the undersides of cotton leaves. While several whitefly species can be found in cotton, silverleaf whitefly deserves special attention because heavy populations can reduce yield, contaminate open lint with honeydew and contribute to sticky cotton.
By late summer, cotton scouting often shifts toward protecting open bolls and preserving fiber quality. That is also when silverleaf whitefly populations can build quickly, especially from late August into September. At first glance, a whitefly attack on your cotton crop may look like a minor nuisance. But when populations build during boll opening, they can create problems that follow the crop all the way to the gin.
How to identify silverleaf whiteflies in cotton
Adult silverleaf whiteflies are tiny insects that resemble moths and are usually found on the undersides of cotton leaves. When disturbed, adults often flutter into the air before settling back onto the plant. At rest, they hold their white wings roof-like over their yellow bodies.
Silverleaf whitefly eggs are tiny, oval and usually found on the underside of leaves. After hatching, the first immature stage, often called the crawler, moves a short distance before settling on the leaf surface to feed. Later immature stages remain mostly stationary and can look like small scales attached to the leaf.
One of the easiest immature stages to recognize is the “red-eye” stage. These nymphs are oval and yellowish, with two distinct red eye spots. Finding both adults and immature stages on the undersides of leaves is a sign that silverleaf whiteflies are reproducing in the field, not simply moving through.¹
Cotton whitefly damage symptoms to watch for
Silverleaf whitefly populations often become more of a concern as cotton bolls mature and begin to open. If populations build high enough, silverleaf whiteflies can reduce plant vigor and contribute to premature defoliation during the middle and late part of the season.²
The bigger late-season concern is honeydew. As silverleaf whiteflies feed, they excrete honeydew that can collect on leaves and open lint. This sticky residue can support the growth of black sooty mold, which can stain lint and reduce fiber quality. When cotton whitefly honeydew contaminates open bolls, it can also contribute to sticky cotton, a quality concern that can complicate processing.
Management tactics for whitefly in cotton
Heavy cotton whitefly infestations can reduce yield, so scouting should focus on more than the presence of adult whiteflies in cotton. Growers should also look for immature silverleaf whiteflies on the undersides of leaves, shiny or sticky leaf surfaces, sooty mold and signs of lint contamination as bolls begin to open.
To scout for silverleaf whiteflies, examine the fifth main stem leaf below the plant terminal. Check 30 leaves at random across the field, carefully turning each leaf over to look for adults, nymphs and eggs. A leaf is generally considered infested when it has at least three adult whiteflies. If 40% of sampled leaves, or 12 out of 30 leaves, are infested, treatment may be justified.³
Nymph counts can also guide treatment decisions. If nymphs are present at threshold levels, an insect growth regulator (IGR) may be appropriate, as IGRs disrupt the whitefly life cycle by preventing immature stages from becoming reproductive adults. If adult pressure is high but nymphs are not yet established, growers may need a different treatment approach.⁴,⁵
Cotton whitefly control works best as part of an integrated pest management program. Whiteflies include different biotypes that cannot be reliably identified by sight, and some populations may be less susceptible to certain insecticide classes. Repeated use of the same mode of action can increase resistance pressure, while broad-spectrum applications can disrupt natural enemies that help suppress whiteflies.⁶
By identifying cotton whitefly pressure early and making timely, informed management decisions, growers can better protect cotton yield, fiber quality and crop value through the final stretch of the season.
Experts are available to help you make your crop protection decisions. Reach out to your seed retailer, a nearby extension office agent or a seed company professional like your regional BASF representative.
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Endnotes
- University of California Statewide Integrated Pest Management Program. “Silverleaf Whitefly.” UC IPM Pest Management Guidelines: Cotton, University of California Agriculture and Natural Resources, ipm.ucanr.edu/agriculture/cotton/sweetpotato-whitefly-silverleaf-whitefly/.
- Texas A&M AgriLife Extension Service. “Whiteflies.” Cotton Insect Management Guide, Texas A&M AgriLife Extension Service, cottonbugs.tamu.edu/foliage-feeding-pests/whiteflies/.
- Texas A&M AgriLife Extension Service. “Whiteflies.”
- Texas A&M AgriLife Extension Service. “Whiteflies.”
- “Whiteflies in Cotton – Watch OUT!!” Plow Points, University of Georgia Cooperative Extension, 31 July 2017, site.extension.uga.edu/plowpoints/2017/07/whiteflies-in-cotton-watch-out/.
- University of California Statewide Integrated Pest Management Program. “Silverleaf Whitefly.
