Whitefly Numbers Increasing In Cotton

DR. SEBE BROWN

JACKSON, TENNESSEE

I’ve been receiving more calls about whiteflies over the past week. Fortunately, many of the fields are not at economically damaging levels. However, if large amounts of honeydew are accumulating and/or leaves are beginning to yellow, those fields deserve closer attention.

The whiteflies we are dealing with in Tennessee are bandedwinged whiteflies, not silverleaf whiteflies. Bandedwinged whiteflies do not transmit any viruses of economic concern in cotton. Drought-stressed cotton is at the greatest risk of injury, and insecticide applications may be warranted if whitefly populations are increasing plant stress—similar to how we approach aphid infestations.

My colleagues at Mississippi State recently conducted a whitefly efficacy trial. The most effective treatments were whitefly-specific insecticides that are prohibitively expensive and have limited practical utility in cotton production. However, they also observed good suppression with Transform at 1.5 oz/acre. More information on that trial is available here: https://www.mississippi-crops.com/2026/07/31/update-whiteflies-in-mississippi-cotton-july-31-2026/.

In Tennessee, growers have reported good success using 0.75 lb/acre of acephate tank-mixed with a high rate of imidacloprid. As a reminder, Vertento has no activity on whiteflies and may actually flare populations by reducing beneficial insects.

At this point, I’m not overly concerned about our whitefly populations. However, if August turns hot and dry, I would not be surprised if whitefly treatments become necessary in some fields. Any honeydew-producing whitefly populations should be controlled before boll cracking. Honeydew can contaminate open bolls, resulting in sticky lint, reduced harvest efficiency, and potential discounts at the gin.   ∆

DR. SEBE BROWN

UNIVERSITY OF TENNESSEE