Whiteflies……What Now?

We knew to be on the lookout for whiteflies in our cotton, soybeans and peanuts based on high populations early in the season. I have had several discussions with Extension Entomologists to learn more about this insect and the implications in our Florida crops. To me, cotton is the simplest; we have scouting thresholds and labeled products. Peanuts appear most challenging; In my experience, we haven’t ever felt like we needed to control whiteflies in peanuts and could rarely find immatures on peanuts in previous seasons. With localized droughts and plant stress, I am questioning our likelihood of success with a do-nothing approach.

Dr. Phillip Roberts, UGA Extension Entomologist has been out ahead of this situation in developing recommendations. He recently shared the following recommendations:

  • Early detection of SLWF is critical for successful management. The presence of SLWF adults in a field or on a farm should influence management decisions for other pests.
  • Use good IPM and conserve beneficial insects. Only use insecticides for other pests when thresholds are exceeded and avoid insecticides such as organophosphates, which are prone to flare SLWF when present.
  • Timely insecticide applications targeting SLWF is a MUST. The goal of SLWF management is to initiate control measures just prior to the period of most rap id SLWF population development. It is critically important that initial insecticide applications are well timed.
  • If you are late with the initial application, control will be very difficult and expensive in the long run. It is nearly impossible to regain control once the population reaches outbreak proportions!

Dr. Roberts also clearly described the physiology of the silverleaf whitefly:

  • SLWF adults resemble tiny white moths. Eggs are laid on the underside of leaves near the terminal.
  • The first instar nymph is called a “crawler” and this is the only mobile stage of the immature SLWF.
  • The crawler moves a short distance in search of a suitable place to feed on the underside of the leaf. The remainder of the immature stages are spent in the same location of the leaf.
  • Immature SLWF are oval and flattened in appearance and yellowish to translucent in color. On cotton during the summer, SLWF complete a generation in about 2 weeks.
  • SLWF adults and immatures feed with sucking mouthparts. Damage ranges from reduced plant growth and vigor, general leaf decline, honeydew deposits on leaves and premature defoliation. Yield reductions can be serious.

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