Mar 10, 2021Late-season Thrips Management in Lettuce
Controlling WFT with insecticides is the best approach to minimizing cosmetic feeding damage and may reduce spread of INSV within fields. For adults, which can easily be found on the leaf surface, your best choices of insecticide are methomyl (Lannate) or acephate at a high label rate. They are the most efficacious products against adult WFT. Radiant is not as consistently efficacious against adults, but a 7 oz or higher rate will provide the best knockdown and residual control of WFT larvae. Remember, the key to preventing cosmetic damage by WFT is to maintain larval populations at low levels. The cryptic or thigmotactic behavior of thrips often makes them difficult to find on lettuce plants. Research has shown that if you can see a few adults and larvae on the plant, it means that there are likely 10-fold more thrips actually on the plant (hiding near the base of the plant between midribs). This behavior also means that spray coverage is important, particularly with contact insecticides like Lannate. There are other insecticides such as Torac, Minecto Pro, Exirel, Movento and Assail that can provide suppression (50% control or less) against WFT larvae, but don’t expect much activity against adults. For more information on the identification, biology, ecology, and management of thrips on desert produce please visit Western Flower Thrips Management on Desert Produce.
Name pest contest:
What caused this damage to this small watermelon fruit?
To contact John Palumbo go to: jpalumbo@ag.Arizona.edu