Researchers at the University of Florida (UF) are working to help growers manage whiteflies, one of the main pests in tomatoes.
Philip Stansly, a professor of entomology at UF, says three management systems researchers are currently examining are UV reflective mulches, beneficial insect releases and new insecticides.
Stansly says the whitefly levels seen in the last season were the worst since the early 90s, so he emphasizes the importance of pest management.
According to Stansly, UV, metalized, reflective mulches have been proven to deflect whiteflies from tomato plants. He says the whiteflies are confused by the light reflected from the mulch below that appears to be sunlight. This causes the insect to be unable to control its flight and find the plant.
Stansly says researchers are also releasing a beneficial insect into the tomato plants that is a predator of whiteflies. The beneficial insect, Nesidiocoris tenuis, or Nesi for short, is first released into the seedlings of the tomatoes before they are even planted.
During the first trial, Stansly says that after Nesi got rid of the whiteflies, the beneficial insects flew away or in some cases damaged the tomato plant. To solve this, researchers added a plant Nesi favored, sesame, into the field. This kept Nesi in the crop and concentrated damage on the sesame, resulting in good whitefly control and only minor damage to the tomato plants.
Researchers have been attempting to use the mulch and the beneficial insect at the same time, to see if Nesi would have the same reaction to the mulch that whiteflies do. In preliminary results, Nesi was not affected by the mulch and was still able to find the crop. Stansly believes biological control with Nesi will be initially adopted by organic growers but ultimately could serve conventional growers as well, especially when combined with UV reflective mulch and compatible insecticides late in the crop if necessary.
Stansly says researchers continue to look for the best insecticides for pest control in fruits and vegetables. He says early control with systemic insecticides in soil is important for making a difference in the crop.
“We were really excited about the addition of Verimark for this use, but unfortunately it’s very expensive. Although, some of the growers are finding it still useful as an early trench,” Stansly says. “They need to stay on the whitefly populations with rotations that will avoid resistance issues and also separate crops in time and space — not leave them in the ground any longer than they absolutely have to. I think that’s always very important. We just urge growers to use their systemic insecticides at planting and again through the drip to reduce early virus infections that are the most damaging to the crop.”
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