US (GA): Whitefly populations troubling vegetable growers
Coolong said growers must be up to date on spray programs, though combating whitefly populations of this magnitude will still be difficult. In some cases it might be impossible to to stop whiteflies before they spread viruses.
An adult whitefly feeding on a tomato leaf. Picture taken by Saioa Legarrea/UGA.
“Spraying for whiteflies multiple times per week has been somewhat effective,” Coolong said. “There are a number of products out there that can be injected through drip irrigation or sprayed, but even those methods have their limits. When growers do see viruses, they need to be aware and be able to identify (the viruses).”
“Aside from silvering of leaves in cucurbits, whiteflies cause irregular ripening of tomatoes, which reduces market value and is only evident after harvest,” Srinivasan said. “The most important thing, however, is that they can actually transmit viruses.”
Cucurbit leaf crumple virus and tomato yellow leaf curl virus are the two most common viruses transmitted by whiteflies this year.
There are some ways to mitigate feeding damage, according to Srinivasan. He said that growers could use reflective mulch to make it harder for the whiteflies to land on the plants. The seedlings can also be drenched with insecticides before being planted.
Srinivasan said that climate and weather patterns are huge reasons why whitefly populations are so high. He said the warm winter and lack of rainfall in early summer could be reasons for this explosion.
“The problem with managing whiteflies on vegetable crops is that you’re operating with a zero threshold,” Srinivasan said. “We can’t afford to have any whiteflies at all. It only takes one whitefly on a plant to transmit the virus.”
Source: University of Georgia