By Clint Thompson
University of Georgia Cooperative Extension vegetable entomologist Stormy Sparks confirmed this week that whiteflies are back with a vengeance on susceptible vegetable crops and Georgia’s cotton, which is still just a few weeks old.
“I’ve been holding off a long time on saying it looks bad. But about a week ago, it’s just hard to say it doesn’t look bad,” Sparks said. “There’s still some things that could happen, but I saw some populations in some cantaloupe that you don’t usually see for another month or two. They’re already treating some cotton, apparently.
“We’re probably a month behind 2017, but we’re at least a month ahead of our normal year.”
Sparks said in May that whiteflies were already present in Georgia vegetables.
Why So Early?
While colder temperatures do not eliminate whiteflies, they do kill many of their wild hosts. They also slow population development in cultivated hosts. Warmer temperatures this winter allowed for larger whitefly populations to overwinter and become mobile earlier.
“We already had the populations, there’s no doubt about that, earlier than normal in some areas, particularly coming out of kale. There’s a lot of things that can happen as far as weather and everything else that can impact it. There’s still some things that could happen to keep it from getting as bad as it did in 2017,” Sparks said. “If they get to a certain level, those rain events don’t have the same impact than they would at lower populations. I think we’re probably far enough long now that they’ll rebound fairly rapidly. That’s what I’m afraid of.”
Rain is expected all week in South Georgia, but Sparks believes a tropical storm-type system is what is needed to suppress whitefly populations.
UGA cotton entomologist Phillip Roberts said farmers are already treating for whiteflies in cotton which is month to a month and a half earlier than normal.
What Can Be Done?
Sparks, Roberts and other specialists continue to preach sanitation with whitefly management. Farmers have done better in recent years in getting rid of their vegetables once they are done harvesting. That needs to continue this summer.
“If the vegetable growers get rid of those crops that are infested, if you’re done with them; if you get done with watermelon fields and cantaloupe fields … get rid of them. Don’t let them keep reproducing. The cotton guys just need to be keeping an eye on infestations and don’t let them build up there,” Sparks said.
Whiteflies migrate from winter vegetables to spring vegetables to agronomic crops, like cotton, to fall vegetables and back to winter vegetables. Whiteflies cause feeding injury issues in vegetables and transmit two new viruses: cucurbit leaf crumple virus and cucurbit yellow stunting disorder virus. Vegetables like squash, zucchini, cucumber, cantaloupe and snap beans are highly susceptible to these viruses.