By Clint Thompson
University of Georgia Cooperative Extension vegetable entomologist Stormy Sparks said whiteflies are present in Georgia vegetables. This is not good since cotton farmers have begun planting their crop, and whiteflies like to feed on cotton plants as well.
“There’s some. I don’t know if it’s worse or better or whatever compared to other years. Apurba’s been running those traps and checking some fields and he’s finding whiteflies,” said Sparks, referring to Apurba Barman, a postdoctoral researcher under UGA entomologist Michael Toews.
“Apparently, they’ve always been here. But yeah, noticeable numbers in April is early, particularly in any fields. Where he’s finding most of them is kale which is not a good sign. That’s one of the crops they overwinter in. This time of year, having numbers is not good in any crop.”
Why So Early?
While colder temperatures don’t 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.
“They’re able to carry through on crops a little easier. It never really gets cold enough here to really kill them, it just slows them down. Hopefully, the crops we have out there in the winter are not as good of hosts as some of our spring, summer or fall crops. You’re always hoping they’ll crash during the winter. But yeah, the mild winter undoubtedly plays a role in them overwintering a little better.”
Whiteflies cause feeding injury issues in vegetables and transmit two 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. Commercial cultivars that have resistance or tolerance to these pathogens are not available.
Will They Get Worse?
The weather patterns over the next couple of months will determine if the whiteflies continue to worsen. How much rain will there be? How heavy are the rains and when will they occur? This is especially important as farmers move from winter crops to spring crops and then to cotton. Freezes in the winter and a tropical storm-type of weather system really impact populations.
“You never want a tropical storm but a good tropical storm at the right time really knocks them back,” Sparks said.
Sparks and other specialists continue to preach sanitation with whitefly management. He said farmers have done better in recent years in getting rid of winter vegetables once they’re done harvesting. That needs to continue with the spring crops once they’re done.
“If you’ve got crops where you know you’ve got them, if you’re done with the crop, get rid of that crop,” Sparks said. “I think overall we’ve been doing a better job with sanitation. That’s something we always need to hammer on and remind them that sanitation is critical.”