Protect Against Whiteflies by Destroying Plants After Harvest

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whiteflies
Photo of whiteflies courtesy of University of Georgia College of Agricultural and Environmental Sciences

By Clint Thompson

University of Georgia Cooperative Extension vegetable entomologist Stormy Sparks says cole crop growers need to destroy their plants once they’re done harvesting this winter. Cole crops, such as cabbage, serve as hosts for whiteflies. Therefore, the crops must to be destroyed once harvest season concludes in order to prevent the risk of a whitefly infestation.

“If you’ve got a crop that’s got whiteflies in it, when you’re done with it, get rid of it. Destroy it. Don’t shoot yourself in the foot,” Sparks said. “Particularly, if you’ve got something where you’ve been battling whiteflies, take it out as soon as you can.”

Whiteflies have piercing, sucking mouthparts and damage plants by feeding within vascular tissues and removing plant sap. The pest causes feeding injury issues in vegetables and transmits two viruses: cucurbit leaf crumple virus and cucurbit yellow stunting disorder virus.

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MIGRATION AND REPRODUCTION
Whiteflies migrate from winter vegetables to spring vegetables to agronomic crops, like cotton, to fall vegetables and back to winter vegetables.

“That’s one of the reasons we have problems with them is because they can go through so many crops throughout the year in South Georgia and they build up in warm weather, and that’s why cotton is a problem. There’s a lot of cotton out there and it’s out there during the hot, dry part of the season when they really like it,” Sparks said. “This time of year, right now, you’re mostly talking about cole crops; cabbage, collards, kale.”

Sparks believes the whitefly issue is not a huge concern right now, especially compared to 2017 when it decimated Georgia’s cotton and fall vegetable crops.

“I don’t think we’re better off or worse off than normal at this point. We’re better off than where we have been in some of our really bad years prior to our emphasis on more of an area-wide management approach. I’d say we’re better off than where we were prior to 2017,” Sparks said.

Whiteflies are difficult to control because of their prolific reproductive cycle. A female can lay between 150 and 200 eggs, and it only takes whiteflies two to four weeks to mature into the adult stage and begin reproducing.

WINTER WEATHER
One factor that could limit whitefly populations is freezing weather. The colder the temperatures get, the more likely they are to kill off the host plants of whiteflies. However, temperatures have remained relatively mild so far this winter. Sparks is hopeful for colder temperatures in February.

“We’d still like to see the cold weather, so we know we’re taking out those other hosts so that we reduce the populations that we carry through the winter,” Sparks said. “We’ve still got a couple of months to go yet, (but) we’re hoping for some winter.”

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