In 2017, Georgia cotton and vegetable farmers had an estimated $200 million in crop losses attributed to whiteflies, according to Dr. Apurba Barman, a researcher for the UGA College of Agricultural & Environmental Sciences (CAES).
This explains why whitefly research was a hot topic at the Southeast Regional Fruit & Vegetable Conference held in Savannah Jan. 10-13.
UGA Extension Entomologist Dr. Alton Sparks Jr. shared the progress CAES researchers are making to control whiteflies in Georgia crops. Sparks said all samples of whiteflies submitted in the last three years from field infestations in Georgia have been identified as the silverleaf whitefly biotype B. But researchers have their eyes open for the appearance of pesticide-resistant biotype Q in Georgia, which has been identified in Florida infestations dating back to 2016.
Because so many Georgia crops serve as hosts for whiteflies, Sparks said whitefly infestations are cyclical. Cotton, squash, broccoli, cabbage, mustards, kale, woods, and grass are all types of vegetation found in Georgia that serve as habitat for whiteflies.
“What happens in spring vegetables affects cotton and what happens in cotton affects fall vegetables. We’ve got to emphasize area-wide control of whiteflies to keep populations down,” Sparks said.
When it comes to choosing pesticides to fight whiteflies Sparks has this advice: “Do not rely on one chemistry. Rotate your chemistry so we don’t end up with product resistance. Pesticides are not getting the effects they did five years ago but nothing does.” UGA researchers are studying various ways to manage whitefly populations and the viruses they spread in crops, Dr. Rajagopalbabu Srinivasan said.
Management strategies researchers are evaluating include: identifying vegetable plants resistant to whiteflies; identifying the best chemical options to control populations; whether mulch and fertilizers can be used to manage populations; and whether growing crops in greenhouses offers protection.
“The best way to manage whitefly populations is by integrating multiple management options. There is no silver bullet,” Srinivasan said.
UGA research shows whitefly symptoms to be less severe in zucchini than in yellow squash, Srinivasan said, and there is some host resistance in snap beans. Varying fertilizer rates (10 lbs. vs. 30 lbs. of nitrogen applied via water drip) to squash and zucchini crops didn’t seem to impact whitefly populations nor did the varying fertilizer rates significantly affect the cull rate of squash and zucchini. However, the study did show that zucchini had a significantly lower cull rate of fruit damaged by whiteflies than squash.