By Clint Thompson
Georgia Vidalia onion growers must prioritize thrips control with harvest season approaching. Since thrips vector center rot disease, producers must be diligent in their scouting and insecticide sprays, says Chris Tyson, University of Georgia (UGA) Extension area onion agent.
“February is usually the time we start worrying about thrips, February and March, really. They are the two months out of the season where we’re monitoring thrips and maybe spraying for thrips,” Tyson said. “Thrips are part of the equation for us for disease control. We know they can influence center rot which is probably the disease that we deal with the most and causes the most losses in onions in our area.”
When to Spray
Tyson discussed thrips management during the recent Vidalia Onion Crop and Disease Update. Prior research has indicated that spraying at an average of one thrip per plant can be successful by reducing future populations and the number of spray trips across the field.
There are multiple effective insecticides that producers can utilize. These include Radiant, Exirel and Torac, which provide residual; and Lannate, which has no residual. Pyrethroids are cheap with not much residual.
“Thrips control is really a way to hopefully mitigate or offset center rot. The thrips here don’t do a lot of physical damage to the plant. They’re a vector for the disease,” Tyson said. “From now until harvest, we’re going to try to encourage growers to scout their crop and treat as necessary to hopefully mitigate any potential center rot losses we might see.
“Our research has shown that if we can control them early on at lower numbers, we can do a better job of controlling them overall and reduce the number of insecticide sprays we may have to make during the season. That’s a win-win for everybody.”