Grower Response to Psyllid Insecticide Resistance

Ernie NeffPsyllids

psyllid resistance

Lee Jones

Lee Jones was in the Citrus Expo seminar audience recently when a scientist reported there have been incidences of HLB-spreading psyllids being resistant to insecticides. Jones, general manager of Gardinier Florida Citrus, has one recommendation for dealing with the issue, at least partially. “I would really suggest that October to March window as an application window for the imidacloprids (a type of neonicotinoid) because the imidacloprids have got a zero-day PHI (pre-harvest interval), so we can get in there and harvest,” he says. He explains that a zero-day PHI allows harvesters to enter the grove the day after imidacloprid application. He adds, “I think if we all get together and do that as an industry, we can reverse that resistance buildup of the psyllids.”

Jones thinks his recommendation would help growers rotate use of insecticides with different modes of action, a key to preventing insecticide resistance.

Jones says he’s also concerned that numerous growers have reported reducing psyllid sprays in order to allow room in production budgets for bactericide use. He thinks reducing psyllid sprays could lead to increased HLB problems perhaps two years from now.

“I don’t think we’re going to see an immediate result of that (reducing psyllid sprays), because it’s going to take time for the bacteria to build up in the phloem,” he says. “But it’s really concerning about two years down the road, in my opinion, because I think that we could potentially see an increased tree death and fruit drop … if we don’t stay on top of psyllid control.”

Soon after HLB began ravaging Florida citrus groves in 2005, most Florida growers put a heavy emphasis on control of Asian citrus psyllids. Many joined citrus health management areas (CHMAs), which are cooperative efforts to control psyllids by spraying over large areas at approximately the same time with the same materials.

As Jones notes, some have cut back on psyllid sprays in the past year to make room in the production budget for bactericides, which they hope will help reduce the severity of HLB. Many have also reduced sprays because they question the need to continue spraying for psyllids when all Florida citrus groves and most trees are already infected with HLB.

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About the Author

Ernie Neff

Senior Correspondent at Large