Psyllid spraying was the topic du jour at a recent citrus health management area workshop in Immokalee. The workshop was organized by Ron Hamel, the Gulf Citrus Growers Association’s Executive Vice President, and Mongi Zekri, a citrus Extension agent with a multi-county designation. Phil Stansly, an entomologist with the University of Florida, presented on psyllid spraying at the workshop, according to a Citrus Industry Magazine article. See a summary of it below.
Psyllid Spraying: the Edge Effect
Psyllid spraying is one of the leading ways that Florida growers are using to control the spread of citrus greening, also known as HLB. The Asian citrus psyllid is a miniscule insect that spreads the citrus greening bacteria, thus spreading citrus greening. If all the psyllids are killed or kept at bay, then they cannot infect citrus trees.
Stansly spoke on the Edge Effect, where for reasons yet unknown Asian citrus psyllid populations are higher among the perimeter, or edge, of citrus groves. At the workshop, Stansly said, “The edge effect is real. I think every grower can see it…It’s the fact that we see higher numbers of psyllids around the edges of the blocks, especially when they’re facing an open area.”
Stansly also shared his own theory on the causes of the Edge Effect: “I expressed the opinion that it’s psyllids that are flying out of the block, but they stop when they see that there’s no more trees … We think it has to do with psyllid behavior and the visual response to not seeing trees.”
Psyllid Spraying: Dormant Sprays
Stansly also discussed dormant spraying, which the next coordinated grower spray in the Gulf citrus-growing region will be. “The trees are dormant now and that’s what we’re looking for,” Stansly said. “The advantage to that is that psyllid populations are now decreasing because there’s no reproduction; there’s no flush. Also we’re looking at some pretty dry weather here so we ought to be able to keep the residual in long enough to kill those psyllids.”
He maintained that dormant sprays were successful for growers. “We started experimenting with that (dormant sprays) in 2006 and we saw how effective it was, that a single dormant spray was still effective well past the spring flush,” he said.
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