Even with the virtually 100 percent level of HLB infection found in Florida citrus trees, reducing Asian citrus psyllids improves tree health and yield, entomologist Lukasz Stelinski says. Stelinski is a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) professor at the Citrus Research and Education Center.
Stelinski reports that trials the late UF/IFAS researcher Phil Stansly conducted from 2009 to 2015 demonstrated the need for continued psyllid control, even when HLB is widespread. “What was noticed over the course of several years is that there were more boxes per acre harvested when insecticides were being applied than in blocks without insecticide,” Stelinski says. “But all the trees were equivalently infected … Reducing psyllids does improve health.”
Timing of psyllid sprays is important, Stelinski says. He says January and February are good months to spray because psyllid reproduction rates are low then.
Stelinski urges growers to rotate the modes of action of their psyllid sprays. “Rotating is critical” to avoid the development of resistance to the insecticides, he says. “It’s as simple as rotating five modes of action in sequence. There are more than five modes of action available to use. These are all in the Florida Citrus Pest Management Guide. And it really doesn’t matter which ones you start with as long as you rotate five.”
Stelinski adds that biological control is available for psyllids, but that it doesn’t work sufficiently on its own to return to the yields trees produced prior to HLB. “So I suggest integrating a judicious use of insecticides with biological control,” he says. “And this judicious use of insecticides includes these dormant winter sprays and then spraying throughout the year when psyllid populations rise.” He recommends monitoring to know when the populations rise.
This interview with Stelinski is featured in February’s episode of the All In For Citrus podcast, a joint project of UF/IFAS and AgNet Media. Listen to the full podcast here.
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