How Trunk Injection Is Affecting Psyllid Populations

Research and field trials have been fairly consistent in showing that trunk injection of oxytetracycline (OTC) will reduce the HLB-causing bacteria in citrus trees, resulting in improved yield and quality. But what happens to the Asian citrus psyllid (ACP) when it feeds on treated trees?

The answer to that question is becoming clearer now from research conducted by the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS). Lukasz Stelinski, UF/IFAS entomologist, discussed these observations during a presentation at the recent Florida Citrus Growers’ Institute at South Florida College in Avon Park.

He said research has shown that OTC injections are very effective at reducing HLB bacterial titer in citrus trees for up to 150 days after trunk injection. In addition, the acquisition of HLB by ACP is reduced from 60 to 90 days after application. Stelinski also presented some new data on ACP impacts.

“We have some more recent data just collected in December where we look at non-injected groves vs. injected groves,” Stelinski said. “We had a reduction in the number of infected ACP from 93% in the non-injected to 60% in the injected. So that is a pretty good trend. In places where OTC is applied, the ACP had less HLB bacteria, so that is something to consider for the future, and, of course, you are getting better yields.”

Some growers have reported anecdotal observations that after OTC applications began in their groves fewer ACP were found, along with less ACP damage. Stelinski said the research has not shown fewer ACP in OTC-treated vs. non-treated trees, but the good news is data shows the HLB bacteria in the ACP is reduced.