Tackling Pests in CUPS

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) recently hosted a field day and seminar on citrus under protective screen (CUPS) and individual protective covers at the Citrus Research and Education Center in Lake Alfred. While CUPS exclude the HLB-spreading Asian citrus psyllids from the structures, other pests can slip through the mesh barrier and cause problems. Lauren Diepenbrock, UF/IFAS entomologist, spoke about some of those pests during the seminar.

A PERMANENT PEST

Among the pests that penetrate the netting are rust mites, which Diepenbrock says are in the structures year-round. They can be managed with things like oils, but good coverage is needed.

“Inside the CUPS, we are seeing these really great canopies,” she said. “We will need to trim those canopies so we can get good coverage for mites and other pests.”

Diepenbrock and colleagues will be starting a new study on canopy management inside CUPS this spring to get a better handle on how to improve chemical coverage on trees.

TWO SEASONAL FOES

“We kind of live with the rust mites, but chilli thrips and Lebbeck mealybug have been our bigger challenges inside of CUPS,” Diepenbrock said. “We’ve been working with growers to build our data and learn more about managing these two pests.

“We tracked the chilli thrips and learned they are not a year-round issue. So, if we can target them when they are active, we can have better management practices and minimize chances for resistance.”

The chilli thrips come into CUPS in the spring with the flush. This is the time to take control measures as the pest is trying to get established.

“Chilli thrips also love weeds, so they are building up on those weeds outside of the CUPS and are drawn into the CUPS by weeds inside the structure,” she said. “So, anything we can do to manage weeds outside and inside the structure is important.”

Diepenbrock is studying various insecticide options to control chilli thrips. She cautions that the pest can develop resistance very quickly, so rotation will be especially important. When the pests are most active in the spring window, applications could be needed every two to three weeks.

“The Lebbeck mealybug continues to be a pain in the butt for CUPS growers,” she said. “The pest takes two to three weeks to develop from egg to adult. Lebbeck mealybugs don’t require mating, which is unfortunate because you can’t get rid of them by killing off the males. And they can continuously reproduce in ideal conditions, which CUPS provides.

“Oils work great for management of the Lebbeck crawlers. That is the cheapest option to manage them. But here again, canopy management and coverage is going to be critical.”