With the help of some local citrus growers, the University of Florida is literally shining some light on Asian citrus psyllids in the hope of making them go away.
Researchers have found that reflective metalized polyethylene film used as mulch beneath newly planted citrus trees causes the dreaded psyllids to become disoriented and impairs their ability to find the host plant. The pests are vectors for huanglongbing—or citrus greening—which has devastated much of Florida’s citrus crop.
Phil Stansly, an entomology professor based at the Southwest Florida Research and Education Center in Immokalee, and graduate assistant Scott Croxton both have had experience with reflective mulch in combating whiteflies and thrips in vegetable fields and thought it might work with psyllids.
They found that the reflective mulch actually provides two benefits for citrus trees.
First, it helps keep the trees free of psyllids.
Second, the mulch—together with a fertigation system that goes with it—helps trees grow more quickly and come into production sooner than they would otherwise.
The first tests were conducted in single plots at the experiment station. Now, the university is testing the mulch on 15 acres, and there are up to additional 25 acres of commercial testing.
In addition to evaluating the effectiveness of reflective mulch, the tests also looked at bare ground, which served as a control, and white-faced polyethylene mulch.
“White face doesn’t repel the psyllids at all,” Stansly says, although it does provide other advantages, such as weed control and moisture and fertilizer retention.
Although testing will continue for at least two more years, Stansly says positive results already have been detected.
“I think that by using the technology, you can delay the onset of greening, reduce the incidence of greening and accelerate tree growth,” he says.
In a summary of the first tests, Stansly and Croxton found less than half as many young shoots were infested with psyllids on young trees growing on reflective mulch compared with trees on white-faced mulch or bare ground.
More than three times as many psyllids were captured by sticky cards between trees on bare ground compared to those on reflective mulch.
In one test, the incidence of HLB was four times greater in trees growing on bare ground and white-faced mulch than on metalized mulch.
The researchers did not use systemic insecticides that typically are used to control psyllids. They believe the rates of infection would be even lower if they had.