Walls consisting of insect-proof screen held up by telephone poles hold promise for helping growers reduce the cost of controlling HLB-spreading psyllids. The walls serve as artificial windbreaks in a new model grove planted in June at the Citrus Research and Education Center (CREC). The grove was one of numerous projects viewed by more than 500 attendees who came to celebrate CREC’s 100th anniversary on Nov. 29. The CREC is part of the University of Florida’s Institute of Food and Agricultural Sciences.
CREC Director Michael Rogers describes the walls. “We have taken the idea from the CUPS (citrus under protective screen) project that Dr. Arnold Schumann has been working on,” he says. “It’s very similar to that (CUPS), but the difference is we don’t have a roof on it. So it’s basically a 20-foot wall around the grove that actually prevents psyllids from just flying straight in. There have been some studies that we’ve done that show that psyllids typically fly at the height of the citrus tree canopy at the top. And very few psyllids would fly 20 feet in the air, or 30 feet.”
Researchers are hopeful the walls can reduce psyllid populations by 90 percent or more. If so, Rogers says, growers could use the walls to reduce insecticide costs and slow the rate of HLB spread in new tree plantings. Researchers monitored psyllid populations inside and outside the walls. In early results, Rogers says, “We saw about an 80 percent reduction in psyllid populations inside the wall compared to outside. And so that was fantastic.”
However, in September, “Hurricane Irma blew down the west wall of this structure, so we went for about four weeks where psyllids were moving in and out at will,” says Rogers. “So we probably had a lot of psyllids spreading the (HLB) pathogen inside the area during that time. But overall, it seems to be working fairly well.” Researchers continue to monitor the effectiveness to see if the walls might provide growers with another psyllid control option.
“Over time, the cost (of the walls) is actually going to be less per year than insecticide-application programs,” Rogers says. The per-acre cost of the walls declines as acreage size increases.
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