Bugs Under the Covers

Individual protective covers (IPCs) do an excellent job keeping HLB-spreading Asian citrus psyllids (ACP) out of young citrus trees, showing a 99.6% reduction in ACP compared to control trees. But they don’t provide “one and done” pest control, according to University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) entomologist Lauren Diepenbrock. In fact, IPCs “create a perfect environment for some insect, mite and pathogen pests to thrive,” Diepenbrock stated at a recent field day at the Citrus Research and Education Center (CREC) in Lake Alfred.

PEST PROTECTION
In addition to keeping virtually all ACPs out of young trees, IPCs have numerous other pest control benefits. Diepenbrock reported that:

• Citrus leafminer infestation is 99.98% less in IPCs than in a control treated with monthly insecticide.
• There is reduced incidence of citrus canker in IPCs.
• IPCs, if secured at the base, can prevent tree-damaging lubbers from accessing and defoliating young trees.

PROBLEMATIC PESTS
Diepenbrock said the challenge with IPCs is that other pests get into the covers and cause damage. These pests are problems in IPCs:

• Caterpillars get into IPCs because moths lay eggs on IPC mesh, and neonates are small enough to pass through the opening and drop to the plant, where they feed. Diepenbrock reported that Bacillus thuringiensis is the most effective material that can be used for most caterpillars.
• Spider mites and rust mites have been found infesting IPC-covered trees at populations that require management. Diepenbrock said spider mites will cause defoliation, and rust mites will cause leaf deformation that can lead to defoliation.
• Scales and mealybugs will get into IPCs. Diepenbrock said proactive management will be important to reduce damage from these pests.

SPRAYING CHALLENGES
Diepenbrock said IPCs provide challenges to spraying, noting that penetration by traditional sprayers is limited to outer portions of trees. She said hand sprayers are effective for coverage of trees in IPCs at close range, but they pose a concern for worker safety. Hoop booms would be optimal, but few are in existence regionally, she said. She added that there is a lack of understanding about chemistry degradation under IPCs.

Another UF/IFAS CREC researcher, Arnold Schumann, discussed the profit potential of citrus under protective screen (CUPS), at the field day.

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