Psyllid Management Tactics Discussed

Control of HLB-spreading Asian citrus psyllids (ACP) can be enhanced with dormant winter sprays and a focus on spraying grove perimeters, according to Citrus & Specialty Crop Expo presenter Jawwad Qureshi. Qureshi is an associate professor of entomology at the University of Florida Institute of Food and Agricultural Sciences Southwest Florida Research and Education Center.

DORMANT SPRAYS

In making the case for dormant sprays, Qureshi pointed out that ACP adults overwinter, and most young shoots are produced starting in the spring.

He stated that dormant winter sprays reduce psyllids significantly, adding that additional sprays are needed to manage the pests in the growing season.

GROVE PERIMETERS

To make the case for a focus on grove perimeter sprays, Qureshi presented evidence of spatial niche occupation by ACP in Texas citrus. That evidence was that:

• There are significantly more psyllid infestations in the grove perimeter.
• Infestation started from border trees, where possibly one generation is completed before inner trees become infested.
• ACP densities decreased significantly with increasing distance from the grove edge.

Qureshi reported that perimeter sprays kill psyllids, while untreated grove interiors provide refuge for natural ACP enemies. Focusing on perimeter sprays can provide integrated and sustainable psyllid management at reduced cost, he stated.

The researcher wrapped up his case for perimeter spays with the following points:

• ACP showed a strong preference for perimeter trees.
• Predators and parasitoids were common in the perimeter and interior of blocks.
• Psyllids suffered similar levels of natural suppression in the perimeter and interior.
• The higher concentration of ACPs in the perimeter than in the interior of the blocks and the influence of biological control in both zones suggest that spraying the perimeter will be a useful tactic for suppressing psyllids while sparing the interior as a refuge for beneficial organisms.

See Qureshi’s full Expo presentation here.