Lukasz Stelinski makes the case that reducing HLB-spreading Asian citrus psyllid (ACP) populations improves tree health — even when trees already have HLB. The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) entomologist offers several tips about psyllid control in a new presentation available online.
Keeping ACP populations down seems to help yield, Stelinski states. His hypothesis is that plant health is affected by pathogen inoculation frequency. He makes the observation that long-term ACP feeding suppresses plant immunity and inhibits growth, which explains the importance of vector suppression as part of HLB management.
Stelinski offers a typical recent model for ACP sprays, along with a possible better alternative. The typical model involves timing a dormant spray after harvest and before major spring flush using a pyrethroid or organophosphate, then spraying on a schedule with intervals somewhat determined by length of efficacy of a particular insecticide.
The possible better alternative is to spray for adults at bud break at the beginning of each new flush before there is feather flush on which adults can lay eggs. Second sprays on the flush follow as ACP begin to reappear; additional sprays aren’t applied “until ACP reach threshold (0.2-0.7 per tap),” according to Stelinski.
He concludes with a summary of ways to lower ACP control costs and resistance to insecticides. They are:
1. Thresholds can guide spray frequency and reduce sprays.
2. Target control to reduce ACP in flush. Preemptive sprays may be best. Don’t let a standing population linger.
3. Use border sprays to control psyllids where they congregate and reduce sprays to the whole block. Use selective products for whole block sprays and cheap products for border sprays.
4. Conserve beneficials by eliminating unnecessary sprays.
5. Rotate between at least five modes of action.
6. Other techniques (mulches, kaolin, mesh, windbreaks) are available and more are coming (attract-and-kill).
Stelinski’s presentation is one of the first from the cancelled 2020 Florida Citrus Growers’ Institute to become available online. The annual Grower Institute was cancelled because of COVID-19. UF/IFAS is working to make the numerous cancelled presentations available to growers.
Restricted use pesticide license and Certified Crop Advisor continuing education units (CEUs) are available to those viewing the Florida Citrus Growers’ Institute presentations. Get CEUs here.
Obtain more advice from Stelinski on psyllid/HLB control.
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