(U.S. Department of Agriculture/Agricultural Research Service photo by David Hall)
By targeting Asian citrus psyllids on an area-wide scale and focusing on several individual properties simultaneously, growers can minimize psyllid movement between groves, reduce HLB transmission and maintain citrus production at a profitable level.
Generally, most psyllid sprays are applied on a calendar or threshold basis, resulting in high-spray frequencies and associated costs. Because of the Asian citrus psyllid’s high mobility, reproductive capabilities and fairly quick generation time, calendar- or threshold-based spray programs have caused many growers to scale back on psyllid control, if not abandon the practice altogether.
To avoid scaling back on psyllid control, Mamoudou Sétamou, professor of citrus entomology at Texas A&M University, recommends implementing a phenology-based control program to reduce psyllid populations at a lower cost. He shared the importance of this spraying method during the most recent University of California Statewide Integrated Pest Management Program Citrus Health Webinar.
According to Sétamou, to successfully implement a phenology-based control program, the first step is to study the citrus tree phenology to determine major flush cycles. Psyllid populations generally increase with flush, so targeting psyllids during peak flush periods is a critical component of keeping their populations at bay.
Once the major flush cycles are identified, the phenology-based spray program should include an area-wide dormant spray during the overwinter period, applied before the first major flush of the year. Also, growers should target their spray applications at the onset of subsequent flush cycles during the active growing season and conduct border sprays between flush cycles when psyllids are present. Growers should proactively monitor for psyllids and other pests year-round.
When tested in the field, the phenology-based spray program resulted in approximately 25 to 35% reduced costs, compared to the costs associated with the standard threshold-based program.
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