Addressing California Red Scale in the San Joaquin Valley

Brian GermanCitrus, Industry, Pest Update

Citrus producers are working to address California red scale populations, as second-generation crawlers have emerged in the San Joaquin Valley. Cooperative Extension Area Citrus IPM Advisor, Sandipa Gautam said their tool for tracking degree days in Kern, Tulare, Fresno, and Madera counties can be a helpful resource for growers. Gautam explained that the hot and dry conditions are exceptionally conducive for red scale populations and that it is everywhere at the Lindcove Research and Extension Center.

Red Scale

“In the last weeks, we have had enough degree days accumulated for the crawlers to complete development and hatch,” said Gautam. “We have crawlers and whitecaps right now and because they are at the most susceptible life stage to insecticide applications, this is the perfect timing to make a spray application if you have red scale in your block.”

Some growers saw heavy populations of red scale at the end of last year, and later applications of Movento helped to bring populations down. Growers that have also been deploying mating disruption over the past few years are reporting lower populations in their orchards this year. “If you didn’t apply Movento at the end of the season last year, or did not make that first-generation spray application, you may want to go walk your block and see what kind of populations you have. Or check your trap cards and make a decision based on that,” Gautam explained.

Degree day units can differ from orchard to orchard and can depend on how blocks are oriented. A temperature monitoring unit can help growers with more site-specific data for the accumulation of degree days. As the season moves on, Gautam encourages growers to provide information about their experience with red scale management this year. “Feedback will help me design what kind of research questions I need to answer and what kind of information I need to be putting out during the extension meetings,” Gautam noted.

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Brian German

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Ag News Director, AgNet West