Growers Addressing California Red Scale

Josh McGill California Corner, Pests

Citrus growers are working to address California red scale populations, as second-generation crawlers have emerged in the San Joaquin Valley. University of California Cooperative Extension Area Citrus IPM Advisor Sandipa Gautam said a 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 the pest is everywhere at the Lindcove Research and Extension Center.

California red scale
California red scale
(Photo by Lyle Buss, University of Florida)

“In the last weeks, we have had enough degree days accumulated for the crawlers to complete development and hatch,” said Gautam in mid-July. “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 who 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 continues, 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.

Source: AgNet West

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