Late Start for California Red Scale

Josh McGillCalifornia Corner, Pests

This year’s first male flight of California red scale is noticeably later than in prior years, according to Sandipa Gautam, area citrus integrated pest management advisor for University of California Cooperative Extension.

California red scale
(Photo courtesy of University of Arizona Cooperative Extension)

The cold and wet winter has had a notable impact on pest populations. “Usually, March 1 is tentatively the time when we see the first male flight in Kern County. In Tulare, Fresno and Madera counties, things happen 10 to 14 days after what we see in Kern County,” Gautam said. “This year we got a notice that they saw the first biofix (April 9), which is more than five weeks later than the warmer years. What that means is that the first generation which would usually come by the first week of May is going to come later this year.”

Infestation generally begins with the overwintering population from the previous season. However, the overwintering immature population has largely died off this year from colder temperatures. The season is beginning with mostly adult populations as a result. Populations are also going to be more synchronized for the first few generations. With the first biofix only recently being seen in Kern County, growers will want to update their management approaches accordingly.

“Especially the growers who were planning on spraying the fields early in May, targeting that first generation, they might want to go and walk the fields and see what’s happening with the population,” Gautam said. “Because unlike previous years, this year everything is going to be delayed in terms of red scale seasonal phenology.”

Low population pressures of California red scale will impact the remainder of the season. The accumulation of degree days has been slower than in the past few years. If those trends continue, it could mean that growers may only be dealing with four generations this season.

Source: AgNet West