California red scale management approaches could be significantly different for citrus growers this year. The cold and wet winter has had a notable impact on pest populations. Area Citrus IPM Advisor for UC Cooperative Extension, Sandipa Gautam said that the first male flight is noticeably later than in years past.
“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 either 10 to 14 days after what we see in Kern County,” Gautam explained. “This year we got a notice that they saw the first biofix [April 9], which is not just three weeks, its more than five weeks later than the warmer years. What that means is, that 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 explained. “Because unlike previous years, this year everything is going to be delayed in terms of red scale seasonal phenology.”
The year beginning with low population pressures of California red scale will also 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. Over the last decade, warm winters and hot summers have supported significant populations of the pest. “We had, I wouldn’t say an extra generation, but four and a half generations and a lot of immature populations surviving the winter as well,” said Gautam.
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