- Author: Elizabeth E Grafton-Cardwell
The San Joaquin Valley is about 80 degree days behind the 30 year average. For California red scale, we expect to see crawler activity when degree days reach 550 (with a lower developmental threshold of 53oF). Even Kern County, where the temperatures are warmest, has only accumulated 460 DD. Depending on weather, it will be about another 7-10 days before the crawlers begin to emerge in that region and even later as you move northward towards Madera. Double sticky tape around a twig next to a female scale will most accurately pinpoint crawler emergence.