CRS degree day updates 2026
Biofix: March 1, 2026.
As of April 24, 2026, Fresno County has accumulated approximately 639 degree days (base 53°F) since the March 1 biofix for California red scale. This indicates that first-generation crawlers have begun emerging and are expected to continue, as the population has passed the ~550 DD threshold for crawler emergence. This is a key management period because crawlers are the most susceptible stage for control, and treatment decisions should be based on confirmed field observations such as white caps and crawler presence on tape traps rather than degree days alone. The second male flight is expected around 1100 DD (late May to early June), followed by second-generation crawler emergence near 1650 DD (mid-summer). Orchards using mating disruption should ensure dispensers are installed before the second flight (~May 25) to ensure effective population suppression. Management should follow UC IPM guidelines, with field-by-field monitoring due to variability in microclimate and pest development across Fresno County orchards.
For more information on DD on previous seasons and 30-year average data, click here.
Individual field conditions may vary. Monitor Individual fields. For treatment recommendations UCIPM Guidelines for citrus