General situation: The main season crop is in the ground across the northern counties and canopies are filling out the beds nicely. The next 10 days is forecast to range from the low 80's to high 90's, which is ideal conditions for thrips to develop.
Resistance breaking strains of TSWV: Resistance breaking (RB) strains of the virus have been resident in Fresno county for several years. SW-5 varieties are no longer guaranteed to shrug off any early infections. After a few years of relatively simple TSWV management based on host plant resistance we're moving back into a period when a whole-system, IPM, approach will be needed to keep the virus at bay.
Thrips projections and management: We've extended the degree day model out to the end of July. Currently, the model is showing us that we're in transition from the second post-winter population to the third. Generation 3 adults will hit peak activity in the first week of June, with generation 4 adults following about three weeks later. These are the two key generations of thrips to control to prevent damage to the crop; growers who are considering investing in thrips control treatments are likely to see the biggest impact if treatments are applied any time from now through the end of June. We have had a few reports of scattered TSWV in crops and the aim now should be to stop thrips from spreading the virus from those few initial infections.