General situation After a slow, late start to the season, summer has finally arrived and is staying. Fresno will see temperatures building over the next few days and settling into an extended period with 100+ highs, with several highs in excess of 110 predicted. All that heat will really accelerate thrips development and increase their activity.
Thrips generations and TSWV We have extended the population projection out to September 1. Generation 5 adults should peak around July 11, with generation 6 following around July 29. Thrips numbers have been low across much Central Valley until now, but TSWV is relatively easy to find in most areas, albeit at relatively low incidence. Resistance-breaking strains of TSWV are now ubiquitous in the San Joaquin Valley, so varieties with the SW-5 gene will need protection in situations where thrips pressure is high.
In normal seasons most of the crop would be far enough along that our main concern would be generation 4, but there are quite a few late-planted fields and generations 5 and 6 could bring in TSWV before these crops are big enough to shrug off virus strikes. Late-planted crops might require additional protection this year, particularly in locations with a history of TSWV damage.