May 25 Update
Weather outlook: After further atypical cool, showery weather over the last week or so, the forecast for the next ten days shows a more settled period of dry weather with partial cloud cover and daytime highs increasing towards the mid 90'sF. Thrips population development can be expected to be steady over this period.
Thrips population timings: In our last update on 4/16 we projected Generation 3 adults to peak on May29th and Generation 4 to peak on June 24th. The period of cool weather has slowed development further, delaying the projected generation times by 2-3 days. The projected peak date for Generation 3 is now June 3rd, with Generation 4 now projected to peak on June 25th. We are still not hearing reports of any TSWV in the area, and together with the delay in thrips development, the overall risk level remains low. Remember that we did find SW-5 resistance breaking strains of TSWV to the north in Fresno Co. earlier in the season, so be aware that SW-5 varieties may be vulnerable to attack this season. Depending on crop development stage we recommend targeting Generation 4 for any intended thrips treatments if they have not already been made. Later planted crops might still be at early, vulnerable growth stages as Generation 4 emerges; stay on top of the situation and check in with your UCCE adviser to find out if TSWV is being reported as the season progresses.