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 gradually increasing towards 90F. 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 May 27th and Generation 4 to peak on June 22nd. The period of cool weather has slowed development considerably, delaying the projected generation times. The projected peak date for Generation 3 is now June 19th, with Generation 4 now projected to peak as late as July 12th. We are still not hearing reports of any TSWV in the area, and together with the delay in thrips development, the overall risk level in Yolo and Colusa is low. Depending on crop development stage we recommend targeting either Generation 3 or Generation 4 for any intended thrips treatments. There are a lot of young crops at the moment and planting still in progress so although thrips development is later than typical this year there will still be crops at early, vulnerable growth stages as Generations 3 and 4 emerge; 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.