General outlook A run of 100+ F daily maximum temperatures and warm nights will likely accelerate thrips development over the next week or more. A return to low 90's highs is expected in the second week of June. The current heat wave may be enough to cause some mortality in thrips, but experience suggests that any impacts on the overall population size will be limited. Degree day accumulation for thrips this season is about one day ahead of last year and roughly 10 days ahead of the 30-year normal.
Population projections Generation 3 post winter adults are expected to peak in the next day or so. Generation 4 adults are currently projected to peak around June 27th. These two generations are the first that are likely to have any appreciable level of TSWV in them, so any plans to apply insecticide specifically to control thrips and suppress TSWV should be scheduled sometime in June. If you are not seeing any signs of TSWV in your area you may want to consider delaying treatment and re-assessing the situation for generation 5.
We still have no reports of SW-5 resistance breaking strains in the Sacramento Valley so crops carrying the SW-5 resistance to TSWV should see little effect of the virus again this season. Please report any unusual virus-like symptoms to your local UCCE adviser. In addition to TSWV there are a number of other viruses that might show up in tomato. Most of these will have minimal effects on yield in processing crops, but we are always on the look out for reports of viruses to help get a complete picture of what's happening across the region.