General outlook A week of 100+ F daily maximum temperatures and warm nights will give thrips development a boost over the next week. A gradual return to low 90's highs is expected by the second week of June. The current mini heat wave won't be enough to cause any mortality in thrips. Degree day accumulation for thrips this season is about two days behind last year and roughly 12 days ahead of the 30-year normal.
Population projections Generation 3 post winter adults are expected to peak in the next day or two. Generation 4 adults are currently projected to peak around June 25th. 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 soon. 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.
Merced represents the northern edge of the area where SW-5 resistance breaking strains have been found in previous seasons in the San Joaquin Valley. 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.