General Situation  After the wet winter and extended cool spring, the annual summer weather pattern finally seems to have established itself. Temperatures for the next 10 days will see daily maximum values in the mid to high 80'sF, reaching the mid 90's by the first few days of June.  Planting has been happening rapidly over the last 2-3 weeks and crops will pull away quickly with settled warm conditions.

Thrips and TSWV We have had a few sporadic thrips detections but no TSWV so far in Fresno county.  There's a wide range of crop growth stages in the main planting areas, from stuff that has only gone in the ground in the last 7-10 days, up to crops that are bushing out well, and flowering is underway.  The low thrips numbers and lack of TSWV is all good, but we are concerned that the late planting times will mean that the pre-flowiering high risk period for TSWV will be extended this year.  We are predicting that Generation 3 adults will peak around June 3 and Generation 4 adults will peak around June 25.  Given the slow start and low leves of TSWV so far, unless there is a local source of TSWV, Generation 4 seems the more likely source for any significant chance for TSWV to spread around, and the more likely to pay off in terms of investment in thrips control.  Contact your local UCCE adviser if you want to discuss options specific to your situation.

Resistance breaking TSWV Remember reistance breaking strains of TSWV are now widespread in the San Joaquin Valley, so varieties carrying the SW-5 resistance won't necessarily stand up on their own without thrips management if there are local sources of TSWV.  At locations with a history of TSWV it's probably better to treat SW-5 varieties the same way as varieties without the resistance gene.

General situation: The main season crop is in the ground across the northern counties and canopies are filling out the beds nicely.  The next 10 days is forecast to range from the low 80's to high 90's, which is ideal conditions for thrips to develop.

Resistance breaking strains of TSWV:  Resistance breaking (RB) strains of the virus have been resident in Fresno county for several years. SW-5 varieties are no longer guaranteed to shrug off any early infections.  After a few years of relatively simple TSWV management based on host plant resistance we're moving back into a period when a whole-system, IPM, approach will be needed to keep the virus at bay.

Thrips projections and management: We've extended the degree day model out to the end of July.  Currently, the model is showing us that we're in transition from the second post-winter population to the third.  Generation 3 adults will hit peak activity in the first week of June, with generation 4 adults following about three weeks later.  These are the two key generations of thrips to control to prevent damage to the crop; growers who are considering investing in thrips control treatments are likely to see the biggest impact if treatments are applied any time from now through the end of June.  We have had a few reports of scattered TSWV in crops and the aim now should be to stop thrips from spreading the virus from those few initial infections.

General Outlook Well, here we are, the 2022 season is open for business.  Transplanting is under way (or soon will be). The first half of the winter was wet and cold, but since the turn of the year, we have seen next to no precipitation in the region.  Temperatures have been more or less normal for the time of year and all in all it has probably been a reasonably good year for thrips survival as pupae in the soil over the winter. Unless we get some serious cold wet weather to round off the spring the prospect is that thrips numbers are likely to start building quickly over the next couple of months.  The next 10 days or so will see changeable weather with a cool weekend and start to next week (with a small chance of rain showers on Saturday) giving way to a run of three or four days with temperatures in the low 90's.  Those kinds of temperatures will accelerate thrips development.

Population projections  Based on temperatures experienced at the Stratford monitoring site, the current projection is for generation 1 adults to peak around March 25, with generation 2 egg hatch peaking in mid April and generation 2 adults peaking in the first week of May.  Unless you are in an area with a history of early TSWV infections and you suspect that the virus is already present in weeds or other crops close by, the chances are that the first couple of generations of thrips will be relatively free from virus and usually do not pose a serious threat to new tomato plantings.  We've had a few reports of TSWV in lettuce in the area so be aware that there is some virus around and we might see it move into tomato early this year.  Contact your local UCCE advisor if you are concerned about your situation and wondering when/if to start treatments to suppress thrips.