- Author: Neil McRoberts
General outlook We're heading into to a run of slightly warmer weather which will last about a week and accelerate thrips development. With some planting still in progress and many crops at an early stage of growth we're already seeing some TSWV in the area, so we'll be keeping a close eye on the situation this season. Please contact your UCCE local adviser if you see TSWV symptoms in your crop.
Thrips and TSWV situation The projection model is showing generation 2 egg hatch peaked a few days ago and adult numbers for generation 2 will peak in the first week of May. Generation 3 adults are likely to peak right at the end of May.
Low risk situations
If you don't know of any local sources of TSWV and crops have just been planted it might be worth delaying treatment until mid June. This would be our regular recommendation in typical years. The risk is that it will allow generation 2 and 3 adults to breed and lay eggs, but if there are no local sources of TSWV the chances are that delaying thrips treatments to target generation 3 will be sufficient to delay TSWV from building up and causing severe damage.
High risk situations
If you do have local sources of TSWV, if you've planted early and are worried about early entry of TSWV to your crop, or if you do not want to take the risk of allowing generation 2 to bring TSWV into the crop, consider treatments in the first half of May. Treatments around this time will target generation 3 juveniles developing on plants and also the tail end of the generation 2 adults.