- Author: Neil McRoberts
Welcome and General Outlook
Welcome to the thrips/TSWV risk projections for pepper crops in the Yolo/Colusa region. This mini-blog is associated with the online thrips projections that can be found at http://ucanr.edu/sites/TSWVfieldriskindex/Thrips_projections_in_peppers/
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Post-winter thrips numbers are building up now. The second generation post-winter peaked on May 10 and two further generations are due by early July. TSWV incidence in pepper in Yolo/Colusa is low at the moment but the virus has been detected in one or two crops in the Colusa area. The virus multiplies quickly in infected crops so this is an important time of year to take action to manage the disease.
Projections and thrips management
The weather over the coming week is predicted to have highs in the mid 70s to the mid 80s F which means that thrips will be fully active. Generation 3 adult numbers are projected to peak on June 14, with generation 4 projected on July 7. The build up in thrips numbers over the next 2 months will be moderately fast and these generations are the ones which will really spread any TSWV that is present now. For this reason suppressing thrips now will be important to staying ahead of TSWV and avoiding economic damage. Any insecticide treatments planned for thrips control and TSWV management should be targeted at these two generations. Later treatments are likely to be much less effective. Immediate action is recommended.
Protection of tsw resistance
TSWV resistant pepper varieties rely on the tsw resistance gene. The availability of effective TSWV resistance in peppers is a huge bonus for the industry and a valuable shared resource that needs careful management. Growing tsw varieties without the benefit of insecticide protection to suppress thrips increases the chances of resistance-breaking strains of the TSWV virus developing. The larger the acerage of tsw varieties grown without insecticide protection, the greater the risk of resistance-breaking developing. For this reason, we strongly recommend that tsw varieties are treated like susceptible varieties and, if at all possible, you do not rely on the resistance alone to manage TSWV in pepper.