Citrus Bloom Has Ended in the San Joaquin Valley, Citrus bloom has now been called by the counties across much of the southern San Joaquin Valley, including Kern County, Tulare County, and Fresno County. With petal fall behind us, orchards are entering one of the most critical windows for pest management, early fruit development, when citrus thrips pose the greatest economic risk.
Although thrips are present year-round, but economic damage, rind scarring due to citrus thrips feedings, peak immediately after petal fall and into early summer, therefore is the most critical period to reduce economic impact. Fruit are most vulnerable from petal fall until they reach ~1.5 inches in diameter, making the next several weeks a decisive period for protecting yield and quality.
Citrus thrips are now active throughout the valleym, and monitoring must begin immediately. With warming temperatures across the San Joaquin Valley, citrus thrips populations are actively developing. Under favorable conditions, they can produce 8–12 generations per year, allowing populations to increase rapidly. If you are not monitoring now, you may already be behind. UC IPM guidelines emphasize that monitoring should begin at petal fall and continue for 6–8 weeks, with particular attention to immature stages on young fruit.
Monitor 2x per week during this critical window until fruit reaches 1.5 inches in diameter. Focus on the outside canopy, where thrips populations are typically highest. Inspect young fruit under the sepals, the primary feeding site and differentiate between flower and citrus thrips, especially early, when flower thrips still may be present. Look for thrips at the base of newly developed fruit.
This UC IPM video provides a quick, practical walkthrough on: sampling young fruit; identifying immature thrips, evaluating natural enemies, making informed treatment decisions
For management, timing is everything!! Few points to consider
- Base decisions on monitoring (Not Calendar Sprays): UC IPM strongly recommends field sampling as the foundation for treatment decisions.
- Treat only when thrips are present on young fruit. Thresholds vary by variety and market tolerance. Delayed detection reduces the window for effective control, target on protecting young fruit.
- Use selective materials: favor softer chemistries that preserve natural enemies. Predatory mites contribute to thrips control and Aphytis and other natural enemies are present. Thrips are outer canopy pest, ensure spray coverage targets the fruiting zone.
Resources:
UC Pest Management Guidelines – Detailed information on the pest, monitoring, and management choices
Citrus thrips monitoring in citrus orchards: video showing monitoring technique.
Arthropod Management Tests: Pesticide trial results published over the years
Subscribe to Citrus IPM News for updates.
To learn more about thrips, management options, and best management practices, attend “Citrus Thrips Field Day at Lindcove” on April 7. Registration is encouraged.