Citrus growers in the southern San Joaquin Valley are entering a critical pest management period following the end of citrus bloom, according to an April 1 announcement. Counties including Kern, Tulare, and Fresno have reported that orchards are now especially vulnerable to citrus thrips, which pose significant economic risks during early fruit development.
This period is important for growers because citrus thrips can cause rind scarring on young fruit, impacting both yield and quality. The next several weeks are considered decisive for protecting crops as fruit remain most susceptible from petal fall until they reach about 1.5 inches in diameter.
The University of California Agriculture and Natural Resources (UC ANR) said that with warming temperatures across the valley, citrus thrips populations are actively developing and can produce between eight and twelve generations per year under favorable conditions. “If you are not monitoring now, you may already be behind,” UC ANR said in its statement. UC Integrated Pest Management (IPM) guidelines recommend beginning monitoring at petal fall and continuing for six to eight weeks, focusing on immature stages found on young fruit.
Growers are advised to monitor twice weekly during this window until fruit reach 1.5 inches in diameter. Monitoring should focus on the outside canopy where populations tend to be highest, inspecting under sepals at the base of new fruit while distinguishing between flower and citrus thrips.
UC ANR also encourages field sampling rather than calendar-based sprays when making treatment decisions: “Base decisions on monitoring (Not Calendar Sprays): UC IPM strongly recommends field sampling as the foundation for treatment decisions.” Selective materials that preserve natural enemies such as predatory mites are recommended since these contribute to pest control.
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A Citrus Thrips Field Day will take place at Lindcove on April 7 for those seeking further information about best management practices.