In most years, control of thrips adults late in the growing season can be very challenging. This occurs largely for two reasons. First, daytime temperatures in the 70’s and low 80’s are ideal for thrips flight and dispersal. Secondly, there are fewer lettuce acres for them to disperse to. As a result, those few remaining acres of lettuce are often the only good host for thrips and are generally invaded by larger thrips populations. Also warmer temperature allows them to reproduce quicker. (Note: Alfalfa and seedling cotton are also attractive hosts that can be impacted by thrips). Keeping adult numbers suppressed in late-season lettuce can be very difficult and may require tighter spray intervals or more applications. This link will connect you to a chart of labeled insecticides and their relative efficacy against thrips species based on research conducted at the Yuma Ag Center. Note: always consult the label before applying any insecticide.
To contact John Palumbo go to: jpalumbo@ag.arizona.edu

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.