Last week I reported the results of a foliar insecticide test for thrips on cotton at the WTREC (sprayed 5/18, rated 5/21). Cotton was at the 1-leaf stage at the time of application, and an at-planting insecticide or seed treatment was not used.  A follow-up application was made on 5/22 and rated 5/25.  All treatments included an adjuvant (as recommended for Radiant). Neither Acephate of Radiant provided great control after the first application, ranging from a 63-72%.  A second application improved control considerably, giving almost a 90% reduction in thrips populations regardless of treatment.  Western flower thrips are not common at this location, and thus, there was no obvious advantage to using Radiant.  The moral of the story …  two sprays may be needed to adequately control high pest populations … and a failure with acephate does not always indicate the presence of western flower thrips.  

Mean number of thrips per 5 plants at 3 days after a first and second application.

 Means not followed by a common letter are significantly different (P < 0.05).