How the interaction of insecticide seed treatments and early season herbicides effect thrips populations in early season cotton

Insecticide seed treatments have been applied to 99% of all cotton seed planted in Arkansas for the last several years. The last two seasons (2011 and 2012) a reduction of insecticide seed treattment efficacy on thrips has been documented and multiple post emergence insecticide applications have been needed to control thrips populations. Increased applications of pre-emerge herbicides seem to correlate with this reduction in insecticide seed treatment efficacy. Cotton growth and development has also slowed during the last two years (2011 and 2012) under optimium conditions. The objective of this research is to investigate potential interactions between pre-emerge herbicides and insecticide seed treatments with respect to thrips control and early season cotton development. Two commonly used insecticide seed treatments (Aeris, Avicta, +check) were crossed with three commonly used pre-emerge herbicides (Diuron, Cotoran, Reflex, +check) creating a 3x4 factorial. Significant differences were seen in thrips counts between the three seed treatments. However, this could not be contributed to interactions with pre-emerge herbicides. Plant growth and cotton yield were effected only by insecticide seed treatments.