What is in this article?:
- Is your cotton field at high risk or low risk for thrips?
- Some research to back it all up
- Georgia cotton planted in April or early May in a conventional tillage system is “High Risk” for thrips. Cotton planted after mid-May and/or in a reduced tillage system is “Low Risk” for thrips.
Some research to back it all up
Data was summarized from small plot trials conducted by UGA which included a NST with and without a foliar insecticide spray at the 1-leaf stage. In total 23 trials conducted from 2001 to 2013 were included in the data summary. Individual trials were assembled into “Risk Groups” based on planting date and tillage practice. Trials which were planted prior to May 10 in a conventional tillage system were placed in the high-thrips risk group. Whereas trials planted after May 10 and/or in a reduced tillage system were placed in the low-thrips risk group. Trial yields from the NST alone and the NST+foliar 1-leaf treatment were compared in each risk group using a paired t-test.
Sixteen trials were placed in the high-thrips risk group and seven trials were placed in the low-thrips risk group. Yields were numerically increased in 22 of 23 trials with an average yield increase of 251 lbs. lint per acre when a NST was used compared with no insecticide plots. Yield responses tended to be greater in trials conducted in high risk environments. On average yields were 308 and 121 lbs. lint/acre higher when compared with no insecticide plots in high and low risk environments respectively. This consistent yield response to NSTs is why most growers use preventive insecticides at planting for thrips control.
Foliar insecticide (generally acephate at 0.18 lb ai/acre) was applied at the 1-leaf stage. On average the foliar insecticide was applied at 16 DAP with a range of 13-20 DAP. Yields were not statistically different (prob (t) = 0.6043) for NSTs with and without a supplemental foliar spray in the low risk environment, 1335 and 1348 lbs. lint/acre respectively. Whereas, the NST+foliar 1-leaf treatment had significantly (prob (t) = 0.0122) higher yields compared with the NST alone in the high risk environment, 1526 and 1457 lbs. lint/acre respectively.