By Phillip Roberts on Mar 21, 2018
Thrips are the most consistent insect pest of cotton in Georgia and the Southeast. Near 100 percent of the cotton planted will be infested by thrips each year. For this reason preventive insecticides applied as a seed treatment and/or an in furrow application at planting are recommended. At-plant insecticides for thrips control provide a consistent yield response. Thrips infestations in cotton vary by location, planting date, and year. In some situations (high thrips infestations and/or slow seedling growth) supplemental foliar insecticides may be needed in addition to at-plant insecticides. Foliar insecticides are recommended when 2-3 thrips per plant are counted and immatures (crème colored and wingless) are present.
Thrips injury on seedling cotton is a function of thrips pressure and seedling growth. Seedlings are most susceptible to thrips feeding during early growth stages; economic damage rarely occurs once seedlings reach the 4-leaf stage and are growing rapidly. Thrips injury is more severe when seedlings are not growing rapidly (i.e. stress from cool temperatures or herbicides); rapidly growing seedlings can better tolerate thrips feeding.
A new tool, Thrips Infestation Predictor for Cotton (TIPs), is available to aid growers in thrips management decisions. Entomologists from the southeast cooperated with researchers at North Carolina State University who developed the TIPs tool. Data from Cotton Commission funded projects evaluating thrips management programs by planting date were used to aid in the creation of and to validate the tool. Additionally, county agents collected thrips infestation data from over 300 commercial fields during 2016 and 2017 as part of the TIPs tool verification effort.
The TIPs tool uses planting date, temperature, precipitation, and knowledge of when and how intense thrips infestations will be to predict risk of thrips injury to cotton. The TIPs tool can be used to identify planting dates which are at greatest risk for thrips injury. The TIPs tool will give the best predictions within 10-14 days after you use it, so use at multiple times during the planting and thrips management season would be beneficial. Dr. George Kennedy has prepared the webinar “Thrips Infestation Predictor for Cotton: An Online Tool for Informed Thrips Management”. The webinar includes an overview and how to use the TIPs tool and can be found at https://www.plantmanagementnetwork.org/edcenter/seminars/cotton/ThripsInfestationPredictor/
High risk planting dates will require more aggressive thrips management compared with low risk planting dates to achieve acceptable thrips control. Management options for high risk planting dates would include the use of in-furrow liquid insecticides such as acephate, imidacloprid, or aldicarb or the use of a neonicotinoid seed treatment plus a supplemental foliar application at the 1-leaf stage. In low thrips risk environments neonicotinoid seed treatments will generally provide acceptable control. The TIPs tool should allow proactive decisions to be made relative to thrips management. The Thrips Infestation Predictor for Cotton tool can be found at https://climate.ncsu.edu/CottonTIP.