By Dominic Reisig
North Carolina State University
Most everyone knows some type of preplant control measure is needed for thrips, whether it’s an insecticidal seed treatment or an in-furrow insecticide. But should you use a seed treatment and an in-furrow? What about a foliar spray? The thrips forecasting tool can help with those decisions.
Thrips injury is a function of weather-driven seedling growth and thrips pressure. The thrips forecasting tool uses planting date, temperature, precipitation, and knowledge of when thrips pressure will occur and how severe it will be to predict when cotton is at risk.
Use this tool to save time and money by focusing your most intensive thrips management efforts on cotton that will be planted at a time most at risk for thrips. It’s also a good idea to scout these areas more intensively as well.
A thrips spray based on injury is typically too late to prevent crop damage. The presence of immature thrips indicates at-plant insecticides are running their course and a spray may be needed. Cotton is most sensitive to thrips damage when the first true leaf appears between the cotyledons. Although foliar sprays at later stages (two to three true leaves) may occasionally benefit yields, targeting sprays at the first true leaf has proved to be the most effective timing.
When Should I Use This Tool?
The thrips forecasting tool gives the best predictions within 10-14 days after the date you use it since it is based on weather forecasts. Therefore, use the tool two weeks before planting to make preplant decisions and also check it a few days before planting. Use the tool every week after planting to track damage potential until cotton reaches the four-leaf stage.
Go to http://www.plantmanagementnetwork.org/ and click “Focus on Cotton” to view a Web-based presentation about the tool. It includes an overview of how to use it for individual locations in North Carolina and the Southeast Cotton Belt.
Any forecast will have some uncertainty. However, this tool is based on many years of data from across the Southeast Cotton Belt and has been validated several years since. We are confident that when used as instructed, it will accurately forecast thrips risk to cotton.
Go to http://climate.ncsu.edu/cottonthripsrisk/ to access this tool.