Your Best Thrips Management Plan Starts Before You Plant (Reisig, Huseth)
According to Dr. Edmisten and Collins, planting conditions might improve for safe planting around May 3. With planters rolling soon, we urge growers to think about thrips management now.
The best source of information for thrips activity is the Thrips Infestation Predictor. This online tool forecasts risk for thrips damage. Based on planting date, it can help growers know where to aggressively use insecticide and where to hold back, as well as where they might want to start scouting first on the farm. Growers should check this tool now to get a feeling for what infestation risk might look like for a given location and planting date. Also, since it’s based on local weather conditions, the tool’s accuracy improves closer to planting. So growers should check it just prior to planting, as well as after planting.
We also want to demonstrate why it’s so important for growers to check the tool for their farm. Here is the risk forecast for planting cotton May 2 near Edenton:This forecast looks nearly identical for a location we ran near Rocky Mount and another location we ran near Albemarle (also May 2 planting date and not shown because it looks so similar).
Here is a forecast for a location that we ran for planting cotton May 2 near Red Springs:These the predictions for these locations are very different. Cotton planted in early May near Edenton, Rocky Mount, and Albemarle is at less risk for thrips injury than cotton planted in the middle or end of May. In contrast, cotton planted in early May near Red Springs is at greater risk for thrips injury than cotton planted in the middle or end of May.
Growers planting in higher-risk conditions may want to consider an in-furrow insecticide overtop their seed treatment. In contrast growers planting in lower-risk conditions should probably just plant using a seed treatment alone. In addition to driving resistance and hurting the wallet, unneeded insecticides can sometimes cause other problems later in the season like aphids and spider mites. All growers should scout fields and be prepared to spray based on established thresholds (two immatures per seedling). We suggest scouting the fields at highest risk first. Note that insecticide sprays for thrips typically work best when you can peel back the cotyledon and see the first true leaf poking out. After several true leaves have expanded, thrips sprays have diminishing returns. This article provides a good overview of how seed treatments, environmental conditions, and thrips populations interact in relation to efficacy.