This is a re-run of an article posted last year. The timing is right as many fields are at or approaching cutout. Counting the number of nodes above first-position white flowers (NAWF) is a well-recognized way to monitor the maturity of your cotton crop. Cutout is defined by having an average of 5 nodes above first-position white flowers. If you record the date of cutout, you can start counting down the days until insecticide applications for some insect pests can be terminated.
The blooms present at cutout (NAWF5) represent that last effective bolls that will contribute to yield in a substantial way. Thus, you only need to protect these bolls from plant bugs, stink bugs, and caterpillar pests until they are relatively safe from attack. You will sometimes see in well-watered situations that the crop may stay at or near NAWF5 for a couple of weeks. If this is true in your field, record the latest date of NAWF5 and start the clock from there. Below are some general guidelines for terminating insecticide applications based on NAWF5 rules and typical temperatures.
- Tarnished plant bugs – controls can typically be terminated about 14 days after reaching NAWF5 (or NAWF5 + 250 DD60s)
- Clouded plant bugs, stink bugs and bollworms – terminate insecticide applications at about 18-21 days after hitting NAWF5 (or NAWF5 + 350 DD60s)
- Spider mites – terminate applications at about NAWF5 + 600 DD60s. However, fields that are essentially free of spider mites at NAWF5 + 350 DD60s are at low risk to substantial yield loss afterwards.
You are just guessing at the maturity of your crop if you are not keeping NAWF records. All this assumes that insect and mite pests have been well managed up to the time of termination. You can’t walk away from a raging infestation of bollworms or stink bugs just because you hit the magic date. For more information about NAWF rules and calculating DD60s, please refer to http://www.utcrops.com/cotton/cotton_insects/NAWF.htm.