Terminating Insecticides Applications in Cotton

In many areas across the state, acres are quickly approaching the point of insecticide termination. All insect termination suggestions are in terms of NAWF5 plus x heat units.  NAWF5 refers to node above white flower 5 or cutout. This is the point in the growing season that the terminal growth slows and the majority of plants have a first position white flower five nodes down from the unfurled terminal leaf.  The accumulation of heat units is based on DD60’s which will vary depending on your location within the state. Using the Mississippi State University Delta Agricultural Weather Center , you can generate the DD60’s for your area.  For example, in order to terminate for tarnished plant bug/ bollworms we need to reach NAWF5 plus 350 plus heat unit. Let’s say that with current temperatures, 20 heat units are generated each day. Therefore, it would take roughly 18 days (350 heat units divided by 20 heat units per day equals 17.5) after NAWF5/cutout to reach the desired termination timing. These termination timings are based on research that target the last point in the growth and development of the plant that will produce a boll that contributes to yield. The purpose of the additional heat units after NAWF5/cutout is to allow those bolls to develop enough that there is a low probability of sustaining economic damage from insects.  Heat unit accumulation has not always been the most widely used practice. Therefore, based on preliminary data from graduate student research, NAWF5 plus 350 heat units for tarnished plant bug, bollworm, or spider mite termination is roughly NAWF2.  Below are the recommended termination timings for common cotton insect pest. This information can also be found on page 19 of the 2023 Insect Control Guide for Agronomic Crops.

Insecticide Termination Timings:

• Tarnished plant bugs and bollworms: NAWF 5 + 350 Heat Units
• Spider Mites: NAWF 5 + 350 Heat Units
• Soybean looper: NAWF 5 + 350-400 Heat Units
• Stinkbugs: NAWF 5 + 450 Heat Units
• Fall Armyworms: NAWF 5 + 500-550 Heat Units