CROP AND PEST SITUATION KERRY SIDERS WEST PLAINS IPM UPDATE

In most areas, August is the prime time to make a cotton crop. And, in most situations, the crop is looking pretty good despite increased insect pressure. Here’s what the Crop Scan consultants told us in early August.

Here on the Southern High Plains of Texas, cotton ranges from just beginning to bloom with more than 6 nodes above white flower (NAWF) to past physiological cutout with 2 NAWF. I must stop and preface these comments. These are irrigated acres that we have remaining, which is only about half of what was planted.

Using our IPM scouting fields as a representation of the area cotton crop, we see that 60% of fields have reached physiological cutout (<5 NAWF) this week. For those fields, we need approximately 350 DD60 more heat units to accumulate to be safe from bollworms. With the current weather trend of +20 heat units per day, those fields which have reached cutout should be safe from bollworms around August 21. The remaining 40% of the cotton acreage has such a wide range of maturity levels that it would be difficult to be as certain of when it will be safe from worms.

I would approach these later maturing fields from this angle. We historically say our last effective bloom date is August 15. This is a date in which a boll can be formed, have time to mature, and contribute to yield. Therefore, if we continue with this weather pattern into September and we are accumulating 20 HU/day, we can add 17 days to this date. This would give us a target of September 1 for those late fields needing to be scouted and protected from worm issues.

The point being is that NAWF is an important gauge of maturity and can help project time needed to be safe from worms and even manage irrigation.

Currently, bollworms are just beginning to be found infesting area fields and need to be scouted, particularly those varieties with lesser than Bollgard II or no Bt technology. Lygus, stinkbug, cotton aphids, and mites should be included in those scouting procedures. Cotton aphids have been the most common insect. To date, beneficial insects such as lady beetles and lacewing have kept up and cleaned up most of the infestations. Remember, cotton aphids thrive in skippy cotton and late nitrogen. Late nitrogen can also delay cotton maturity.

For more information on managing cotton insects in Texas, download the AgriLife Extension manual on insect control. My priority list for the rest of August and going into September: • Keep a close watch on cotton bollworms, larva pests in general, cotton aphids, and Lygus. Scout, apply at economic threshold, and act on good information.

• Continue with late season weed control: residual herbicide, cultivate, hoe, whatever it takes to keep the pigweed from going to seed. It is a numbers game.

• Do the best you can to keep up with water demands of the cotton. Remember, we make cotton in August.