Texas West Plains Cotton: Pests Mostly Quiet, Lygus on the Rise

    Mature cotton bolls. Photo: Texas AgriLife Extension

    Cotton has made good progress the last several days with generally 90-degree temperatures and mostly clear skies. I have received several calls about heat unit accumulation this year. I cannot calculate for every location but here are some stats on heat units (HU) for Levelland based on my National Weather Service observations that I submit each morning.

    From May 20 until August 26, we have accumulated 1602 HU (DD 60). In June we averaged 17.4 HU per day, July we averaged 16.5 HU, and here in August we have averaged only 16 HU per day. Based on historical average daily temperatures from this point on we should accumulate an additional 350 HU. This will give us a projected total of 1952 HU for the season. This is about 200 HU less than our historical average of 2160 HU.

    As I have stated before “we make cotton in August.” We have continued to be blessed with rains this month. There is a slight chance for rain at the end of weekend and latter part of next week. Temperatures have already begun to moderate, and we are losing day length as well. I mention this because of my nervousness as we go into September.

    Pray for open sunny weather with an occasional gentle rain. We all know though that we can have some weather events which can undo all the hard work we have applied to our crops. Now I do not mean a hail-out, I’m talking regrowth, and delayed maturity. So, this said, and to my point… be careful irrigating into September.

    Cotton insects generally have decreased across most area fields. I am not seeing the numbers of cotton aphids I did a few weeks ago. Most of these were cleaned up by ladybird beetles, green lacewings, and parasitic wasps. Cotton bollworms and an occasional armyworm species can be found in cotton but little damage. The grain in the area has taken much pressure off from worms.

    The late and/or growthy non-Bt cotton fields with three and more nodes above white flower, scattered throughout both Hockley, Cochran, and Lamb counties will need to be checked for another 10-15 days. Lygus have become more common this week, so watch for them.

    Cotton fields which reached physiological cut-out (5 nodes above white flower) before August 10 should have accumulated 400 heat units by September 4 and will be safe from most insects other than cotton aphids. I plan on continuing to watch scouting program fields through end of September.

    AgFax Weed Solutions

    Grain Sorghum is all over the board in terms of plant development and insect pests. I would say that if you have not checked your fields lately then now is the time, especially flowering milo. Sugarcane aphids (SCA) are present in ~50% of fields with ~10% needing treatment. Following the SCA activity in importance is headworms.

    Generally, I can find a small worm on 1 out of 10 heads when it is flowering. Post flowering grain however, that number has jumped to 1-3 worms per head. Call me if you have questions.

    Corn is mostly quiet with some small colonies of spider mites being found, but with beneficial insects holding them in check. Earworm feeding continues to be limited to ear tips. Good many fields are early dent or later.

    Peanuts are maturing fast at this point. The peanut crop is uniform in terms of pod maturity and harvest may come sooner than on may anticipate. Conditions for leaf spot have lessened somewhat but could return when weather changes again.

    Wheat planting preparations are being made. If you will be planting wheat, soon be sure to destroy volunteer wheat which may have come up from recent rains as it can host insect pest and disease which can infest new crop. Allow at least a two-week window from point of destruction of volunteer to emergence of planted crop.

    For those who may have missed this publication from Dr. Jourdan Bell on Wheat Picks here you go.

    My Priority List for September

    1. Wrap up irrigation on pivots ASAP, and drip over the next several days.
    2. Make notes of which fields you notice cotton wilt symptoms, so that you might consider
      this in your selection of cotton varieties for next year.
    3. Take soil samples for cotton root-knot nematodes. Much easier while we have soil moisture. This will help in determining degree of management for next year.
    4. Make good notes of problem weed fields so that you can design an effective plan for next year.

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