Texas LRGV Crops: Premature Senescence; Whiteflies

    White flies on cotton leaf.

    It’s amazing how things can change so quickly from one week to the next. The Valley accumulated quite a bit of rainfall last week with most areas receiving anywhere from 7 to about 14 inches of rain in the course of 3 days.

    Temperatures still remain very hot in the high 90s, low 100s during the day and in the upper 70s at night with humidity reaching 90% most days. This weather is perfect to brew up pest problems in the upcoming weeks.


    This week in cotton was certainly very noticeable to see the last of the June drop as many fields exhibited symptoms.

    Majority of the Valley’s cotton crop was shedding its small bolls and squares as we grow closer to the home stretch. Some of the Mid Valley cotton fields received too much rain that remained in the field for several days causing rot to begin while others benefited from the rains.

    In some fields we are seeing premature senescence caused by insufficient potassium in plant tissue. The condition makes cotton leaves susceptible to secondary pathogens such as alternaria, etc. The leaves will initially turn yellow in color and then rapidly change to red/orange/bronze as plant health declines. Premature senescence often occurs when dry conditions during the boll growing stage are followed by rainy cloudy days and plants have a decent boll load. Pest activity this week was very low if any at all.

    Main pest on the scene this week – adult whiteflies which could be found in just about every field in very low populations throughout all 3 counties. However with the increase in humidity will be interesting to see how quickly populations increase. Let’s control them as soon as we’re able to get back into the fields. My students picked up on a couple of tarnished plant bugs and we also saw a few verde bugs in the cotton. Majority of the cotton fields we looked at overall were pretty clean for now and we are beginning to see more open bolls in the fields as well.

    Grain Sorghum

    The majority of the Valley grain sorghum has already been harvested. For those that got rained out last week and were not able to harvest we were greeted by an influx of sugarcane aphids this week. Basically, if you have any sorghum still needing to be harvested you are probably going to want to add 0.5oz Sulfoxaflor with your glyphosate to clean up sugarcane aphid populations prior to harvest. Timely harvest prevents most growers from dealing with sugarcane aphids. But rain delays and muddy fields can produce a dramatic increase with not time to spray.

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