Texas Blacklands Cotton: Insects Slowing Down, Keep Scouting Fields

    Brown stink bug on cotton boll. Photo: University of Arkansas

    GENERAL:

    Hot temperatures moved in the area over the last week with some of the highest temperatures of the year occurring last weekend through the middle of the week. Thankfully, the rain received last week helped our area corn, cotton and sorghum crop withstand these high temperatures.

    Corn grain harvest started this week while silage is still be chopped across the area. Our late planted corn should continue to be harvested for southern rust, but most of the late planted corn has reached the dent stage and the risk of economic loss from southern rust. I have seen an increase in incidence and severity in our late planted corn fields around Malone and Irene.

    Cotton across the area is growing nicely and some of our earliest planted cotton fields are approaching cut out and has a excellent fruit load. The average Node Above White Flower (NAWF) across the scouting program is 6.4, with a few fields right at 5 NAWF and some of our last planted cotton fields around 7.5 NAWF.

    Cotton insect pest issues are low now, but we need to keep an eye out for boll feeding pest such as bollworms, stink bugs, and Lygus. The area rain has created a great condition for cotton growth, and we need to keep an eye on our field’s growth rates and manage accordingly to avoid rank growth.

    COTTON:

    Thanks to last weeks rains our cotton crop has made it through this heat wave with minimal issues. Cotton pest activity has slowed down over the last week, but we need to keep an eye out for insect pest as we move into the boll filling stage. Spider mite issues were reduced thanks to the recent heavy rains and a big beneficial insect population, but if this hot dry weather pattern continues we could soon see spider mites become an issue again.

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    Bollworms are not a major issue in area cotton thanks to a couple of factors, but are being found in some non-Bt cotton that is one of my company sponsored variety trials. Now that we are getting plants with a good boll load stink bugs could soon become an issue, and should stat being scouted for in area cotton fields.

    Bollworms are not an issue in the areas cotton crop, but I am finding worms and damage is some non-Bt cotton in between Itasca and Mayfield. There was a large moth flight and egg lay around the 4th of July weekend, but the egg lay in cotton is not what I expected it to be thanks to the growth stage of other crops. When these moths were looking to lay eggs around the 4th of July there was still corn in the area with green silks and most of the areas grain sorghum was starting to flower, this attracted the moths away from the cotton.

    Stink bugs and lygus could soon become an issue in area cotton, but since our areas sorghum is still flowering it could be awhile before they really start moving into the cotton crop. Stink bugs and Lygu use their piercing sucking moth parts to pierce young maturing bolls to feed on the developing seeds. This feeding leads to stained lint, hard lock, or the lint not fluffy out when the boll opens, and their feeding damage can both transmit or cause a favorable route of entry for boll rot pathogens to enter the bolls.

    A sign that stink bugs or Lygus are feeding on cotton bolls is stained lint or wart like growths on the interior boll wall. I have seen a few stink bugs in some fields on the west side of Hill County, but I have not seen enough damage to justify treatment. The lush canopies that we have this year is very attractive and conducive for stink bug and lygus issues.

    Stink bugs should be treated when they are present and 20 percent or more of the bolls sampled have visual internal damage. The economic threshold for Lygus depends on the sampling method, after peak bloom the threshold is 4-6 Lygus per 6 row feet when using a drop cloth, or 15-20 lygus per 100 sweeps when using a sweep net.

    CORN & SORGHUM:

    Corn grain harvest started this week on some of our earliest planted corn fields, while fields are still being chopped for silage. Our late planted crop is between the late dough stage and the dent stage. Late last week (7/9) I found southern rust in corn around Irene and Malone, and over the last week I have seen an increase in the southern rust despite the temperatures being in the upper 90s and into the triple digits.

    Late planted corn fields should be scouted for southern rust and treated when at least 50 percent of the plants have 3 to 5 percent of the leaf surface of lower leaves infected with southern rust. Depending on the susceptibility of the hybrid to southern rust fungicide treatment is rarely justified after the crop reaches the dent stage.

    Sorghum across the area is flowering or past it. There are no sorghum acres in the scouting program, but we’ve had a few field visits between Bynum and Irene. Fields should be scouted for headworms, stink bugs, and sugarcane aphids.

    The moth flight that occurred over the 4th of July weekend also coincide with sorghum stating to erect from the boot and starting to pollinate, attracting the corn earworm moths to lay eggs. Sugarcane aphids are present and depending on the level of tolerane the hybrid has to sugarcane aphids there may be some fields that need to be treated to avoid economic loss.




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