Mud, Aphids, and Armyworms

Howdy,

  This week got muddy pretty quickly, and I didn't spend the amount of time I would have liked in the field. I saw some thrips in cotton, but not high enough numbers to treat. Threshold for thrips is 1 per true leaf until the cotton plant has more than 5 true leaves. There are also cotton aphids around. I haven't seen enough to justify treatment yet, but the agent in the valley (Danielle Sekula) has been getting incredibly high cotton aphid numbers in her area. I have been seeing cotton aphids in our fields as well, but not at the extreme numbers Dani has. Keep in mind that there would need to be 50 aphids per leaf before treatment would be warranted for aphids in cotton.

  The sorghum is looking good in Matagorda county. I did find sugarcane aphids on the edges of fields in Johnsongrass consistently in all three counties, but I have not seen them in the sorghum yet. If you do see them moving into sorghum, please give me a call and let me know so I can update our status on the national sugarcane aphid map. Danielle has reported sugarcane aphid numbers in the valley, and some of the growers have treated with Sivanto or Transform and gotten good control. Dr. Bowling mentioned that he has seen high numbers of corn leaf aphids in sorghum this year as well, from the Rio Grande Valley and into San Patricio county. It's been creating some confusion as to the differences between corn leaf aphids and sugarcane aphids. His photo of the corn leaf aphid is below. For more information on the aphid species, check out Dr. Bowling's website.

Photo: Jason Thomas

Photo: Kate Harrell

  Below are some photos of armyworm damage I found near Palacios. This damage was not near treatable levels. Armyworms and earworms are whorl feeders in this stage, and the "shotgun blast" pattern of feeding is typical. They chew through the leaves while they are still curled up in the whorl, which results in the "shotgun" type holes. Insecticide application may be justified if larval feeding reduces leaf area by more than 30 percent or is damaging the developing grain head or growing point within the whorl. Otherwise, it is better not to treat, especially given the potential to flare aphids with a pyrethroid treatment.

Typical Armyworm damage
Photo: Kate Harrell

Typical Armyworm damage
Photo: Kate Harrell

Armyworm
Photo: Kate Harrell

  Let me know if you have any questions or concerns, and please let me know if you see sugarcane aphids in sorghum. Have a good weekend, and good luck to all the 4Hers competing at the Wharton County Youth Fair in the coming weeks.

Sincerely,

Kate