Texas LRGV: Aphids Active, Be Aware of Volunteer Cotton in Replanted Fields

Aphids on cotton leaf.

General Situation

This week we had temperatures in the low 90s during the day and 70s at night for the LRGV. Very windy majority of the week with wind gusts recorded up to 38mph on Wednesday making it difficult to scout and get field work done. Saw many growers applying fertilizer and cultivating this week, as others were irrigating.

Cotton

This week many growers treated their cotton fields for cotton aphids as some fields did have populations increase rapidly and had heavy infestations on the growing point along the stem. Remember action threshold for treating aphids in cotton is 40-70 per leaf and it is recommended that you sample about 60 leaves per field to get an average of aphids per leaf to make your assessment.

You also want to make note of any predators you encounter in the fields feeding on cotton aphids. Select insecticide treatments that have minimal impact on predators and good efficacy on the target pest or pests.

I saw one adult cotton fleahopper around the Monte Alto area, but other than that cotton across the LRGV is clean from fleahoppers so far and I am not finding any fleahopper feeding damage or blasted squares.

Spotted a little bit of red spidermites this week as well and hopefully they will get washed off with rain soon.

We are seeing some failed acres of cotton as conditions remain dry across majority of the Valley. As we replant other crops later in the season behind failed acres, growers will want to make sure to control volunteer cotton as much as they can possible. Volunteer cotton plants can be very challenging to manage in other crops such as corn, sorghum, soybeans, or wheat, depending on the herbicide tolerant genes they contain.

Volunteer cotton plants can be quite problematic because they can serve as a host for the boll weevil (Anthonomus grandis L.) within the grain crops and negatively influence the Texas Boll Weevil Eradication Program (TBWEP) and create added expenses in the eradication program. Here is a pdf publication: Managing Volunteer Cotton in Grain Crops (Corn, Sorghum, Soybean, and Wheat), from the Texas A&M AgriLife Extension Service.

Grain Sorghum

Many sorghum fields being irrigated this week. We do have some failed sorghum acres in our dryland acreage. Seeing very low sugarcane aphid populations in sorghum along the river (a handful in a couple of fields).

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I saw many sugarcane aphids infesting Johnson grass in a field in the San Benito area and a couple of SCA nymphs in Lyford in one sorghum field I came across. However, most of the valleys commercial grain sorghum fields I checked remain clean of sugarcane aphids.

We are seeing corn leaf aphids and green bugs in the whorl being controlled by predator ladybug larvae and adults. Seeing a little fall armyworm pressure but nothing too severe that it cannot grow out of now in the whorl. It is a little early to scout for midge just yet but just for the record I did not see any activity in the blooming sorghum I checked around the Valley.

I did see in some soft dough sorghum I checked in the mid valley a few rice stink bug adults laying eggs and a couple corn earworms in the heads, but nothing that warrants treatment so far.

Corn

Corn starting to tassel around the Valley as I did pick up on corn earworm eggs and larva on the corn that is just silking along the river. Lots of fields of corn were being irrigated as dryland corn needs a good rain.

Sesame and Soybeans

Sesame in the early growth stages looking clean so far and soybeans are started to just flower across the Valley as both crops remain clean. Minimal larva feeding on the soybean’s foliage.

Sunflowers

Sunflowers in the McCook area were really starting to bloom this week as I was picking up on anywhere from 20% to 30% sunflower head moth infestation in some of the fields blooming at 30 to 50%. Sunflower head moth larva has 4–5 instars and is light brown with four cream-colored longitudinal stripes on the body and an orange-brown head capsule.

Uncontrolled larvae eventually burrow into head destroying seed–increasing susceptibility to Rhizopus head rot as they feed. From past research working with sunflowers, we found good control of sunflower head moth larvae with using Prevathon and also Besiege (a mix of Prevathon and pyrethroid).




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