Texas LRGV: Aphids Skyrocket in Cotton, Keep Watch for Sugarcane Aphids in Sorghum

Aphids on cotton leaf.

General Situation

Over the weekend many growers received some much-needed rain around the LRGV. Majority of Valley got anywhere from 1 inch to 2.5 inches with a handful of places getting 3 inches, then were a few areas that only got 5-9 tenths of an inch. All the crops really needed the rain and took off in growth this week after.

Cotton

This week many growers were at it again treating for cotton aphids as populations soared rapidly after the rains received over the weekend. Prior to the rains many growers had low to moderate aphid populations with predators keeping them in check.

However, with the added moisture, increase in temperature and humidity that scenario changed quickly as the weather was perfect for aphids to reproduce quickly causing infestation levels that could not be controlled fast enough by natural predators (ladybugs & scymnus) and required treatment.

On the upside we are not seeing any fleahoppers present at this time, nor are we seeing their feeding damage or lack thereof. Along the river though we are still seeing heavy thrips pressure. If you have cotton in the early growth stages (cotyledon – 4 true leaf) please check your cotton for thrips pressure as it might very well need treatment based on what I saw scouting along the river this week.

Generally, after 5 true leaves when the plant begins to square treatment of thrips is hardly justified but numbers were so incredibly high along the river that thrips need to be controlled to prevent stunted plant growth. Thrips species I am seeing so far are tobacco and western flower thrips.

Grain Sorghum

This week we definitely saw the presence of sugarcane aphids in sorghum increase. Majority of the fields we scouted we were only finding a handful of SCA on the undersides of leaves. However, we did come across a few fields that were at threshold for SCA pressure and I recommended treatment.

What I can tell you is that right now majority of Valley’s sorghum fields are way below threshold but need to be checked periodically (every 4 days) since aphids can reproduce so rapidly and management decisions need to be made in advanced.

When scouting your sorghum try to grab leaves from the middle of the canopy randomly in about 3 to 4 locations in your field, looking at the undersides of the leaf along the midvein as that is where you will find SCA feeding. Remember that if the field average of SCA is 50-125 aphids or more per leaf, then it is recommended that you apply an insecticide within 4 days of finding this infestation level, much sooner if you are averaging 100 SCA per leaf or more.

AgFax Weed Solutions


Now we are seeing a lot of corn leaf aphids in the sorghum as well, but these aphids are of little concern and tend to hang out feeding in the whorl, these are Not sugarcane aphids. Sugarcane aphids are creamy light-yellow color, like mucus. Corn leaf aphids are greenish/blue with dark black cornicles.

Also, we are finding Yellow sugarcane aphids at the very two bottom leaves of the sorghum plants, these aphids are a bright yellow and very hairy and also are Not SCA.

If you do end up spraying try to use drops on your booms as I am finding the SCA mid to lower canopy along with yellow-sugarcane aphids at the bottom and will be hard to penetrate and get chemical down in there if not using the drops, also make sure to use plenty of water to receive good coverage.

Finding a few headworms along with rice stinkbug adults laying eggs already in flowering and soft dough sorghum; not alarming numbers yet but they are certainly entering the fields so whatever you spray be mindful of this.

Corn, Sesame and Soybeans

All three of these crops are looking very clean of pests. Corn across the Valley is tasseling and silking. While sesame and soybeans are starting to flower.




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