Texas LRGV Cotton, Sorghum: Dryland – Drought; Fleahoppers

Cotton fleahopper adult. Photo: Texas AgriLife Extension

General Situation

For the majority of the Valley cotton and grain is coming along nicely but for those dryland farmers in Willacy County this has certainly been a rough year with the conditions brought on by the drought.

In Willacy County this year many fields were left fallow and many that were planted with cotton or sorghum did not come up at all. Some growers have started to plant sesame where they had cotton acres adjusted out. Many growers in Willacy County have cotton that is barely standing at 1 ft tall and is already blooming and will be cutting out soon.

Grain sorghum in Willacy is also standing at barely 1 to 2 feet tall with hardly any seed fill. Across the Valley it has been very dry and many crops have shown the stress symptoms of the effects of the drought with dryland farmers in Willacy County feeling the effects the most.


This week in cotton we noticed quite a bit of fleahopper activity in the McCook area and mid Valley areas.

Even though a lot of cotton has already grown out of the small pinhead square stage, for those who are trying to make 4 bales of cotton it is important to keep fleahopper populations low to none for good yield potential. Also, many planted cotton a little later and it has barely started to square, so those fields will need to monitor and treat for fleahoppers as needed.

Cotton aphid populations were light again this week throughout the valley except for areas along the river.

Red spidermite populations have been increasing and I have been finding them more consistently throughout fields. It is important to control red spidermite populations in cotton for they will stunt cotton growth and can cause its leaves to defoliate disrupting the photosynthesis of the plant which can lead to low yield.

In the Bayview area I started to see a few adult whiteflies in the middle of the canopy. Whitefly populations can be quite difficult to control if not treated early. Spiromesifen can be used as a good insecticide/miticide to control both spidermites and whiteflies. It can be used as a preventative from early to midbloom to control any whitefly populations that might be forming.

When spraying for whiteflies you will want to spray with at least 10 to 15 gallons of water per acre to get the best coverage and your product into and up underneath that canopy in order to control whiteflies. Once whiteflies start producing nymphs in the mid to lower part of the canopy it can become quite difficult to control them and they can increase in population quite rapidly especially in hot and humid conditions.

Let’s all keep an eye out for whiteflies and treat accordingly to keep the overall area populations low to none.

Bollworms. In parts of Texas we have found evidence of bollworm resistant to one or more Bt genes in our Bt cotton. Fortunately for South Texas we have not seen or experienced increased bollworm pressure like in other areas of Texas. However, if you have a Bt cotton field that has bollworm pressure this year I would like you to please contact me, (Danielle Sekula, 956-968-5581) so we may collect the larvas.

We would like to be ahead of any resistance issues and are asking for your cooperation in protecting our cotton crop.

Grain Sorghum

Saw this week some of the first grain sorghum fields with seed maturing turning color. We have been checking many sorghum fields only to find little to no sugarcane aphids (SCA) present. However this week I have noticed in the Bayview, Los Fresnos, San Benito, Rio Hondo, and Edinburg areas small SCA colonies starting to form.

While these SCA populations are very few in numbers I want growers to be mindful that we are not in the clear until we have harvested so we will be monitoring SCA populations to make sure that harvest does not turn into a sticky situation… no pun intended.

We checked several fields throughout all three counties this week for midge and did not pick up on any midge populations. I did see a few rice stinkbugs present but nothing of concern.

Corn, Sesame, and Sunflowers

Corn is maturing fast as the silks on many fields were brown or turning brown. I have found a couple of Bt corn fields with corn earworm and plan to do collections. If you have a Bt corn field and have worms present please contact me so that I may collect for further studies.

Sesame is off to a great start in McCook area as there was no pest activity of concern detected. Sunflowers are maturing as heads are starting to fill in seed and get heavy.

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