West Texas Cotton: Insects Quiet, Some “Occasional Pests”

Current Conditions

I know it’s the same ol’ tune but one we like to hear – the insect activity is pretty much non-existent.

“Occasional Insects”

With the drought in place this year, there are some insects classified as “occasional” showing up. They are not hurting the crop overall, but there are a few locations that have been treated.

One such insect is the smartweed borer. The moth numbers of this insect can be alarming as you might kick up 40 moths with each step you take in the area of the field in which they are located. We saw this moth back in 2013 and this is what was written about it:

The adult moth is less than 1.0” across the base of the wings and triangular in shape; it resembles the European corn borer adult. In fact this moth is a relative to the European corn borer. European corn borer moths have been absent in this region for some time due to the widespread use of Bt corn.

“The host range for the smartweed borer are primarily different weeds, cocklebur, ragweed cat-tail and lamb’s quarter. But late in the season they can be found in corn, cotton, and goldenrod. The text books do not mention grain sorghum as an alternative host.”

The question remains as to whether the smartweed borer will be a pest issue in cotton. With plenty of weed hosts available, it is likely this insect will not be problematic in area crops, however, many times things change and issues develop.

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Another is the garden web worm. Got a call or two about this one a couple weeks ago. This insect’s feeding habit is to skeletonize the leaf leaving the leaf vein in tack, and translucent leaf surface. They also produce a web around their feeding area, and this webbing will have black frass scattered throughout. Typically, these worms are highest on cotton in areas that have a high population of pigweed (careless weed).

Management of these insects can be done through spot spraying around areas where the worms are on cotton or on pigweed, this will be effective and less costly than spraying the whole field.

One more insect that has shown up, especially along the Cap Rock and is associated with pasture ground is the Conchuela stink bug. These feed on squares and bolls causing fruit shed, seed damage and lint staining. Stink bugs are often clumped near field margins. There has been a few fields treated for this.

Am I concerned that these insects will cause major issues in our cotton this year? No, not overall but they do give me something different to talk about rather than always saying “I know it’s the same ol’ tune but one we like to hear – the insect activity is pretty much non-existent”.

First Bloom and Nodes Above White Flower (NAWF)

As the plant flowers, measurement of the height/node ratio becomes less important, and nodes-above-white-flower (NAWF) measurement becomes more important as a plant monitoring tool.

NAWF at first bloom provides one of the most accurate mid season predictors of yield. The cotton plant needs to be growing rapidly at first bloom. Vigorous cotton plants have more momentum or “horsepower” to take the plant further into the the fruiting cycle before cutout. The method to measure this horsepower is NAWF.

NAWF count starts at the node with the upper most first position white flower. A first position white flower is the flower on the first fruiting position closest to the main stem. This node is counted as 0 and nodes are counted to the top of the plant stopping with the node which has the terminal main stem leaf as large or larger than a quarter.

As the plant develops, flowering will slowly advance toward the plant terminal. The speed of the advance varies, but should be approximately one NAWF per week. As flowering progresses up the plant, terminal growth will also progress, but at a slower rate. The objective of insuring good yields is to keep the plant in a fruiting mode and to slow the advance of the white flower toward the terminal of the plant by adding terminal nodes as the white flower advances up the plant.

At early bloom, NAWF on most full season picker varieties should range between 8 and 12 and on short season stripper varieties, should equal 7 to 10 nodes. As boll loading progresses, NAWF declines. Rate of decline is important; a rapid decline indicates the plant is experiencing severe stress.

If NAWF was high at first bloom, this decline could be due to boll loading and high demand for nutrients and water. When NAWF does not decline after first bloom, or it increases, the boll load is not developing sufficiently to hold the plant back. Boll loss could have been from lack of adequate moisture, cloudy days, lack of enough heat units, or insect damage.

When NAWF reaches 5, fruiting growth will start to overpower vegetative growth and this is defined as physiological cutout.


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