Editor’s Note: Please excuse the mistakes, and see the following for a corrections to last week’s newsletter:
- “Square and boll retention could be affected by cloudy weather”: cloudy skies only affect square retention, not boll retention.
- “Sample 100 squares, 20 at 4 sites”: this was a typo, should be 5 sites to make a total of 100 squares.
- I didn’t specify, the 30% square damage is for pre-bloom cotton. During bloom it is 5-6% with 8-12 worms over .25 inches present.
We had a wet holiday here in Hill County with some areas getting over 2 inches on the 4th of July. Corn is drying down quickly and milo is nearing hard dough. Cotton is growing well but key pests are on the radar.
Cotton ranges from matchhead square to middle of bloom. Some producers are applying plant growth regulators on their cotton this week to slow the rapid growth caused by regular rains for the past few weeks. Products like Pix (mepiquat chloride) are used to switch cotton from vegetative to reproductive growth, basically telling the plant to divert more energy to lint and seed production instead of stems and leaves.
Bollworm egg lay continues and several fields are seeing high levels of larvae. One to three day old bollworms have been found dead after feeding on squares in many fields, but surviving worms continue to cause damage. Once larvae reach above about 1⁄4” in length, we can assume that the Bt toxins will not kill it. Fields should be scouted at least every 3-5 days at this time. Sample 100 squares, 20 at 4 sites, across the field (more in larger fields): if 30% of those squares have feeding damage from worms, it’s time to consider treating. When sampling squares for damage, don’t choose squares that are already flared, or dropped to the ground. That is old damage and will throw your percentages off.
Some brown stinkbugs have been seen lurking about the cotton plants, but we mainly become concerned with them after bolls form. Fleahoppers are no longer a concern for most fields. Most cotton in the county isn’t stressed and square retention is high, even though we have had quite a few cloudy days during bloom.