Last week, Hale and Swisher County experienced some damaging weather. The amount of rainfall received ranged from 0.12” to a little over 2”. Most of the heavier rainfall came down hard and fast, and was accompanied by hail. Hail can beat the cotton seedlings leaves to shreds or completely off. The seedlings can survive such a beating from wind and hail if the plant still has a healthy growing point. The plant can still be considered living if a growing point, terminal or alternate, still remains. Those growth points should be re-growing leaves and green shoots soon after the damaging event. Four to five days after a damaging event should be enough time to tell which plants have healthy growing points and which do not. These plants will be unavoidably delayed, but should have more potential than a late season replant, if there remain enough plants per acre in the field.
We received a great deal of wind along with the rain and hail last week. Some locations even had wind speeds up to 80 miles per hour. Wind alone can damage young cotton leaving sand blasted, tattered, and burned looking plants. Under the right conditions, winds can generate static electricity by lifting small soil particles and bouncing them along the soil surface. The resulting electric discharge seriously affects seedling cotton as the now electrified particles are carried past. The impact of these tiny static electrical discharges have a cumulative impact upon seedling cotton causing cell rupturing which leads to leaf curl or burn, stem damage, and in the worst cases, seedling death. Fields do not necessarily have to be ‘blowing’ for this type of damage to occur.
Sand blasting causes similar damage but wind direction can usually be determined by the resulting damage to the seedling. Plants along the edges of fields tend to catch more of the damage from wind and sandblasting, especially if they are near a road or any other area with bare ground. A plant with stalk bruising from wind damage or hail will take longer to recover. Ground cover or a rough soil surface can help to reduce the amount of damage a field takes. Wheat trash and other stubble in a field can prevent blowing dirt or any lifting of small particles. Very few fields in the area have lost large amounts of yield potential to wind damage alone.
Several producers have lost cotton fields to hail while many others will be evaluated this week. Stand counts will help greatly in determining whether or not a field will make, or if it needs to be replanted. A minimum of 27,000 fairly evenly distributed plants per acre need to have healthy growth points before the field loses profit potential. Gaps in a field that are larger than a foot can cause significant yield loss, but cotton can compensate for gaps shorter than a foot if they aren’t repetitive.
Thrips pressure is rising again after a brief respite with the storm, and wind or hail damaged fields tolerate fewer thrips than a healthy field can. Monti Vandiver, EA-IPM Parmer/Bailey, recommended an economic threshold of 0.5 thrips per leaf stage in hail or wind damaged fields. Seed treatments for thrips control are showing signs of losing residual, and thrips are reproducing in the fields.
When evaluating fields this week, be sure to check the stand of plants with healthy growing points, the number of thrips, as well as looking for wind and hail damage.
Kate Harrell is the 2013 intern for the Plains Pest Management Association. She is a native of Hale County and a veteran of our regional agriculture. Kate has just finished her bachelor’s degree from Texas A&M University in Entomology and will be starting her master’s degree in the fall. In between, we are happy to have Kate helping us this summer. We can expect more helpful tidbits from Kate over the next few months. Thanks, Kate!
Please call or come by if we can be of assistance,