High Plains
The Freeze & Frost of October 8, 2012
An unexpected heavy frost/freeze occurred in the lower High Plains region on October 8th. Due to later plantings, often after failed cotton, many acres were subject to extended hours of frost and freeze. Lubbock recorded the second earliest freeze on record (average first freeze is Oct. 31). Texas Tech Univ. “Mesonet” weather stations (http://www.mesonet.ttu.edu) recorded lows of 28°F at Muleshoe, Floydada, Hart, and as far south as Tahoka.
Frost damage and termination of grain sorghum is well known in the High Plains but rarely catches much sorghum that is not yet mature. Early assessment suggests significant foliage damage is present. How some sorghum fields respond may depend on stalk (culm) survival from the head down into the foliage. If the culm survives the freeze then the plant can continue to deliver nutrients and carbohydrates to the developing grain. But at a minimum, I expect reduced test weights on many acres of grain and in some cases little to no further grain development as the grain will now simply dry down without further starch accumulation. This is particularly a concern as numerous fields appear to be in the range of seed development at 20% hard dough/60% soft dough/20% milk stage, with 5% of the total grain at black layer (physiological maturity). Fields that show evidence of major injury which were likely >50% milk stage should be considered for hay or grazing.
For additional information on handling grain sorghum damaged by a freeze, consult “Harvesting Grain from Freeze-damaged Sorghum (~2001)” from Kansas State Univ., http://www.agronomy.ksu.edu/extension/p.aspx?tabid=86. This includes decisions for low test weight grain sorghum, which is price discounted, and may be rejected outright if test weight is <50 lbs./bushel. If faced with low test weight, compare discounts among local and regional grain buyers. Allow time to take a preliminary test cutting to assess your test weight. If low, you may reset the combine to blow out more of the lighter immature kernels.
Freeze damaged grain sorghum on a pound-per-pound basis has similar feed value to mature grain, however, the small kernel size makes grinding more difficult in order to crack the seed and capture the grain’s full nutritional value.
Texas AgriLife will post additional information on the regional grain sorghum freeze discussion at http://lubbock.tamu.edu in mid-afternoon on October 10th.
