LUBBOCK – Some Texas producers are busily harvesting their 1999 peanut crop. Field reports so far indicate a good crop, but some growers and buyers are wondering how cooler fall weather will affect unharvested peanuts, said a Texas A&M University agronomist.
“Most of this concern is due to moderately strong cold fronts that have passed across the state this month with some regularity,” said Robert Lemon, Texas Agricultural Extension Service agronomist in College Station. “At this time of year, windrowed peanuts are often subjected to near- or below-freezing temperatures as these fronts pass through.
“Kernel damage can occur if there is a wide variation between cold low temperatures and warm daytime temperatures. Recently dug, high-moisture peanuts are especially susceptible. But moisture content isn’t the only determinant in kernel damage.”
Actual air temperature, exposure time and the extent of warming the next day also interact with moisture content to contribute to kernel damage. So many contributing factors makes predicting freeze damage a tough call, the agronomist added.
“Peanuts have an indeterminant flowering habit kernel maturity and size varies greatly on any given plant. Younger, immature kernels with higher moisture content are most susceptible to freeze damage,” he said. “Cold temperatures change seed respiration from aerobic (with oxygen) to anaerobic (without oxygen).
“Anaerobic respiration increases concentrations of several volatile compounds such as ethanol and acetaldehyde, and causes plant cells to leak organic and inorganic materials. This often causes a fruity, fermented off-flavor. Smaller, cold-susceptible kernels (No. 1’s) are much more susceptible than medium- or jumbo-size kernels.”
Delaying digging until after a cold front passes is a good strategy for minimizing cold exposure and potential freeze damage, he added.
“Soil is a good insulator. It will protect underground peanuts from air temperatures that are 3 to 5 degrees below freezing. Even so, vines and peg attachment will deteriorate quickly after cold weather, so it’s important to dig peanuts promptly after freezing weather has passed,” Lemon said. “Peanuts windrowed with a sandwich digger also have some protection from cold temperatures.
“Sandwich diggers deposit upright plants on inverted plants, so the windrowed peanuts are insulated top and bottom by plant vines.”
To minimize the potential for freeze damage, peanut producers should keep an eye on regional weather forecasts, know their crop’s maturity and moisture content, and delay digging until after a cold front (if possible), Lemon said. The National Weather Service’s Southern Region Office Web site http://www.srh.noaa.gov is a good source for current weather forecasts, he added.