By Travis Faske, Extension Plant Pathologist
During the 2017 cropping season there were reports of freeze injury on peanut in Arkansas. Those that were injured were dug a day or two before morning temperatures dipped a few hours below freezing (27 to 31°F). After a few days kernels with freeze injury could be detected. Those kernels were darker in color than non-injured kernels and often had a shriveled testa (Fig. 1). With the delayed harvest season this season, cold injury could once again become an issue so, here are a couple of reminders about avoiding freeze injury in peanut.
The main concern is for those peanuts that were dug a few days before the cold temperatures hit. Those peanuts that are recently dug and attached to the shell are more sensitive to the freezing temperatures than those that are dry. Loads with > 2.5% freeze injury are docked at the buying point. As a general rule of thumb, within 3 days of digging if the low temperature forecast is:
- 38°F or greater – keep digging
- 35-37°F – judgement call
- 34°F or less – stop digging
For example, if the forecast calls for 34°F on Sunday morning, stop digging on Tuesday. If the forecast calls for 37°F and only for a short period of time there may be little or no injury, but it is a risk. Once the threat of freeze passes then resume digging. Peanuts in the ground are safe; however, if a frost kills 50% of the leaves those plants should be dug within a week.