By Travis Faske, Extension Plant Pathologist
Unlike other row crops, peanuts are not terminated by shutting off the water but rather by digging and inverting the crop (Fig. 1).
Currently, there are a few fields that are being dug across the state, but determining when to dig is an important decision that should not be taken lightly. If a crop is harvested before it is mature, it can result in a yield loss of 200 lb/ac or more. Generally, runner peanut matures in 140 to 150 days after planting, but the best measure of crop maturity is based on the color of the pod mesocarp. Pod blasting, as it is commonly called, is the process by which the hull is removed to expose the mesocarp, which progressively gets darker in color (from yellow to black) as the pod matures. A power washer can be used to remove the hull (Fig. 2) from the pod.
To estimate maturity, one hundred pods are hand pulled from the peanut plants collected at various locations in the field. Pods are grouped by color on a peanut profile board to predict a harvest date (Fig. 3) when 70-85% of pods are estimated to be mature. Typically two samples are collected per field, the first sample at 120 to 130 days after planting and then a second at 10 days before the predicted harvest date to ensure the field is ready.
Inverted plants are allowed to dry in row for 3 to 5 days until pods are dry and ready to be thrashed from the vines. Rainfall during windrow drying shortly after digging may promote mold and lower the grade value; therefore, it is desirable to dig when the long range forecast predict dry weather conditions. Peanut harvest is more like harvesting a vegetable than a row crop as it is a much slower process than soybean or corn harvest. Typically, a producer can harvest 30 acres of peanuts in a day depending on yield and trailer availability.