Thursday, February 9, 2023

The Search For 70%

A grouping of 70% to 75% orange, brown and black hull-scraped pod colors is a maturity level ready for digging. 

⋅ By Amanda Huber ⋅

Indeterminate. It means unknown, uncertain, imprecise and unclear. Unfortunately, that often describes knowing when to dig peanuts. 

As an indeterminate crop, peanuts will continue to grow vegetation while putting on new reproductive structures. Determinate crops, such as corn or wheat, stop vegetative growth when entering the reproduction state. That is why these crops mature more evenly. The continuous setting of new peanut pods throughout the season results in a wide range of pods in various stages of development at harvest.

A Critical Economic Decision

Determining when to dig is a difficult but critically important economic decision. Immature pods will not produce the desired yield, grade, flavor or subsequent crop performance. Overly mature pods may fall off the vine during digging or sprout in-shell in the field. Research has shown that digging a week early or late can decrease yield as much as 500 pounds per acre and reduce grade by several points. 

Days after planting is not a good gauge for when to dig peanuts, but it is a figure in which to start checking peanuts with the hull scrape method. In the color development of the mesocarp, orange, brown and black are the most mature.

The general progression of mesocarp color is similar across peanut market types; however, the associated days between stages may vary based on the maturity range of the particular cultivar. Runner peanut varieties are often categorized as medium at 133–139 days, medium-late at 140–145 days or late-maturing at 146–155 days. Early maturing would be prior to 133 days after planting. Medium maturity of a Virginia-type peanut is generally 130–135 days after planting. 

Use Days After Planting To Start Sampling, Not To Dig 

Most Extension publications recommend producers start spot checking maturity at about 120 days after planting. Use the pod blast or hull scrape method to expose the mesocarp, and then sort pods into color piles of white, yellow, orange, brown and black pods. If most of the crop is immature, a majority of pods will be white to orange. Place the samples on a maturity profile board to determine days until digging. 

he majority of orange, brown and black pods in this sample would indicate it is time to dig.

Optimum maturity for runners is 70% to 75% pod color in the orange, brown and black categories with a majority of brown and black. Add the combined number of pods from the brown and black classes, then divide by the total number of pods from the blasted sample for a maturity ratio. This calculation is sufficient to determine digging if the samples taken from a field average 70% at the optimal maturity level or higher.

The difficulty arises when the sample pods break down into two distinct groups of similar size with few pods in between. This bimodal distribution, or split crop, is often caused by drought or other extreme weather events when the maturity of the crop slows or nearly ceases. In this situation, a grower must decide whether to harvest the more mature group or wait and harvest the second group once it reaches maturity.

Other digging considerations include vine health, acreage, equipment availability and weather. Peanuts can wait for a time but, eventually, disease and pod loss will decrease yield. Use days after planting as a guide to start sampling for maturity and  hull color guidelines to verify that maturity. Disease control earlier in the season is critical to maintain the peg strength to carry peanuts to full maturity. PG

 

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