Disease pressure could influence peanut digging

The amount of disease you've had in your peanut fields may be the best measure in determining when to dig in the Virginia-Carolina region this season. As the time for digging moves closer, farmers in the region are looking at the result of heavy disease pressure.

“I'm afraid we're going to have to dig some peanuts on the early side,” says Billy Griffin, Bertie County, N.C., Extension director. Griffin, along with other county agents, is planning to hold pod-blasting clinics to help farmers determine the optimum time to dig their peanuts.

Rainfall, cool nighttime temperatures and diseases are dictating much of the digging decisions this season. In early June as much as 12 inches fell in some parts of the peanut belt in North Carolina. In Virginia, web blotch made an earlier-than-usual appearance in June, prompting some concern among specialists and growers.

“We've had a tremendous amount of web blotch, with lots of defoliation,” Griffin says.

Web blotch also caused problems for growers last year toward the end of the growing season.

Griffin has been advising the farmers in Bertie County to stay on a strict, seven- to 10-day spray schedule in order to keep the leaves on the plants.

Web blotch, which usually occurs from early- to mid-September, causes spots on the leaflets and leads to defoliation. The earlier it occurs, the greater the risk to yields says Pat Phipps, Virginia Tech plant pathologist.

In Virginia last season, farmers who had the most problem with web blotch suffered 30 percent losses in the worst-case scenario.

In Bertie County this season, Griffin says he's seen fields where 80 percent of the leaves are affected with web blotch.

Mixed together with tomato spotted wilt virus, black root rot and Sclerotinia, the high incidence of web blotch is causing concern at harvest time, Griffin says.

While it's important to monitor and treat the fields for diseases that could speed up the process of pods dropping off the vines, it's also important to know where the crop stands in regard to maturity.

That's where the pod-blaster comes in.

The decision to dig is more of a field-by-field matter than when the crop was planted or even what variety was planted, says David Jordan, North Carolina State University peanut agronomist. “You really can't use the calendar,” Jordan says. “You have to get out in the field and sample where the crop is.”

The pod-blasting method speeds up the process, giving the farmer a larger sample to work with. Glass beads in a solution of water remove the outer layer of the peanut pod, revealing the maturity level of the mesocarp layer. “The level of maturation is reflected in the mesocarp,” Jordan says. “If it's black or brown, it reflects a mature peanut. Yellow, orange or white reflects those peanuts that are not mature.”

County agents in the peanut-growing areas of the V-C schedule pod-blasting clinics in mid- to late-September and into October, Jordan says.

In Bertie County, Griffin tries to schedule the pod-blasting clinics within a two-week span of when farmers need to start digging. He divides the county into three sections and conducts three clinics. He'll start first with the early-maturing varieties.

“The use of the pod-blaster to determine maturity has been one of the most successful programs we've ever initiated in the county,” Griffin says. “From the tests we ran, we found out that there were drastic differences in yield and maturity if you didn't dig at the optimum maturity level,” Griffin says.

“Farmers have been very receptive to pod blasting,” Griffin says.

Jordan says the numbers show that a grower can pick up an extra $6 to $11 per acre based on harvesting at optimum maturity. “That doesn't mean you always pick that up, but on average you increase yield by about 300 pounds and quality by about 1 percent to 2 percent.

“Waiting a week could mean an extra $50 or so,” Jordan says. “You're losing water and gaining oil when you wait until the optimum time to harvest. Harvesting too early or too late can cost you.”

e-mail: [email protected]

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.