Putting new peanut cultivars to the test
The new USDA breeding line may also help farmers with weed control

By Leeann Culbreath

November 10, 2005: The new USDA breeding line, C-11-2-39—proposed for release in the public domain—may also help farmers with weed control. It spreads well, shading many weeds with a thick canopy. It has also demonstrated excellent germination and strong disease resistance. “I was amazed. This variety was able to survive and thrive after an attack of fungus,” farmer Shirley Daughtry said.

“I was amazed. This variety was able to survive and thrive after an attack of fungus,”

Its nuts might not be large in size, but they’re huge in taste. Daughtry’s customers went nuts over the boiled goobers: “They were the most flavorful, sweetest peanuts we’d ever had,” she said.

Its red seed coat could pose a problem in processing, as most electronic machines in the South sort red seeds as defective. Processors may be able to recalibrate electronic sorters for specific varieties, if they are willing to absorb the time and expense for technical adjustment and batch segregation.

Seed availability will be an issue for some time as well, until a substantial amount is produced just for seed. Accordingly, most organic acreage this year is planted to Georgia 01R, also a resistant variety that spreads well and has excellent yield potential and a tan coating. However, it has had some germination problems, especially in Relinda Walker’s eastern Georgia field this year. “It was really sparse,” she said, “maybe a plant every few feet or so.”

While weather, soil temperature, and planting depth likely played a role, she won’t try 01R again. She plowed up all but four rows of it, which she maintained for research purposes. Emile DeFelice in South Carolina also had problems with germination and had to replant some.

As long as the plants emerge, the new cultivars provide the best line of defense against leaf spot and tomato spotted wilt virus.

As long as the plants emerge, the new cultivars provide the best line of defense against leaf spot and tomato spotted wilt virus—the most ubiquitous peanut diseases. Crop rotation, conservation tillage, and straw mulching are also effective, says plant pathologist Dr. Albert Culbreath.

This year, Culbreath’s team experimented with intercropping of different varieties, neem oil, and copper and biological fungicides for leaf spot management. Strip-intercropping with peanuts, cotton, and corn has helped reduce early leaf spot in experiments conducted for six years at North Carolina State University, Boudreau reported. Most peanut diseases are highly selective, and other crops can block disease spread. Straw mulching seems help, perhaps by interfering with inoculum splash (dispersal), he said.

In South Carolina, farmer Emile DeFelice plans to let his pastured pork forage the peanut fields after harvest to help reduce overwintering disease habitat. “Diseases are still a major obstacle for organic peanuts in the South, but now we have the tools to manage many of our important diseases pretty well,” Culbreath said.