Working for (Better) Peanuts:
Black fungal bodies (sclerotia)
on infected peanut stems
under field conditions.
For a quarter century, scientists at ARS'
Wheat, Peanut, and Other Field Crops Research Unit in Stillwater, Oklahoma,
have worked to improve disease resistance and oil quality in peanuts.
The researchers, working in cooperation with Oklahoma
State and Texas A&M universities, used traditional breeding technology
to develop and release three peanut cultivars that resist Sclerotinia
blight, a disease that causes stem and peg rot.
Recently, two more peanut cultivars have been developed
that have caused a stir at the Oklahoma unit, which is part of the ARS
Plant Science and Water Conservation Research Laboratory. That's because
they're the first to posses both resistance to Sclerotinia blight
and a better-quality oil with high oleic acid content.
Plant pathologist Hassan Melouk, who leads peanut research
at Stillwater, says the two new cultivars are Olin, a Spanish variety,
and Tamrun OL 01, a runner type. He says the new varieties will have
the greatest benefit in states such as Oklahoma and Texas, where most
of the peanuts grown are runner and Spanish types. "These new cultivars
will increase the cash flow to peanut producers in those states by lowering
production costs and reducing reliance on fungicide use," says
"Peanut cultivars with high oleic acid ratios will
have a long shelf life, as well as health benefits for consumers,"
he says. "These lines are estimated to potentially enhance the
income of peanut growers in the Southwest by at least $10 million annually."
Oleic acid is a monounsaturated fatty acid credited with
benefiting the cardiovascular system. It also helps retard oil spoilage
and reduce off-flavor in stored peanut products.
Sclerotinia blight, which is caused by the S. minor
fungus, was first found on U.S. peanuts in 1971, in Virginia. It has
since been found in North Carolina, Oklahoma, and Texas. It has thrived
in Oklahoma and Texas because of increased planting of runner cultivars
that are susceptible to it.
The fungus forms seedlike structures and attacks plants
near the soil line, spreading rapidly across the peanut canopy. It survives
winter in the soil and attacks again, even if other crops are rotated
between peanut plantings.
Studies at Oklahoma State University have shown that yield
losses due to Sclerotinia blight range from 7 to 80 percent.
Before the release of the new cultivars, the only way of fighting the
blight was to use chemical-based fungicides such as Rovral and fluazinam,
which Melouk says are expensive and increase production costs.
"Farmers could save $125 to $135 an acre from not
having to apply chemicals," says Melouk. "In Texas and Oklahoma
alone, that's a potential savings of almost $10 million."
The two new peanut cultivars will be jointly released
soon, and seed should be available to farmers from seed dealers this
Meanwhile, research continues. Melouk says he and a colleague,
biologist Kelly Chenault, will explore creating still more new peanut
varieties through various means.By Luis
Pons, Agricultural Research Service Information Staff.
This research is part of Plant Diseases, an ARS National
Program (#303) described on the World Wide Web at www.nps.ars.usda.gov.
Hassan A. Melouk
is in the USDA-ARS Wheat,
Peanut, and Other Field Crops Research Unit, 1301 North Western
Rd., Stillwater, OK 74075-2714; phone (405) 744-9957, fax (405) 744-7373.
"Working for (Better) Peanuts: New Cultivars Resist Disease and Spoilage" was published in the August 2003 issue of Agricultural Research magazine.