Transgenic peanuts that offer resistance to peanut leaf spots and could significantly reduce production costs, are among research programs that hold promise of benefits to growers in years ahead.
“We have an experimental transgenic peanut that appears to have extremely high resistance, or even borderline immunity, for early and late leaf spot,” says Marshall Lamb, research director for the USDA/Agricultural Research Service National Peanut Research Laboratory at Dawson, Ga.
“In greenhouse work, we never had to spray for leaf spots — you couldn’t find a lesion anywhere on the plants,” he said at the annual meeting of the Mississippi Peanut Growers Association at Hattiesburg. “These have been turned over to Auburn University pathologists, who will challenge them with leaf spot inoculum and do initial testing to determine resistance levels.
“We’re very excited about the potential for this variety. It could mean you might never have to spray for leaf spot again (which in our area is every 10 days to 14 days). That would be a major benefit for growers. Also, the parent is from a very high yielding line, which could mean a very productive, leaf spot-resistant peanut.”
Lamb emphasizes that there are no transgenic peanuts in edible markets today, that the varieties “are only in the experimental stage, and it will be years before any transgenic varieties will even be considered for release.”
In other variety work, he says, Auburn University and the National Peanut Laboratory have an extensive breeding program that includes a number of promising experimental lines.
“In tests over four locations, GA 06G averaged 5,900 pounds, and we had yield from one of the experimental lines that averaged 6,016 pounds.
“Another that we’re particularly interested in averaged roughly 5,900 pounds, equal to 06G, but if you compare the weight of 100 seed, it’s much smaller-seeded than O6G. This will not only save money for producers on seed cost, it will also give shellers a more uniform outturn. That’s important, enabling them to sell to multiple markets instead of having a lot of jumbos to deal with.
“We expect these varieties to be released or available for seed increase soon. Several of the varieties in this research look extremely good and we’ll keep pushing forward with them. We should have them in our Mississippi tests this year.”
Another research project outlined by Lamb is aimed at improving maturity distribution in peanuts by chemically halting flowering late in the growing period.
“When you’ve got peanuts that are far black, or approaching far black on the maturity profile board, there is a point that additional flowers will develop pegs and pods, but those pods have no chance of helping with yield or grade. They’re taking energy away from the plant that could be used by the more mature, higher-yielding, higher-grading peanuts.
“Immature peanuts can also take away from grade, because they can cause problems with flavor — that was the original aim of this research, to improve flavor by reducing the immatures.
“In tests at two locations in Georgia and one at Walnut Ridge, Ark., we terminated flowering at about day 100. One of the compounds is diflufenzopyr Na, an experimental chemicalfrom BASF that is not yet approved for use; the other is generic glyphosate.
“The glyphosate was applied at the rate of 2 oz., 4 oz., and 6 oz. per acre. Generic glyphosate is cheap at the full rate, and it is particularly cheap at these low rates.”
From day 100 through day 120, on three-foot rows, plants were producing an average of 14 new, viable flowers every day, Lamb says. The chemical treatments reduced that to 2 to 3 flowers each day. And even in the flowers that remained, the pollen wasn’t viable. In other plots, flowers were hand-removed for 20 days.
Significant increase in maturation
“We saw a significant increase in maturity in older peanuts after flowers were removed,” Lamb says. “Reducing flowers, whether chemically or by hand, increased the rate of maturation over the control plots by three-fold and four-fold amounts. Grades were also increased.
“Yield for irrigated peanuts was increased by as much as 700 lbs., much of that due to kernel density — the peanuts that remained were heavier, which translated into higher yield and grade.
“It’s hard to convince a farmer to take flowers off his peanuts — but at a certain time in the crop’s development, new flowers will only make new pegs and peanuts that take energy away from the more mature peanuts. If we halt that process, that energy can go toward a better maturity distribution, and hopefully better yield and grade.
“We will expand the study this year, and hope to include a Mississippi location.”
Irrigation scheduling studies are also continuing, Lamb says. “If you look at Farm Press Peanut Profitability Award winners, or yield achievement winners, many of those use Irrigator Pro. It has been proven by farmers and by consultants on over 60,000 acres.
“If you’re interested in it, contact us. Through collaboration with IBM, we’ll have it on the Web, and it will also be available for smart phones. There is no cost to growers.”
Other research is evaluating the use of peg strength as a tool to estimate maturity and determine when to dig.
“If you’ve got good peg strength on the black peanuts on your maturity board, you can wait a bit to dig,” Lamb says. “We use a digital force gauge to map the entire peanut plant. We then take one pod and blast it, and what we’re finding is that — based on peg strength, plant health, and cultivar — we can leave peanuts in the ground longer. The longer they can stay, the higher quality they’re going to be in general.
“We’re going to keep working with this and hope we can offer growers a tool to help them delay digging in order to get higher yielding, higher grading peanuts.”
Data have been collected for 2012 for X-ray grading of peanuts, Lamb says. “We’re comparing grading factors from the X-ray process with federal/state grades, and results have been quite similar.
“We don’t have all the data analyzed from 2012, but from a cursory examination, results look quite good and we hope to publish our findings soon."