Virus, weather plague Georgia peanuts

Less-than-ideal weather conditions and the worst outbreak of tomato spotted wilt virus in several years all but guarantee that most Georgia peanut producers this year will harvest well below last season's bumper crop of 3,300 pounds per acre.

“I don't expect we'll make the initial September estimate of 3,000 pounds per acre,” says John Beasley, University of Georgia Extension peanut specialist. “It looks closer now to 2,600 to 2,800 pounds per acre. We need for all of these weather systems to clear out so we can get in the fields.”

Weather conditions throughout Georgia were dry during August and early September, he says, only to be followed by a tropical storm and the remnants of a hurricane in mid-September.

Tropical Storm Hanna was a blessing for some growers, he says. “It pulled some of this crop out of drought conditions. It didn't turn the crop around, but it helped it hold its own.”

The Georgia crop matured earlier than normal this year, says Beasley, and cooler weather conditions late in the season have triggered diseases such as late leafspot and rust. Tomato spotted wilt virus has been a problem throughout the growing season, he adds.

More than 90 percent of Georgia's 2002 crop was planted after May 1, resulting in the majority of the crop being harvested beginning on about Sept. 10 and later, says Beasley.

This year's growing season started out much like the previous five years — dry, says the agronomist. Rainfall was well below normal in May, and many growers were forced to delay their original planting date.

Approximately 70 percent of the crop was planted during the three-week period from May 5 to May 26. “This was expected since a very high percentage of growers are following the Tomato Spotted Wilt Virus Risk Index. This year, however, there were big differences within planting dates during the May 1-21 planting date window.

“Some of that difference possibly could be explained by the fact that there was a slight cold spell in mid-May that could have had some bearing on thrips activity and the transmitting of the virus to sluggishly emerging plants,” he says.

More than 35 percent of the state's peanut acreage was planted after May 19, adds Beasley. “Typically, we'd like to see the majority of the peanut crop planted by May 20. Dry weather delayed the planting on non-irrigated fields.”

The incidence and severity of tomato spotted wilt virus has been worse on peanuts this year than it has in several years, he says. The loss in yield and dollars to the virus peaked in 1997. Since then, notes Beasley, growers have been following the risk index, and the level and the severity of the disease has dropped from 1998 through last year.

“This year, however, the virus was back with a vengeance, and the reasons can't be fully explained. Outside of water, tomato spotted wilt virus now is our number one yield-limiting factor. If growers do not do everything possible to reduce their risk to the disease, then yield potential is reduced severely. Genetic resistance in the form of new varieties is our best hope for handling this problem.”

Thrips were prevalent in Georgia peanut fields this year and caused heavy damage in some areas, says Beasley. During dry weather periods, lesser cornstalk borer reduced plant stands and fed on newly developing pegs. By early July, leafhopper damage also was a problem in some fields, he adds.

The major insect problem affecting Georgia peanuts in 2002 was beet armyworms, he continues. “These foliage-feeding insects are difficult to control, and they were defoliating a number of fields.

“As luck would have it, the EPA approved the label of Steward insecticide in early July. Steward is very effective on beet armyworm, and this saved a number of fields from significant yield loss. Other foliage-feeding insects, especially fall armyworms, also infested some fields. These insect problems resulted in growers having to treat fields that normally would not have been treated with insecticide, thus increasing cost of production.”

Weed control in this year's peanut crop either was outstanding or poor, says Beasley. Nutsedge was prevalent in many fields and pigweed continues to cause problems for many growers, he says.

“As the season progressed, Florida beggarweed began to emerge. The price of Cadre herbicide was reduced to a level that as much as 75 to 80 percent of Georgia's peanut acreage was treated. This could cause problems for cotton producers as the Cadre label requires a plant-back restriction of 18 months for cotton in a field where Cadre was applied to peanuts.”

Seed suppliers report that 80 percent of Georgia's 2002 peanut acreage was planted in the Georgia Green variety, says Beasley. These same sources indicate that 11 percent was planted in AgraTech 201 and 9 percent in C-99R.

“Georgia Green has performed very well under some very stressful, as well as very good growing conditions. It has a good level of resistance to tomato spotted wilt virus and has a mild maturity range. Seed quality for this year's crop was very good. We saw few stand problems related to seed quality.”

Prior to the onslaught of tropical storms and hurricanes, beginning the second week in September, there had been just enough scattered rain in Georgia to avert a total disaster, says Beasley.

“Some fields had enough rainfall to prevent plants from wilting while others received well below normal amounts of rain. During the critical pegging, pod development and pod fill stages, a peanut needs two inches of water per week. Most of Georgia's crop was in these stages from mid-June until early September.”

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