Mother Nature blessed Georgia row-crop farmers in 2009 with perfect weather, which helped bring record-setting results. This year, however, she wasn’t as cooperative and sent the hottest April through September on record – the kind of weather that can hurt.
Heat makes diseases worse
“It has been difficult to battle disease with this heat,” said Bob Kemerait, a plant pathologist with University of Georgia Cooperative Extension. “White mold, leaf spot disease, southern corn rust – it has been a bad year for disease for our row crop growers and a lot of that is tied to weather pattern.”
Since July, white mold has caused the most problems for peanut growers. “The fungal structures of white mold were awakened by the extreme heat early in the growing season,” Kemerait said. “The scattered showers throughout the summer were like gasoline on a fire. This is the worst year for white mold in at least 20 years.”
But tomato spotted wilt virus, a disease that threatened to cripple the peanut industry in the 1990s, will likely affect less than 1 percent of the crop this year, he said. Improved varieties and management decisions by growers have made the disease less of a threat.
Peanuts need moisture
Peanuts not planted in fields with irrigation “are a disaster in some areas,” said John Beasley, a UGA Extension peanut agronomist. “Even irrigated crops have heat damage, especially the farms in the northwest part of the peanut belt that missed some of the rains other areas received.”
Without adequate moisture, peanuts can’t absorb the calcium they need to fully develop, he said. Farmers are harvesting peanuts now. The current clear skies, lack of humidity and breezy evenings are perfect for harvest.
According to the Georgia Agricultural Statistics Service, growers expect to yield an average of 3,300 pounds per acre, 7 percent less than last year’s record 3,560 pounds per acre average.
Growers are harvesting cotton now, too. “The yields are looking more and more optimistic as harvest progresses,” said Guy Collins, a UGA Extension cotton agronomist. “The hot, dry July could have severely reduced yield potential, but it doesn’t look as bad as we thought it would.”
According to GASS, cotton yields will average 761 pounds per acre, 16 percent less than last year’s record 902 pounds per acre average.
Heat affects cotton blooming
Intense July heat and dry weather shortened the bloom period for much of the crop, Collins said. A shortened bloom period, compounded by the return of rains in August, has caused new vegetative growth to develop. This is not good during harvest. New vegetation can stain or discolor cotton lint, resulting in a lower quality or higher trash content.
The top bolls, or the fruits that eventually open to make the lint, are immature or are otherwise difficult to open in some fields, he said, compared to bolls lower on the plant. The cooler weather could be causing them to stay closed.
“Hopefully, time and some warm sunny weather will help us out,” Collins said. “If it doesn’t open, it is rendered unharvestable. The top bolls mean more to the growers this year because prices are elevated. We are not dealing with exceptional yields in many cases. They are counting on those top bolls to earn a little more money.”
Two leaf spot diseases are causing problems in some fields, Kemerait said. Stemphyllium leaf spot disease causes leaves to fall off before a plant is mature, which prevents bolls from fully developing. Corynespora leaf spot causes rapid defoliation of plants and doesn’t allow the bolls to open properly. It is hitting fields in southwest Georgia.
Georgia soybean growers are expected to average 31 bushels per acre, 5 bushels off last year’s average. Soybean harvest is underway.
Corn harvest is complete, and growers expect to average 140 bushels per acre, matching last year’s record-setting average.
(April R. Sorrow is a science writer with the University of Georgia Public Affairs Office.)