University of Georgia Extension Cotton Specialist Steve Brown can't remember irrigated plot yields ever falling below 1,000 pounds per acre, but it happened during the 2000 season.
"This is my 14th cotton crop in Georgia, and I can't remember our variety trial yields ever falling below 1,000 pounds per acre. But our maximum plot yield this past year was 750 pounds per acre, in irrigated fields," said Brown at the recent Georgia Cotton Production Workshop held in Savannah.
In reviewing Georgia's 2000 cotton crop, Brown said USDA numbers showed the state's planted acres at just under 1.5 million while harvested acres were about 1.3 million. Average yield per harvested acre was 596 pounds with about 200,000 acres abandoned due to drought and other problems.
"Climatologists correctly predicted that the 2000 production season would be plagued by drought," says the agronomist. "Drought has persisted since June of 1998, and much of the state has experienced rainfall deficits in excess of 30 inches during the past couple of growing seasons. The summer-long drought followed by September tropical storms put a double whammy on much of the 2000 crop, resulting in the fourth consecutive dismal crop."
Growers thought 1999 was a bad drought year, he adds, but 2000 proved to be even worse. "April was a fairly normal month for rainfall, but May, June, July and August all were below average in rainfall amounts, particularly August. Maximum temperatures also were above average. The cumulative effect of heat and drought was profound," he says.
Disappointing overall Production was disappointing on both dryland and irrigated acreage, notes Brown. "If we say that 40 percent of our crop is irrigated, then we should easily be averaging 700 to 750 pounds per acre statewide. But in the last three to four years, we've seen yield averages fall from 708 pounds per acre to about 600 pounds because of back-to-back bad crops. Many irrigated fields produced 200 to 300 pound per acre less than anticipated, underscoring the effects of weather."
About 35 percent of Georgia's crop this past year was planted in stacked-gene varieties, with both the Bollgard and Roundup Ready technology, says Brown. Another 31 percent was planted in strictly Roundup Ready varieties while about 13 percent was planted in Bollgard varieties. About 20 percent of the state's acreage was planted in conventional varieties while less than one percent was planted in BXN cotton.
Drought and heat stress also have reduced fiber length and have increased micronaire in Georgia's crop, he says. "Fiber quality has become a serious issue for Georgia growers, especially in the area of staple length. In 1998 and 1999, we saw extremely short staple lengths. We actually have improved, with an overall staple length of 34.2.
"At one point in the harvest season, about 85 to 90 percent of our crop was short staple, but we began to see some improvement. The most recently harvested crop is running at about 18 percent short staple. We should end up the season with about 28 percent of our crop classed in the short staple range. With our steady improvement this year, we're now on par with the other classing offices in the South."
About 23 percent of the crop - through Nov. 24 - graded "light spot" or worse, reflecting rainfall during the first three and a half weeks of September, especially throughout the central corridor of the state, says Brown.
"The uniformity index also has been a problem for us over the last couple of years, even to the point of textile mills wanting to discriminate against our cotton. What's the cause? Uniformity sometimes is affected by short fibers. It could be aggressive ginning, or, in some cases, we're making some of our top crop that we haven't made in the past that other portions of the Cotton Belt aren't making.
Some improvement "We saw some improvement this year - our uniformity index is up a little. If this number continues to improve, it'll be positive for us in terms of the cotton industry. We're looking to research to help us explain the impact of various production practices on uniformity."
Other problems related to heat and drought stress during 2000 included premature defoliation and uneven growth, says the agronomist.
"Under severe and intense drought, our irrigation systems simply couldn't keep up. In many cases, after the rainfall in September, we had a beautiful and showy top crop, but we saw very few bottom bolls and significant boll rot low on the plant. The cotton looked exceptional, but it was mediocre in many fields."
In areas near Hazelhurst, Ga., some growers saw significant problems from fusarium wilt disease, says Brown. Other producers saw severe lodging, and it wasn't limited to a particular variety, he adds.
"For the most part, worm pressure was light in Georgia. There was some heavy pressure reported in the extreme southwest corner of the state, but worm sprays were two or less in many parts of the state. Aphid pressure was severe over much of Georgia. The pressure was widespread and prolonged.
"In addition, stink bugs have become a prevalent pest and white files were a problem in the Tifton area. Altogether, insect sprays were two to two and a half per acre. On Bollgard cotton, it was closer to one spray per acre."