The recent 2009 Sunbelt Expo Field Day in Moultrie, Ga., treated visitors to a preview of more than 100 in-field crop variety trials in addition to cutting-edge agricultural technology and suggestions on handling some of the more pressing fertilizer and pest control concerns on growers’ minds.
The University of Georgia Extension Cotton Team is focusing on several production issues at the Expo site, including soil fertility and stink bug management.
“Fertilizer prices really began increasing in about 2005, and hopefully they peaked last fall,” says Glen Harris, University of Georgia Extension agronomist. “Nitrogen and phosphorus have come down in price significantly, but not back to where they were, and potassium has not come back down.”
Potassium, however, is needed by cotton, he adds. “With some of these newer cotton varieties, we’re just not sure how they’ll respond to potassium compared to standards like DPL 555. At the Expo this year, we’re looking at potassium treatments on three different varieties — DPL 0935, DPL 0949 and DPL 555. Our standard recommendation would be for about 90 pounds of potash, but we’ve put out 45, 90, 145 and 180 on these varieties, and we’ll see what happens,” he says.
Some private laboratories, says Harris, recommend significantly higher levels of phosphorus than those suggested by the University of Georgia.
“Potassium nutrition is very important to cotton. Many times, we get leafspot on cotton. When we get it early, it can hurt our yields, and it’s usually due to a calcium deficiency,” he says.
Research at the Expo also continues to look at nitrogen additives like Agrotain and Nutrisphere, says Harris. “Last year, we followed peanuts in our cotton plots and didn’t get a lot of response from these materials. I think these products work in situations where you typically would get a response from nitrogen.”
Field trials also are being conducted to verify thresholds for treating stink bugs, says Phillip Roberts, UGA Extension entomologist. “For several years now, we’ve been looking primarily at stink bug management here at the Expo site. We can do longer plots here than at our experiment stations,” he says.
For the past several years, Georgia has cooperated in a project with other Southeastern states to continually improve the management of stink bugs in cotton, says Roberts. “This is especially important as we move to two-gene Bt cotton. Our management of stink bugs probably will be the primary component in our cotton insect management programs. Particularly in mid- to late-season, these programs will revolve around stink bugs,” he says.
Research is exploring “dynamic thresholds,” says Roberts, where growers will be more aggressive about treating for stink bugs during the critical windows.
“The third, fourth and fifth week of bloom are very important in doing a good job managing stink bugs in cotton,” he says. “Think about how a cotton plant grows and develops during that window — that’s when you have the greatest number of bolls on the plant that are susceptible to stink bugs. When we get late in the bloom, a lot of the bolls become too old.”
Researchers, says Roberts, continue to build on a multi-state database. “We’re also trying to better understand how stink bugs are moving across the farmscape. The Expo is a good site for this because of the large variety of crops here. We’ll be coming up with some innovate approaches in the next couple of years,” he says.
Peanut producers now have a wide variety of peanut cultivars from which to choose, says John Beasley, University of Georgia Extension peanut specialist. “Last year, growers had a choice of about 15. This year, there are 11 or 12 options, and growers are always trying to determine which one or ones will work best in their operations,” he says.
There are many ways of comparing cultivars, says Beasley, and research at the Expo site is focusing on row patterns.
“We’ve been looking at the twin-pattern compared to our traditional single-row pattern since the mid-1980s. We look at these each year. Every cultivar that has been released since Florunner has been compared on twin and single rows. In our Expo plot, each cultivar was planted in two rows, with each being 300 feet long. There were three replications, planted on May 7.
“Our analysis from last year showed there was no interaction between the cultivars and row patterns. It did indicate that there was a significant yield advantage for twin rows over single rows in the 15 cultivars we tested. The cultivars 3G and C99R were the only two that had higher yields in single rows, and in both cases, it was a very small difference,” says Beasley.
Over the 15 cultivars, there was a 344-pound yield advantage in the twins over single rows, he says, and it’s not uncommon to see yield differences of 400 to 600 pounds in twin rows.
“We’re repeating the trial this year, but we’ve reduced the number of cultivars from 15 to 10 because seed no longer is available for some cultivars. We also left out the late-maturing varieties because we were harvesting them at about the same time as the Sunbelt Ag Expo in October,” he says.
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