Cotton producers should not form deep, emotional attachments with the varieties they grow. If they do, Extension cotton specialists say, they may just come away from the experience with a broken heart.

That's because today's varieties, while producing higher yields and, in some cases, better fiber quality than in the past, can be a fickle lot, waltzing into cotton growers' lives and then waltzing right back out again.

“The old way of selecting varieties was to look at a variety at several locations over three, four or five years,” says Michael A. Jones, Extension cotton specialist at Clemson University. “Those days are past. By the time we get comfortable with those varieties for two or three years, there's a new version of that variety.”

Speaking at Cotton Incorporated's Crop Management Seminar in Memphis, Jones said the high rate of turnover is a product of seed companies' desire to incorporate new transgenic material into their brands as quickly as possible. The result: an explosion of new varieties.

“In our official variety trials this past year, we looked at 80 to 85 varieties, many of them versions of the same variety with different transgenes in them,” said Jones, who is based at the Pee Dee Research and Education Center near Florence, S.C.

“So it becomes very complicated for us to evaluate them, and it's even more complicated for growers to get good experience with varieties and to make good decisions on what they need to put on their farms.”

The high turnover rate of all but a handful of varieties makes it imperative for crop consultants and producers to “do their homework” before recommending or selecting specific varieties. Special attention should be paid to yield potential and yield stability, he said.

“You should study the data from the official variety trials and look at the different environments that are relative to your state and your county,” says Jones. “These trials are planted on different soil types and managed differently for the various locations. And they have different weather that can affect yield and quality.”

Most land-grant universities conduct their official variety trials at a number of on-farm locations. Clemson has increased the number of on-farm tests significantly from the two sites it operated when Jones first went to South Carolina.

Jones urges growers and consultants to take all the variety information they can find, format it and use it to make decisions about which varieties might work best on their farms.

“Growers also need to temper that data with their local experience,” he said. “If they find a variety that's working on their farm, even though it's not the top variety in the OVT, they probably need to stick with that variety because it may be well-suited for their management and their soil conditions.”

With the different maturities that are now available in the transgenic varieties, farmers can more easily spread their risk over varieties, maturities and planting dates. When the first Bollgard and Roundup Ready varieties were introduced, the maturity range was four or five days. In the second generation of those technologies, it can be up to two weeks.

Don't buy more technology than you need, says Jones. “Bollgard II and Roundup Ready Flex are great technologies, but there's a lot we need to learn about this technology that we don't know. We would be wise not to put all our eggs in one basket and spread the risk over the different technologies.”

Growers should also be aware of the potential for yield differences in some of the new transgenic cotton.

“In the Southeast, the straight Roundup Ready varieties or the straight Roundup Ready Flex varieties may not be the best choice for high-yielding, two- or three-bale land,” says Jones.

“When you think about where these varieties are falling in the official variety trials, they are normally an average to above average variety. With a low yield potential, you may be talking about a 50- to 75-pound lint difference. But if you put them on a two- to three-bale field, you may be talking about a 300- to 400-pound difference.”

A final recommendation: Buy quality seed. “With the amount of money growers are spending on seed today, they need to get the best germination they can.”

Jones notes that some Southeastern growers have found a variety they apparently like. In 2006, Deltapine 555 BG/RR was planted on 9 percent of the cotton acres in North Carolina, 46 percent of the cotton acres in South Carolina and 77 percent of the acres in Georgia.

“Georgia is very heavy into 555,” he said. “One thing that would concern me is that they don't have a lot of variability in what they're planting. If they ever have a problem with Triple Nickel — which has not shown up over the past five years — there could be some management issues there.”

Because DP 555 BG/RR does have small seed, Jones noted that Georgia Extension specialists Steve Brown and Phil Jost recommend that growers (1) don't plant it too early; (2) don't subject it to emergence challenges such as cool temperatures and wet conditions; and (3) don't forget to use the proper seed spacing.

And because it is a full-season variety, growers should not (1) plant it too late (2) abuse it with glyphosate; or (3) let insects take the early fruit. In most situations with DP 555 BG/RR, growers should apply plant growth regulators early. But only if good growing conditions exist.