New cotton weed technology promising

Roundup Ready technology is the 800-pound gorilla of weed-control in cotton farming, and that's not likely to change anytime soon.

But a handful of producers still insist on having their cake and eating it too. They want effective weed control and more flexibility often associated with conventional cotton varieties. One expert believes two new technologies on the horizon may provide some producers with these advantages.

Liberty Link cotton, manufactured by Bayer, is a transgenic variety similar to Roundup Ready. It's also effective on many of the same weeds — though a little better or weaker — depending on the weed, says Mike Patterson, an Alabama Cooperative Extension System weed scientist.

On the other hand, Liberty Link is used with the herbicide gluphosinate rather than glyphosate associated with Roundup Ready cotton — a factor that allows Liberty Link to tolerate more herbicide sprayings. “With Roundup Ready cotton, you get tolerance only up to about the fourth leaf,” Patterson says, “and you're not supposed to spray over-the-top beyond the fifth leaf. After that, you have to go to post-directed spraying.”

With Liberty Link, on the other hand, you can spray up to the tenth leaf, thereby freeing the producer of the added complication and expense associated with post-directed spraying.

Even with these advantages, Liberty Link cotton is no panacea. While Bayer is expected to wave technology fees, acre-by-acre application rates for Liberty Link still may be more expensive than Roundup Ready.

An added disadvantage is that only a limited amount of seed will be available this year, Patterson says. And since this will be divided among the 18-cotton-producing states, each state will end up with only a few thousand planted acres of the new cotton.

One other product that will afford some producers with more flexibility is known by its brand name Envoke, manufactured by Syngenta. Unlike Liberty Link, Envoke is a conventional herbicide that can be used on all cotton varieties — transgenic and conventional alike.

That's a plus for some producers, because it will enable them to switch back to the flexibility often associated with conventional cotton varieties. Add to that Envoke's effectiveness on sicklepod and morningglory, and you have what Patterson considers a winning combination.

“Some of our conventional varieties appear to have a little better grading quality than the transgenic varieties,” he says. “That certainly doesn't apply in every case, but the fact remains that there are conventional varieties out there that are better from the standpoint of grading and fiber quality, and that translates into a better price.”

Envoke also works effectively at very low rates of application — about one-tenth of an ounce an acre, which amounts to about a half teaspoon.”

Even so, while Envoke can take out many of the most important broadleaf weeds, it is not effective on small-flower morningglory, a perennial problem in southeast Alabama and southwest Georgia. An added disadvantage is that at the rate it will be used with cotton, it will not be as effective as Roundup Ready cotton in controlling grasses. This means growers will have to use other herbicides at planting for effective control.

Availability is another problem, at least for the foreseeable future. Envoke apparently will not be obtainable with a full label until next fall — effectively eliminating it during the 2003 growing season, though Patterson and other experts are lobbying for an earlier use application for Alabama producers.

While neither of these technologies, Liberty Link and Envoke, will replace Roundup Ready cotton, Patterson believes they ultimately will be valuable tools for some producers looking for more flexibility.

Also, by rotating these technologies, growers may be better equipped to cope with the added challenge of weed resistance, a problem that will almost certainly arise with Roundup Ready technology.

Most important of all, he says, is that the convenience afforded by these chemicals will provide some producers with the means to compete more effectively in an increasingly global farming economy.

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