It will be a few years before the complete package of the newest transgenic weed control technology is available to producers in California and Arizona.
However, the herbicide Ignite used in conjunction with LibertyLink cottons is now available in Arizona for use in standard cotton production system cotton varieties in post-directed or layby weed control applications. Ignite is expected to be registered in California later this year or early next. It controls almost 70 broadleaf weeds.
Bayer CropScience recently won federal registration for the use of Ignite over the top of five FiberMax/LibertyLink cotton varieties up until 70 days prior to harvest. However, none of the five are adaptable to Arizona or California.
However, California Planting Cotton Seed Distributors (CPCSD), Shafter, Calif., is developing LibertyLink Acala and Pima varieties which could be available before the end of the decade to San Joaquin Valley cotton producers.
Hal Moser heads CPCSD transgenic program and said the first Liberty Link Acala has been entered in the San Joaquin Valley Cotton Board testing program for possible release in three years as a replacement for the CPCSD BXN cottons, which are resistant to over the top Buctril herbicide applications.
“We are in the process of backcrossing the Liberty Link gene into Acala and we are seeing good quality fiber with very high gin turnout,” Moser told growers and consultants at a Bayer CropScience seminar recently.
Acala/Liberty Link cottons will be the first to market with hopefully Pima/Liberty Link cottons by the end of the decade. It is proving more difficult to develop transgenic Pimas.
Useful in Arizona
University of Arizona weed control specialist Bill McCloskey said Ignite, which once was called Liberty herbicide, works well in Arizona when used in tank mixes in a post directed weed control program in conventional cotton.
“Ignite provides good control when used with Prowl,” said McCloskey. It is especially effective on pigweed and slows morningglory.
“It is critical to treat when the weeds are small and sequential applications are important to achieve total control,” he said.
“We are very excited to get this new technology in the marketplace to compete with the Roundup Ready system. We look forward to eventually getting LibertyLink adapted varieties for Arizona,” he added.
His counterpart, weed control specialist Ron Vargas, a farm advisor in Madera County, Calif., strongly echoed McCloskey's point about treating weeds early.
In trials, Vargas found control was cut almost in half when treating weeds at the five-true-leaf stage vs. the four-leaf stage.
“Stage of growth is extremely important to control,” he added.
“We were able to increase control with Ignite when we used it in conjunction with Staple,” said Vargas.
Vargas said 40 percent of the upland cotton varieties planted in California last season were resistant to either Roundup to Buctril.
This is saving growers up to $25 per acre or more in weed control costs reducing by hand hoeing expenses. It is also is allowing growers to adopt conservation tillage practices by reducing cultivations, using over the top herbicides on resistant cotton varieties instead.
However, Vargas has long sounded the alarm that there may be a price to pay this technology: herbicide resistant weeds. Already Roundup-resistance has been documented in annual ryegrass and marestail. Also Vargas said growers are reporting to him poor control of barnyard grass and lambsquarter with Roundup.
Ignite offers an alternative mode of action for resistance management and also has show good control on tough pigweed, nutsedge, hairy nightshade and puncturevine.
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