Crop Tech

August 27, 2008 03:28 PM

Bad News for Weeds

The postemergence herbicide formerly known as Liberty is taking on a more powerful personality. Get comfortable with the name Ignite because it's the herbicide you'll be pairing with the LibertyLink trait in corn, soybeans, cotton and canola.
Andy Hurst, Bayer CropScience product manager for Ignite and herbicide-tolerant traits, says Ignite 280SL is 40% more concentrated than the previous Liberty formulation. "We expect the grower cost per acre will be considerably lower,” Hurst adds. The name Ignite is familiar to cotton farmers, and the company decided to standardize the name usage.
LibertyLink soybeans still have a few regulatory hurdles to jump in the European Union, but import approvals for China came in early July and seed increases are in place for U.S. sales this fall and winter. The timing couldn't be better for farmers struggling with glyphosate- and ALS-resistant weed problems.
Ignite over the top of LibertyLink crops is the only nonselective alternative to glyphosate-tolerant system, and it has a unique mode of action with no documented weed resistance problems.
Ignite controls more than 120 grass and broadleaf weed species—including Palmer amaranth, cocklebur, lambsquarters, morningglory, waterhemp, velvetleaf and foxtail. The herbicide also works in preplant burndown programs before planting or crop emergence.
Hurst says registration work is being done to increase the seasonal use rate and the single use rate in soybeans. Currently corn and (pending registration) soybean farmers can apply 22 fl. oz. per acre up to a season maximum of 44 fl. oz. per acre.
University of Arkansas weed specialist Ken Smith sees the introduction as a lifeline for growers battling resistant weeds but cautions that timing and application volume might require a change-up in management for some growers. "If growers think it [LibertyLink] is a glyphosate-type system under another name, it will not be successful,” Smith says.
Ignite works best applied early when weeds are 3" to 4" tall. In soybeans, that may mean spraying as early as 10 days after emergence. At least 15 gal. of water per acre are required for thorough spray coverage.
The days of one-shot systems appear gone, too. Bayer is recommending complementary residual herbicides in addition to applications of Ignite. Growers are being encouraged to practice resistance management by using LibertyLink in rotation with glyphosate-tolerant crops.
Battle Bean Bandits
Late-season pests are the pits. Stink bugs, bean leaf beetle, Japanese beetle, grasshoppers—the list of bean buggers that vandalize crops during the reproductive stages keeps growing.
Soybean growers have a new tool in the form of Endigo insecticide. Syngenta Crop Protection
recently received a Section 3 registration on the insecticide. The product has already shown success in controlling cotton pests from full bloom through cutout and was cleared for use in potatoes earlier this year.
Endigo combines two modes of action (lambda-cyhalothrin and thiamethoxam) in a single application. In cotton, it has proved valuable as a rotational product to organophophsates and carbamates.
Sales of Endigo insecticide begin this year in the southern U.S. Syngenta has planned a limited launch for 2009, and a full launch is anticipated for 2010 to allow for adequate market supply.
Soy Secrets Revealed
A soybean yield contest entry of 154 bu. per acre has made Purdy, Mo., farmer Kip Cullers' advice as hot as the triple-digit temperatures during a recent field day that lured thousands of farmers.
"There is no reason we can't raise 300-bu. beans [in the future],” Cullers says. Although he won last year's contest with Pioneer 94M80, he's been testing the new Accelerated Yield Technology varieties and finds them "light years ahead.”
Cullers' beans typically receive two applications of BASF Headline fungicide—at the R1 or R2 growth stage and about two weeks later.
Cullers starts the season clean with residual herbicides and uses Optimize seed treatment to spur root development. He irrigates. He scouts almost daily to determine insecticide use. He uses poultry litter and foliar feeds micronutrients.
Cullers says his biggest challenge toward loftier yields is controlling plant height and improving stands.
Weeds Host SCN
Six winter annual weeds have been identified as alternative hosts to soybean cyst nematode (SCN). At the top of the list is the weed called purple deadnettle.
Purdue University Extension Weed Scientist Bill Johnson says a study in Indiana found that known SCN weed hosts were prevalent in 93% of the fields surveyed, indicating the possibility of a statewide increase in nematode populations due to winter annual weed hosts of SCN.
"Fields with these weed hosts may be increasing SCN population densities at a faster rate than fields without weed hosts,” Johnson says. Winter annual weeds have been increasing in fields over the past decade as growers have moved to more conservation-tillage practices. Less use of soil residual herbicides, which can be effective at suppressing late summer emergence of winter annuals, is also contributing.
Purple deadnettle and henbit are considered the strongest hosts. Field pennycress is considered a moderate host. Shepherd's-purse, small-flowered bittercress and common chickweed are weak hosts.
Purple deadnettle blooms purple between April and October. Infested fields can become a sea of purple. Henbit seedlings look almost identical to deadnettle.
If you have any of the six hosts, particularly the two strong hosts, you should be concerned with managing them and how they might impact soybean profitability by promoting SCN reproduction. Johnson says a late September or early October residual herbicide treatment appears to be the most promising option to eliminate fall SCN reproduction. "The fall herbicides would need to be sprayed as soon as the combine leaves the field,” he adds.
Controlling these weeds in the fall also reduces the importance of an early spring burndown application to prevent spring cyst formation. Here's the rub: Fall applications have been shown to promote earlier emergence and subsequent management problems of giant foxtail, common lambsquarters and common waterhemp.
"It's important for growers to understand the impact fall herbicide treatments will have on the summer annual weeds the following year,” Johnson says. "Use of fall residual herbicides should not be a substitute for using residual herbicides for summer annual weeds in the following year's crop.”
"Taps” for Alerts?
Tell us it isn't so … the entire early alert system developed to track soybean rust is scheduled to disappear after this growing season.
Since 2005, growers and their crop advisers have increasingly relied upon this national system, called the integrated pest management Pest Information Platform for Extension and Education (ipmPIPE). Originally built to advise growers about Asian soybean rust, it's been expanded to provide real-time information on soybean aphids, cucumber downey mildew, pests and diseases that affect legume crops, and the pecan nut casebearer.
The Web-based tracking system cost $3 million per year to develop and operate. The Risk Management Agency (RMA) has been providing operational funds—supplemented by soybean checkoff dollars and support from land-grant universities. The latest blow is the loss of RMA funding.
There is a request in the President's 2009 budget to increase funding that includes the alert system. Even if increased funding is included in the appropriations bill, the money may not be available for early season monitoring. USDA and other stakeholders are exploring possible stopgap measures. 

You can email Pam Smith at

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