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Reinventing herbicides to benefit specialty crops

Reinventing herbicides to benefit specialty crops

Higher product development costs are causing chemical companies to reinvent older herbicides introduced up to 50 years ago. Chemical companies are developing new uses for older herbicides, plus generating new product formulations and application techniques. Formulation changes are largely in response to environmental safety concerns.

University of Arizona (UA) weed specialist Barry Tickes is a modern day Maytag appliance repairman of sorts.

The Maytag repairman featured in 1970s television commercials lacked enough work due to Maytag’s product claims of high dependability and infrequent appliance breakdowns.

Likewise, Tickes eagerly awaits new herbicide formulas for specialty crops, but the wait is long. New herbicide product introductions are rare for the specialty crop industry.

A key reason is the price to bring a pesticide to market. Costs to a chemical company to bring a pesticide from concept to market can take 10 years with a price tag of several hundred million dollars.

Due to these high costs, chemical companies are utilizing technology to reinvent older herbicides introduced up to 50 years ago. Companies and weed researchers are developing new uses for older herbicides, plus generating new product formulations and application techniques.

Tickes is a UA area Extension agent based at the Yuma Agricultural Center in Yuma, Ariz. He is busier than ever testing these new herbicide products to bring potential weed solutions to growers.

“Some older products have been around for 40 to 50 years. This is a testament to their value rather than just being old and obsolete,” Tickes told farmers, pest control advisers, and industry representatives at the 2011 Fall Desert Crops Workshop held in El Centro, Calif., in November.

The workshop was conducted by the University of California Cooperative Extension (UCCE), Imperial County, and by the UA Extension Service, Yuma County. Western Farm Press sponsored the workshop.

High product development costs also mean chemical companies are investing more existing pesticide research and research (R&D) dollars where the most revenue can be generated — in other words spending a larger chunk of the R&D budget on products for larger acreage crops.

Today, U.S. crop production includes about 86 million acres of field corn, 75 million acres of soybeans, 55 million acres of wheat, 21 million acres of alfalfa, and 9-plus million acres of cotton.

These gargantuan numbers dwarf specialty crop acreage which includes 151,000 acres of head lettuce and 37,000 acres each of spinach and cauliflower.

Today, 60-plus herbicides are registered for weed control in field corn and soybeans. More than 20 herbicides help prevent weeds in cotton. Fewer than 10 herbicides are registered for cole crops, lettuce, melons, and spinach.

“Companies are in business to develop new products and make money but they have to pay the bills,” Tickes explained. “There is a lot more money to be made in a corn crop with 90 million acres compared to 37,000 acres of spinach.”

Herbicide reliance

Despite fewer herbicides on the market, specialty crop growers rely heavily on herbicides. Produce buyers expect fields to be absent of weeds and damage from pests and diseases. Accordingly, growers utilize pesticides to grow near-perfect fields to ensure crop salability at a good price.

“One weed will not reduce the yield or quality of the crop, but one weed can change the attitude of a shipper about a particular field and grower,” Tickes said. “Disease- or insect-caused spots on spinach, for example, can result in a major price discount to the grower. Occasionally, a field with a very low level of injury is not harvested.”

Some herbicides applied on more traditional crops are now finding a good weed control fit in specialty crops.

For example, the herbicide Stinger (clopyralid), registered more than three decades old, was developed to control weeds in grain crops. In recent years, Stinger was approved for cole crops with positive results.

In one of Tickes’ herbicide field trials, Stinger was applied in broccoli to measure product effectiveness.

“Stinger has a good fit with excellent crop safety,” Tickes said. “Stinger did a remarkable job of saving the broccoli crop.”

Another example is the herbicide Sandia (halosulfuron), originally developed for nutsedge control in turf. Sandia was acquired by the Gowan Company in Yuma to develop a fit in specialty crops. Tickes’ test drove Sandia in a trial on the weed purslane in 10 different types of melons. Sandia performed well when the product was applied prior to weed emergence.

In Tickes’ spinach trial, the product Far-Go (trialate) did a good job controlling winter annual grasses.

In California, Tickes said UCCE farm advisors and weed specialists Richard Smith and Steve Fennimore have tested low rates of the herbicide Lorox applied as a pre-emergent in spinach to control annual broadleaf weeds.

“The overall crop safety is not real good, but they haven’t given up on it,” Tickes explained. “They believe they’ll find a rate that will be safe and effective.”

The herbicide Prowl, originally registered in the 1970s, is primarily used today on legumes, cotton, alfalfa, trees, and vines. Tickes says Prowl performed well on nettleleaf goosefoot and canarygrass in a broccoli trial.

Environmental safety concerns

In addition to new uses for older herbicides, changes in product formulations are occurring largely in response to environmental safety concerns. Many new formulations have shifted from previous powder and emulsifiable concentrate (EC) forms to water based and other more environmentally-safe formulations.

The powder herbicide Dacthal W 75 was difficult to work with since powders are difficult to measure and mix. Tickes says the liquid product Dacthal Flowable is easier and safer to use.

“Many emulsifiable concentrates (EC) and powders are disappearing and we’re getting more environmental and user-friendly formulations,” Tickes said. “Water-based formulations are definitely an improvement over powder-based formulations.”

GoalTender (oxyfluorfen) is another case where an EC was replaced with a water-based formulation. In cole crops and onions, the new formulation is safer to use than Goal 2XL.

New techniques in applying herbicides also are generating positive results. The product Kerb traditionally has been applied by ground and incorporated by furrow irrigation. Tickes says Kerb is more effective when applied through sprinklers. Sprinklers were not originally designed to apply pesticides.

“There is some spotty weed control and plant damage but overall sprinklers are an effective way to apply many herbicides,” Tickes explained.

Goal 2XL gets high marks when applied by sprinkler on onions.

“We found increased crop safety and improved weed control when applying Goal 2XL by sprinkler,” Tickes said. “It defies conventional wisdom but it works.”

Corporate sponsors of the Fall Desert Crops Workshop included: Platinum Level – BASF, Bayer CropScience, and Syngenta; Gold Level – Dow AgroSciences and Valent U.S.A.; Silver Level - FMC Corporation; and Bronze Sponsor – Westbridge Agricultural Products.

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