Agrichemical companies continue to search for the ultimate, all-in-one herbicide to address farmers' weed-control needs.

The perfect herbicide, according to most growers, will require just one application prior to or at planting and will encompass all major broadleaf weeds and grasses at an affordable cost.

This silver-bullet herbicide doesn't exist yet. But many products come close. “What we have in the marketplace already is pretty phenomenal,” reports Bob Hartzler, extension weed scientist at Iowa State University. “I have a hard time picturing a huge advancement over what we have today.”

Even so, companies in the business of weed control continue to work on developing new options. Here is a look at the major agricultural chemical companies and what they are doing to develop new products.

Bearing the cost

Corporate consolidation has cut the number of agrichemical companies financially capable of developing new weed-control products. Most companies calculate it requires eight to 10 years and between $100 and $150 million to bring a new product to market. “If it doesn't make sense for us financially, then it ultimately doesn't make sense for the grower,” says Marty Mascianica, director of commercial development for BASF.

In many cases, developing a new product isn't financially viable because of a depressed marketplace. Although the amounts are somewhat nebulous, the Midwest corn market allows for a producer investment of up to $25/acre for an herbicide program. There is still enough financial opportunity in corn that companies are investing in research. Soybeans, however, are much more restrictive at about a $10/acre investment, based on the cost and use of Roundup.

“It's scary, because we aren't seeing new developments in soybeans like we used to,” says Aaron Hager, University of Illinois extension weed scientist. “It's just not financially attractive for companies because of Roundup's dominance.”

Development practices

Although the process of development varies, most companies employ a procedure called high-throughput screening to initially research and develop products. The process uses miniaturized trials to determine whether a chemical compound shows promise. Although this procedure does shorten the development process, researchers must still check a large number of compounds to find one weed-control jewel.

“Typically, we will evaluate 40,000 compounds before we find one good enough to develop,” Mascianica notes.

Syngenta uses an approach to development it calls rational design. The process requires selecting an active ingredient that offers a specific function or benefit, according to Chuck Foresman, Syngenta technical business manager. The company then designs an adjuvant delivery system that optimizes uptake and translocation of the herbicide in the weed. Such was the case with Touchdown, the company's glyphosate-based product.

“Rather than simply testing a variety of existing adjuvant packages, we looked at how the active ingredient traveled and acted within the plant,” Foresman explains. “Based on that understanding, we then developed a formulation that optimized that activity.”

Another product Syngenta introduced just this past June is Callisto. The product's active ingredient is mesotrione, which the company says offers a new mode of action (MOA) to control a wide spectrum of broadleaf weeds, including triazine- and ALS-resistant weeds.

Resistance issues

DuPont now looks for a new site of action (SOA) for weed control as opposed to an MOA, according to Raymond Forney, DuPont's corn and soybean discovery team leader. This should help minimize herbicide resistance. SOA refers to the specific process within a plant cell that's interrupted by the herbicide once it's applied and defines the exact location within the plant where the herbicide works. MOA is typically a broader term that refers to how the herbicide is applied and its overall effects on the weed.

Under the MOA herbicide classification, Roundup and Pursuit are placed in the same family, explains University of Illinois' Hager. However, classification by SOA places these two herbicides into distinctly different families.

To help you determine and better understand the chemical classes you're using in your fields, the University of Illinois has developed an extensive, color-coded classification system, based on 14 SOAs. To order the university's extension bulletin on SOAs, call 800/345-6087. The reference number for the bulletin is CS1, and the cost is $2. You can also review the color-coded classification systems at www.spectre.ag.uiuc.edu/cespubs/pest/articles/200101o.html.

Retired products

Based on work being conducted by the Environmental Protection Agency (EPA), some chemistries are being phased out of the marketplace. “We have to recognize that the government is raising the standards and a lot of compounds will be retired,” Mascianica says. “That will impact farmers, so we are looking at how we can provide replacement products.”

Forney adds, “There are $1.5 billion of triazine products in the marketplace as well as chloroacetamides that may need to be replaced.”

The EPA will reassess several compounds, including atrazine, benomyl, diazinon and carbaryl, by August 3, 2002. In addition, the EPA is committed to making cumulative risk reassessments by December 2001 for all 39 organophosphate products currently marketed. To review an outline of the pesticides to be reassessed, as well as the deadlines, go to www.epa.gov/pesticides.

Existing products

In recent years, companies have worked to improved existing products. They will continue to make products more concentrated so they will require less packaging and will be easier to use. Other improvements will include co-packs, premixes, and label expansions in new crops, and label refinements.

For example, BASF's new Ultra Blazer offers a response time that is faster than that of its predecessor. The company also is working on new formulations for Prowl, which will decrease the aromatic nature and improve equipment cleanup, according to Mascianica.

No company has succeeded in revitalizing an existing product quite like Monsanto with Roundup. The glyphosate-based product dominates the soybean market and is expected to do so for some time.

Mike Stern, Monsanto's director of technology for agricultural chemistry, says the company will continue to work with Roundup. Farmers can anticipate new formulations with improvements such as the improved rainfastness and ease of handling offered by the Ultra-Max formulation.

Hager acknowledges the product is efficient and affordable. “It's not uncommon to see three or four applications of Roundup in the same Illinois field in one year.” However, he encourages growers to rotate it out of their program in order to preserve its effectiveness. “If not, the system will break,” he says and points to reports of glyphosate-resistant mare's tail in the DelMarVa region as proof.

However, Stern says Monsanto is not concerned. “Monsanto investigates all reports of weed resistance,” he notes. “Weed resistance is extremely rare, given that Roundup has been on the market now for 25 years.”

Hartzler claims that if there were no barriers to widespread adoption of Roundup Ready corn, the pressure on glyphosate would increase. “What we need is more diversity in how we manage weeds,” he says. “Farmers need to use more crop rotations and when possible use more mechanical control.”