Agrochemical firms combine chemistry and biology to fend off pests and boost plant health

Early every spring, farmers drop tasty, expensive seeds into furrows of damp, cold soil. Hungry insects and famished fungi await this gift from above, often chowing down before the seeds even have a chance to germinate.

When seeds get eaten, or tiny sprouts wither from fungal invasion, the promise of today’s pricey genetic traits goes unfulfilled. To wait until the climate is more forgiving means a shorter growing season, which in colder climates can be risky.

"Farmers get a huge yield advantage when planting early. There may be snow on April 6, but then you see tractors on April 10,” remarks Palle Pedersen, seed care technical manager at the crop protection firm Syngenta. As the former soybean agronomist for the State of Iowa, Pedersen has had a clear vantage point for observing the development of new technologies that protect seeds.

Although genetic modification and advanced hybridization tend to get the glory, today’s seeds owe much of their improved survival during germination to specialty seed treatments, Pedersen says. “We have good cold tolerance built into the germplasm, but seed treatments that protect the seed in the cold and damp give you an even higher stand and yield,” he observes.

Seed treatments are the result of collaboration among chemists, plant scientists, and agronomists. Together, these researchers come up with tailored combinations of fungicides, insecticides, and nematicides that are mixed with a polymer coating to surround and protect each seed.

Agrochemical seed treatments, such as those sold by Syngenta, have become the norm in the seed business, and new products continue to emerge from the development pipeline. But now they are being joined by biological approaches. Proponents of biological treatments claim that microorganisms give plants longer-lasting allies against pests and encourage earlier, more vigorous growth.

The biological approach is still at an early stage, Pedersen cautions. “If you go through every paper that’s been published, it works very well in greenhouses and growth chambers—in controlled conditions. In the real world, you get inconsistent results.”

On the other hand, every major seed firm is investigating biological approaches, Syngenta included. Bayer CropScience, Monsanto, and BASF are also engaged in the hunt for next-generation seed treatments.

Microbes are poised to take a big bite out of the market, according to Brad Griffith, Monsanto’s global seed treatment lead. The oldest biological seed treatments are inoculant microbes added to soybeans to improve nitrogen fixation. Griffith forecasts that a new generation of products will push biologics from one-fifth of the seed treatment market today to one-third by 2015. Now, to work alongside its next-generation gene traits, Griffith says, Monsanto is “looking forward to yield and stress resistance—for example, for drought—in new seed treatments.”

Microbes are poised to take a big bite out of the market.

Seed treatments in general have grown in popularity with farmers over the past decade, and adoption has picked up speed in the past two years. The main driver has been high prices for today’s genetically modified seeds. The sales manager of a seed supplier in the upper Midwest, who asked not to be identified because he is not supposed to reveal retail seed prices, says farmers pay about $104 per acre for Monsanto and Dow Chemical’s new Genuity SmartStax corn, which includes about $6.00 worth of seed treatment technology. “They’ll buy as much insurance as they can,” he says.

The global seed treatment market has reached $1.5 billion annually and is growing at a rate of 10 to 12% per year, according to a report by Laurence Alexander, chemicals analyst at the investment firm Jefferies & Co. “As more traits are stacked and integrated into seeds, seed treatments can provide a cost-efficient way for farmers to protect their investment,” Alexander says. He points out that the products appeal to farmers worldwide: Only 25% of the market is in the U.S.

The report names Germany’s Bayer CropScience as the world leader in seed treatment technologies, with about $820 million in annual sales. The company both treats its own seeds and sells treatments to other companies.

Seed treatments include active ingredients picked from a long list of possibilities. The actives target particular crops, specific pests or diseases, and even different geographic regions. Tiny amounts of the active compounds are mixed with inactive coatings such as vinyl polymers and mineral fillers such as aluminum and calcium salts. Finally, a pigment is added to distinguish each brand of seed and prevent treated seeds from entering the food or feed supply chain.

Bayer’s two largest treatment products are based on neonicotinoid insecticides. The biggest seller, clothianidin, marketed as Poncho and other names, can be put on canola, cereal, corn, sunflower, and sugar beet seeds. It helps protect seeds against a host of early-season pests, as well as soil and leaf pests such as aphids, beet leaf miners, black cutworms, corn rootworms, grubs, and wireworms.

Clothianidin and its sister product, im¬id¬acloprid, marketed as Gaucho and other names, are chemical insecticides similar to those used in soil and foliar applications. But, Bayer spokesman Utz Klages says, applying insecticides and fungicides earlier on seeds rather than later on leaves or fields is the most advanced and effective mode of delivery. Only a small amount of the chemicals needs to be applied, and very little comes in contact with the soil.

However, clothianidin and imidacloprid seed treatments came under scrutiny in Europe starting in the late 1990s as possible causes of honeybee colony collapse (C&EN, June 18, 2007, page 48). Most studies showed that the residue levels bees came into contact with were too low to be toxic, and in March 2010, the European Union put both insecticides, as well as a newer member of the family, thiamethoxam, on its list of allowable chemicals for seed treatments. Still, the EU amended the directive to say “accidental releases of those active substances recently reported by several member states have resulted in substantial losses of honey bee colonies.”
Neonicotinoids work by disrupting the nicotinic acetylcholine receptor of an insect’s nerve cells. They have low toxicity to mammals. When used as a seed treatment, they are taken up by the sprouting roots of the plant and protect the plant from chewing and sucking insects.

Although its seed treatment business is primarily chemical, Bayer started last year to commercialize what it calls biocontrol agents. It acquired two technologies from AgroGreen, an Israeli biopesticide firm that had developed a soil treatment based on the soil bacterium Bacillus firmus to control nematodes in some vegetable and orchard crops. AgroGreen also makes a foliar biofungicide from Metschnikowia frucitcola, a strain of yeast isolated from grapes grown in Israel.

Next year, Bayer will launch the nematicide as a seed treatment for corn, soybeans, and cotton under the trade name Votivo. For seeds, “Votivo provides enough protection to withstand early-season nematode feeding, when damage potential is highest,” Klages says. In September, Bayer gave Monsanto the right to commercialize a seed treatment that combines Votivo with clothianidin.

For its part, Monsanto got into seed treatments in a serious way in 2007, when it launched a seed treatment platform called Acceleron. The company sources all of its active ingredients from third parties, including Bayer and Syngenta, Griffith says. “The simplest way to think about the benefits Monsanto has in this space is that we have the opportunity to look at the performance of these chemistries and potential biological products on top of our genes and traits before anyone else can see them,” he says.

The size and sophistication of Monsanto’s test fields can have an especially big impact when the seed firm works with smaller biotech companies such as AgraQuest.

The two companies recently signed a three-year deal to develop seed treatments from AgraQuest’s pipeline of biopesticides for Monsanto’s crops and vegetables.

"They are challenging studies to run, because you need 30 independent sites with multiple replications at each site. Managing the studies is very difficult,” says Jonathan Margolis, senior vice president of R&D at AgraQuest. “With Monsanto, we can look at performance in many different geographies.”

Seed treatments made with AgraQuest’s Serenade are already undergoing field trials with several seed and seed treatment companies. Based on a patented strain of B. subtilis, Serenade was designed to protect against fungal and bacterial diseases. The microbe secretes several lipopeptides that punch holes in the membranes of fungal cell walls.

Margolis explains that AgraQuest works with university research labs to identify and commercialize beneficial microbes. The excitement surrounding biological agents is justified, he contends. By putting a beneficial microbe on a seed, “you can have colonization and proliferation in the soil. You get the microbe growing and coating the roots with protection activity into the late season, months after planting.” In contrast, he says, chemical treatments last for weeks at most, after which they are diluted or break down as the plant grows.

The soil zone around the roots where the microbes do their work is called the rhizosphere. In this millimeters-thick region, the bacteria in Serenade form a barrier that protects the plant from diseases, according to AgraQuest. The bacteria also emit 2,3-butanediol, a phytostimulator said to promote plant growth. Serenade is one of what AgraQuest hopes will be a family of biologically derived products that make plants more resistant to abiotic stress. “There are a whole variety of other Bacillus strains with other properties,” Margolis says.

From Monsanto’s perspective, biological active ingredients will be used mainly with chemical treatments. However, the two do not play together nicely. “The biologicals create a different level of complexity in treatment because you don’t want to add a chemical that kills the biological agent,” warns Tom Adams, chemistry technology lead at Monsanto.

Another company poised to benefit from the uptake of beneficial microbes is industrial enzyme maker Novozymes. The company makes nitrogen-fixing inoculants for leguminous crops and now has a new seed treatment, called JumpStart, that helps plants access phosphates from the soil or from fertilizers.

According to Trevor Thiessen, president of Novozymes’ BioAg business, a government researcher in Alberta who was seeking a way to make phosphate fertilizers more available to plants discovered the JumpStart soil fungus. Phosphates aren’t especially expensive, Thiessen explains, but they don’t work very well. “Farmers put a lot of phosphate in the soil, where 70 to 90% of it becomes tied up in the soil and not taken up by plant roots,” he says. JumpStart colonizes the rhizosphere, where it releases acids that convert mineral phosphates into a more plant-digestible form.

Novozymes’ next big project is to develop a nitrogen-fixing microbe for nonleguminous plants. The company is in its first year of testing a product on Brazilian sugarcane fields. “Our ambition is not to equal the nitrogen fixation of a pea plant, for example, the way nature has designed for 100% fixation,” Thiessen says. “But if we could get 20% fixation for corn or wheat and let regular nitrogen fertilizer do the balance, that would be a neat innovation.”

Thiessen readily acknowledges the criticism that biological seed treatments are sensitive to variables such as pH, moisture, and temperature. “It’s a valid statement,” he says. “Microbes are similar to you and me in that they are a living organism. In a cold climate we may have to put on some protective coats or wear winter boots.”

Nonetheless, Monsanto’s Adams says he’s looking to see what biology can do for his firm’s seeds. For example, there’s still more to do to combat fungal diseases, Adams contends. “Can you extend the control of fungi beyond the first weeks? That’s not easy to do, or the chemical companies would have done it already.”

But more than pest control is at stake. “One reason to be interested in biological treatment is the claim that it can really stimulate plant growth,” Adams says. “We would like to move seed treatments well beyond where they are now—just insurance on the seed—to increase the value of the plant on the other end.”