EDMONTON – Producers shouldn’t hold their breath while waiting for new herbicides.
According to a herbicide researcher with Bayer CropScience, the new product pipeline has slimmed down.
“In 2003, 14 new herbicides were approved by the (U.S. Environmental Protection Agency) and 23 in the (European Union). It was about the same in 2004. In 2005 there was a drastic reduction – almost by 50 percent,” Hansjoerg Kraehmer of Frankfurt, Germany, told the recent FarmTech 2007 conference in Edmonton.
“For 2006 there was just one herbicide registered. In the future, we expect about eight new herbicides.”
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Kraehmer said weed control systems have changed in waves over the decades.
“In the ’50s and ’60s, there were growth hormones and photosynthesis inhibitors. They were followed by compounds like Treflan in the ’60s and ’70s. In the ’70s and ’80s, there were a vast number of new modes of actions, while the ’80s and ’90s were characterized by Group 2 inhibitors,” he said.
“Each mode of action allowed control of new weeds in new crops. The industry provided tools with lower rates per acre, plus lower and lower costs. Then, breeding technologies allowed for the introduction of herbicide tolerant systems in the ’90s, with a further decrease in herbicide costs. And the result – since the ’80s there is almost nothing new.”
Kraehmer said farmers now have several hundred active ingredients, with different modes of action, to provide selective control of weeds. However, this toolbox is changing, he added, and it will be difficult for new herbicides to enter the market. As well, new herbicide modes of action will be required to deal with herbicide resistant weeds.
“A study in Australia revealed that 21 percent of farmers with ryegrass resistance (to glyphosate) and 52 percent of farmers without resistance believe a new mode of action will be available within three to six years,” he said.
“This optimism, and the lack of perception for the real development and registration times, blocks the implementation of protection programs for the currently available herbicides.”
He had a specific message for farmers who don’t worry about herbicide resistance because they believe the chemical companies will come up with new herbicides: “I just want to make you aware that we will see consolidation and less companies involved in the herbicide business. The efforts for the development of new herbicides are huge, so it will not be easy.”
Kraehmer said one form of herbicide resistance can occur with a mutation of the target site in the weed. Another, metabolic resistance, occurs when weeds acquire the ability to degrade the herbicide.
Herbicides in groups 1, 2 and 8 are sprayed on about 20 million acres in Western Canada to control grassy weeds in cereal crops while about 40 million acres are covered with group 2, 4 and 6 herbicides to control broadleaf weeds.
“In wild oats, there’s recorded resistance on about four million acres. For dicot weeds, there are all kinds of resistance – Group 2, Group 4, Group 9 and others. The global situation shows more than 300 resistant biotypes within 182 species on over 270,000 fields,” he said.
“The first Group 2 resistance was observed in 1987 and today there are 93 weed species resistant to Group 2s in more than 30 countries. For Group 1, the first observations were in 1982 and now 35 grass weed species show resistance in more than 26 countries.”
While weed resistance management may become more complex, Kraehmer said within the industry there has been a shift from the classical agrochemical research into bioscience research.
Companies such as Bayer and Syngenta are still heavily involved in developing herbicides, while Monsanto is more a breeding company.
“Many companies have changed their strategic focus by shifting their research resources more into biotechnology activities,” he said.
“Between 1990 and 2005, there has been a steep decline in new patent applications in our industry.”
Is this the end of innovation and the beginning of weed problems on the farm?
“The number of new herbicides will decrease. Farmers will have to alternate weed control systems. Single pass applications with herbicides will become increasingly insufficient and combinations or sequential treatments will dominate herbicide regimes,” he said.
“The majority of corn and soybean varieties will carry the herbicide tolerant trait but stacked with input and increasingly output traits. It means you will get the herbicide tolerance trait almost for free.
The breeding companies will capture their value via quality traits, like high lysine content in corn or changed fat composition in oils. Some companies may even give away their herbicides for free and sell the variety.”
Kraehmer said that although there are fewer companies working on new herbicides, the need for new products isn’t going away.
“We need a global broad spectrum herbicide for rice. We need new herbicides for dicot crops. We need alternative solutions for Roundup Ready in soybeans. We need new, distinct mode of action herbicides for cereals. Highly flexible pre- and post-emergent herbicides for corn. One shot herbicides for all kinds of crops. Low dose, non-selective weed control tools for plantations, non-farmland and mixture options for the control of resistant weeds.”
In the quest to find new products and modes of action, companies have increased the number of products they test to find a winner.
“It took a few thousand in 1960 to find a new herbicide. In 1990, we had to screen 100,000 compounds to find one new herbicide. In 2000 it was 300,000 compounds and it will be half a million in 2010,” he said.
“We can easily screen one million compounds. We have screening robots that can test compounds with less than a milligram. We have already started synthesizing chemicals with robots. It takes a robot just one day to synthesize 10,000 compounds. We buy them from all over the world, exchange compounds, test natural products. But the limiting factor is the number of compounds.”
Kraehmer said a wide range of tests quickly narrow down the field.
“Let’s assume we test half a million compounds. After the first screening step, maybe 30 to 50,000 compounds are left and go into Phase 1. Out of these, maybe 10,000 go into Phase 2,” he said.
“From there on, we check soil adsorption, half life, leaching potential, carryover. In the field, we start with the first tox trials, like fish and algal toxicity.
The testing package becomes bigger the more advanced the compound is. In the second or third year in the field, we’re spending several million euros already just for the first characterization.”
Kraehmer said scientists use computer models, plants and insects to establish efficacy and safety levels of products.
They have one system that analyzes the shape of the receptor target three dimensionally. Then they try to fit potential chemicals into these receptors.
“We have an assay that analyzes the metabolism of a compound in a plant, so we know what the compound does in the plant. If we find special pathways in the plant change, we have a clue where the compound might inhibit.”
Kraehmer said it costs $150 to $300 million to develop a new molecule.
“We can only afford to develop our molecules in crops where we get our money back.”
