A backyard gardener plucking cabbage loopers off broccoli plants gets a glimmer of how devastating pests can be to a crop. For large scale agricultural producers, pest control is crucial. A field ravaged by insects or inundated with weeds can have a huge impact on the producer’s bottom line. For decades, chemical pesticides have offered reliable control for conventional agriculture, but it came with a price: as effective as they were, some of those chemicals pesticides caused problems: ozone depletion, tropospheric pollution with volatile organic compounds, contamination of waterways and human health issues.

The pesticides and fumigants were not selective either, often killing beneficial insects and microorganisms along with the pests. Modern synthetic pesticides are much safer, but alternatives are still needed to replace pesticides that are damaging to the environment or dangerous to producers. Bio-based pesticides and fumigants offer new, safer tools to fight old pests. These products can even offer protection for organic acres, where synthetic pesticides are not an option.

At the 4th International Biofumigation & Biopesticides Symposium hosted by Ag-West Bio in Saskatoon this fall, researchers and delegates from 13 countries discussed novel ideas and new products for controlling agricultural pests and pathogens. The scope of the meeting was broadened this year to include biopesticides and technology commercialization, while in past years the program focused on biofumigation research. Ian Porter, Principal Research Scientist with the Department of Primary Industries in Victoria, Australia, says the Biofumigation & Biopesticides meeting is essential to determine what’s sustainable and what products will be developed for future use. Jarrod Leland, a researcher with Novozymes BioAg, says he appreciated the expanded program. “It was nice to interact with academia and industry and have very practical discussions about what it takes to enter the market.

It’s important in the academic world to understand what questions need to be answered as we bring products to market. At the same time, companies don’t have unlimited resources, so we do need to team up with academia and have them help us answer our questions.”

Out with the old…

One topic covered in depth at the Symposium is the effort to find alternatives to methyl bromide, a soil fumigant introduced as a pesticide in 1932 and widely used, primarily for control of nematodes, fungi, and weeds in high value crops, such as strawberries1. Methyl bromide (or bromomethane – CH3BR) was listed as a major ozone depleting gas in 1992 under the Copenhagen Amendment of the Montreal Protocol on Substances That Deplete the Ozone Layer2. A strategy was developed to phase it out for agricultural use in developed countries by 2005 and developing countries by 2015. However, because methyl bromide had been used for 60 years so successfully – mainly for preplant fumigation to reduce diseases and improve yields- a separate process under the Montreal Protocol was created to allow ‘critical use exemptions’ for methyl bromide. These exemptions were only allowed if countries could prove that there were no economically or technically feasible alternatives and have fallen from 18,500t in 2005 to 700t in 2013. At its peak approximately 53,000 tonnes of methyl bromide was used for soil fumigation in developed countries and 3,000t for treatment of commodities.

Developing countries have reduced use by 75 per cent to around 3,500t. The largest use now is for Quarantine and Pre-shipment Uses (10,000t) which is not yet controlled under the Montreal Protocol. The United Nations Methyl Bromide Technical Options Committee under the Montreal Protocol is the group that analyses submissions for critical use exemptions. Ian Porter is Co-Chair of the Committee. He calls the Montreal Protocol “the most successful international protocol ever,” with every country in the world a signatory for the Protocol. The success, he says, is because it was science-based and fair, with developed countries contributing to a multi-lateral fund that pays developing countries to discontinue methyl bromide use. Thanks to the Protocol, 88 to 90 per cent of ozone depleting gasses have already been phased out, with a major impact of reduction in ozone depletion and signs of recovery of the ozone layer which will continue for much of this century, resulting in less UV radiation reaching earth, with benefits for human health (including fewer skin cancers and cataracts); healthier ecosystems; and reduced weathering of building products.

In with the new…

Yaacov Katan, a Professor Emeritus of Plant Pathology at the Hebrew University in Rehovot, Israel, says it’s important to use the methyl bromide crisis as a lesson. We need to avoid becoming dependent on a single product again by increasing the arsenal of tools available, developing integrated pest management programs and putting an emphasis on biologically-based methods which improve soil and crop health. Alternatives to methyl bromide discussed at the Symposium included Brassica-based biofumigants as well as non-fumigant methods for weed and disease management, such as anaerobic soil disinfection, an interesting approach that uses blackstrap molasses, combined with soil saturation and solarisation to enhance populations of a beneficial fungus (Trichoderma spp.) in the soil. Some green manures (cover crops grown to add nutrients and organic matter to soil) also have biocidal properties.

The use of steam to kill soil pathogens in special circumstances was also explored. According to plenary speaker Frank Sances, founder and research director of Pacific Ag Group, a U.S. organization that conducts contract crop research, the nascent industry is “finally in the right place at the right time.” It seems that many of the attendees agreed with his sentiment. After many years of research, the pieces are falling into place: public demand for safer pesticides, government support for the development of alternatives, and industry drive to fill the niche markets that are being created by new legislation.

John Kirkegaard with CSIRO (Australia’s national science agency) is the International Chair of the Biofumigation & Biopesticide committee. He says a market niche has just opened up. “As more money is pumped into research and development, I think you’ll see more and more products come down the pipeline to reach the market.” Pamela Marrone, founder and CEO of California-based Marrone BioInnovations, believes there is “wide open opportunity for discovery” in using microbes for pest control.

“You can find a microbe to do just about anything, if you look,” she says. Marrone notes that only 11 per cent of pesticides are derived from natural products, while 50 per cent of human drugs come from nature. Formulation is the key, she says; for products to be commercially successful they must be effective and easy to use.

Battles in miniature

Karen Bailey, a research scientist at Agriculture and Agri-Food Canada’s (AAFC) Saskatoon Research Centre spoke about her work developing a naturally occurring soil fungus, Phoma macrastoma, for control of broadleaf weeds, including dandelion, in turf and cereals. The fungus enters the plant through the roots and produces a phytotoxin which causes the plant to stop photosynthesis, turn white and die. Bailey says extensive studies show the fungus only travels eight centimetres into the soil and less than 30 centimetres laterally, making it very safe for yard use. After four months, there is no detectable trace of the fungus, so crops that would be susceptible can be grown again after this time. The technology is currently registered in Canada and should be on the market by 2014.

Another fungus is the base for an insecticide developed by Novozymes BioAg. Researcher Jarrod Leland says Metarhizium anisopliae occurs in soils worldwide. It enters an insect’s body through the cuticle, circulates in the blood system and kills it. The product developed by Novozymes works on vine weevils and thrips, whiteflies mites and ticks. Currently, a granular version is on the shelves and sold mostly in Europe. The product is also registered in the U.S. and Canada. It is used as a replacement for chemical pesticides in high-value crops and is especially desirable because of growing resistance to chemical insecticides. Leland says because the growers they work with use beneficial insects as part of their control system, it is critical that their product does not harm them.

Denise Manker is a researcher with California-based AgraQuest, Inc. Manker says the company was set up in the 1990s to search for natural pest control solutions for agriculture. For seven years, the company screened for naturally occurring microbes that had an effect on pathogens and pests of agriculture crops. The most effective microbes were then developed into commercial products. AgraQuest’s fungicide SERENADE® SOIL, based on the bacteria Bacillus subtilis, protects plants using several modes of action. The bacillus produces metabolites, which directly kill pathogens, and colonizes the root zone, growing along with the root and acting like armour. The bacillus also enhances the plant’s immune system by priming a systemic acquired resistance response. Unlike chemical fumigants that kill everything in the soil, SERENADE® SOIL interacts specifically with the pathogens and cooperatively with beneficial microorganisms.

A paradigm shift

Moving to bio-based solutions may require a paradigm shift. Porter believes we’ve become accustomed to an unsustainable level of pest control offered by chemical pesticides – with yields two or three-fold what they were before World War II; “higher than what we really should be attaining if in order to be sustainable.” Kirkegaard says although many years of research have been conducted, the commercial industry is just getting started. He believes that, used in combination with other control strategies – or sometimes alone, bio-based products can be as effective as the more toxic chemical controls they are meant to replace. “They have to be effective, or farmers won’t use them. But increasingly,” he says Kirkegaard, “they have to be safe, or farmers won’t use them and consumers will have concerns about their use.”

Click here to see more video interviews from the 2011 Biofumigation & Biopesticides Symposium.

  1. http://npic.orst.edu/factsheets/MBgen.pdf
  2. http://www.theozonehole.com/montreal.htm


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