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New fusarium control on the horizon

Farmers who spray fungicides for fusarium may soon have a new biocontrol to consider

Fusarium head blight is a perennial problem for cereal growers across the Prairies. A fungal disease that can impact many small grain cereals including wheat, rye, barley and oats, fusarium is caused by infection by species of the fungal pathogen Fusarium, and can result in yield losses and reductions in grade and end-use quality. It can also produce mycotoxins such as vomitoxin (DON) that pose risks to human and animal consumers of grain products.

Fusarium management must take several forms to be effective. Techniques include seeding Fusarium-resistant varieties, mechanical strategies such as crop rotation, and applications of biopesticides and fungicides, says Xiben Wang, a pathologist at Agriculture and Agri-Food Canada’s Cereal Research Centre in Morden, Manitoba.

Other techniques, such as moldboard plowing, have shown mild reductions in disease incidence and severity, and DON accumulation.

At the Cereal Research Centre, Wang and his colleagues have a three-pronged approach to tackling the problem of fusarium.

  1. First, they are working on generating different high-throughput methods that will help them monitor predominant fusarium species in the field, as well as the toxins produced by these species.
  2. They are also collaborating with breeders to identify sources of resistance to fusarium.
  3. Finally, they are investigating the mechanism of pathogen infection on various crops, and finding key genes that are important for those pathogens.

Biological control

While most growers will be using fungicides to control fusarium in cereals for the next few years, a new and highly effective biocontrol is on the horizon.

Several years ago, while working at the Morden Cereal Research Centre, pathologist Allen Xue isolated Clonostachys rosea ACM941, a mycoparasite biopesticide, from a field pea plant. Xue demonstrated that Clonostachys rosea could be used effectively against both soil-borne and seed-borne pathogens on cereal crops. In 1999, AAFC patented ACM941. AAFC recently signed a 10-year licensing agreement with Kingston, Ontario-based company Adjuvants Plus Inc. to develop the technology.

Adjuvants Plus has said they are a couple of years away from registering and commercializing ACM941. AAFC is closely monitoring the technology’s development in its path toward regulatory approval through its Pesticide Risk Reduction Program.

Xue, now a research scientist in Plant Pathology at the Eastern Cereal and Oilseed Research Centre, has since been working on the identification and development of fusarium resistant germplasms and cereal varieties.

He has also been working with CLO-1, a product of ACM941, which is particularly effective against fusarium graminearum, which is caused by the pathogen Gibberella zeae.

“ACM941 is highly effective against G. zeae perithecial production, therefore reducing the initial inoculum,” he says. “It is moderately effective in controlling FHB, fusarium damaged kernels (FDK), and DON under the field epidemical environment, and moderately effective in controlling root rot and seedling blight when used as seed treatment (seedborne phase of FHB).”

Xue says these effects, while not significantly different, were demonstrably less than those shown by the recommended chemical fungicides, suggesting that ACM941 has potential for commercial use in an integrated FHB management system.

And this form of biological control, Xue says, “is better for the environment and for the organic production of crops.”

Wang says Clonostachys rosea ACM941 has been shown to be highly effective in reducing mycelial growth, spore germination and perithecial production in trials. “Its efficacy for the control of fusarium head blight has been demonstrated in several greenhouse and field trials supported by the Pest Management Centre,” he says.

“Studies have shown that strain ACM941 significantly reduced infected spikelets by 64 per cent and FDK by 65 per cent in greenhouse experiments when it was sprayed onto wheat heads two days prior to inoculation with Gibberella zeae,” he says.

Additionally, he says, under simulated disease epidemic conditions during 2005 to 2007, strain ACM941 reduced the FHB index by 58 per cent, infected spikelets by 46 per cent, FDK by 49 per cent, and DON in kernels by 21 per cent.

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Julienne Isaacs

Julienne Isaacs is a Winnipeg-based freelance writer and editor. Contact her at [email protected]

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