Control of Grey Snow Mould with Typhula phacorrhiza

Summary of 1998-1999 Results

Dr. Tom Hsiang, Department of Environmental Biology

University of Guelph, Ontario N1G 2W1

For the past six years, we have been working on a biological control system for snow mold diseases. We started out in 1994 looking for better strains of a fungus that could suppress diseases caused by the fungi Typhula ishikariensis and Typhula incarnata. Dr. Lee Burpee who used to be at Guelph and Dr. Now Matsumoto in Japan had found that a fungus named T. phacorrhiza could inhibit grey snow mold disease. We collected strains of Typhula phacorrhiza from corn fields all over southern Ontario. By 1997 we had identified five strains out of several hundred that work as well at suppressing grey snow mold as conventional fungicides. This work during the first three years was supported by the Canadian Turfgrass Research Foundation with matching funding from the Ontario Ministry of Education and Training.

In 1998, we started on a new phase of this research with funding from the Canadian Turfgrass Research Foundation. This money was matched by Nu-Gro Corporation who were interested in commercialization of this product and the rights to distribute it. Then funding from both organizations was matched by a federal program, the Natural Sciences and Engineering Research Council. As a result of the increased funding, we were able to expand the study to sites across Canada starting in 1998. Although T. phacorrhiza can be found in abundance in corn fields after spring snow melt, the large majority of these isolates have little or no effect against grey snow mold. Our continuing work is to develop ways of growing and formulating the inoculum of a select isolate of T. phacorrhiza that is antagonistic to grey snow mold and possibly pink snow mold. We are hoping for a product within 2 years formulated as a granular that can be applied with conventional equipment.

1998-1999 Results (Highlights)

Major achievements of this past year of research include:

Residual Efficacy of Typhula phacorrhiza (TP) on creeping bentgrass: After 5 years of study, we found that a single application of TP can suppress grey snow mould disease for the subsequent 3 years. This work has been accepted for publication in a scientific journal.

Suppression of pink snow mould by TP: In Ontario trials near Barrie (natural snow mould inoculum) and Guelph (pathogen inoculated), pink snow mould was suppressed by isolate TP94671. This was the most exciting finding in 1999, and we have established trials across the country to test this again in 1999-2000.

Persistence of a select genotype of TP in a corn field over a winter: An isolate of TP applied to corn stalks prior to snowfall can persist as the same genotype through the winter and produce abundant sclerotia by snow melt. This critical for a commercial product since we must show that it will remain stable through a winter.

Production of sclerotia in harvested vs. unharvested corn fields: More sclerotia were found in unharvested compared to harvested corn plots that had been inoculated the previous fall with TP94671. This means that the TP inoculum could be grown in unharvested corn fields to yield more inoculum.

TP trials across Canada: In 1998, we established trials in Ontario (Barrie, Guelph, Manotick), Quebec (Montreal), Saskatchewan and British Columbia (Golden). Winter injury was so severe on some of these sites that they could not be properly rated. For trials at Barrie and Guelph, the TP biocontrol treatment worked as well as the best fungicide treatment. In 1999, we established fully replicated trials at Golden, Olds, Guelph and Kemptville, with smaller trials at Barrie, Invermere and near Orangeville.

Production of sclerotia of TP on different corn cultivars: There was a two-fold difference in sclerotial production between the lowest and highest numbers on different corn cultivars. Particular cultivars can be chosen for increased sclerotial production.

Fungicide sensitivity of disease-suppressive isolates of Typhula phacorrhiza: In an integrated disease management program, fungicides may also need to be used either before or along with TP. The results showed that although TP is sensitive to all the fungicides used for snow mould control, the differences in sensitivity between it and snow mould pathogens may permit fungicides such as Arrest to be used for T. incarnata-incited grey snow mould, or Tersan for pink snow mould. However, since TP shows efficacy against both major snow moulds, fungicide applications for snow mould control may be unnecessary and our target is the use of TP alone.

Viability of TP in processed corn residue: corn residue infested with sclerotia and mycelium of TP was collected after snow melt and ground using hammer mills. We were able to re-isolate TP from the majority of both fine and coarse fragments after grinding. This is important if we use a corn-based formulation and need to process the inoculum into pellets or granules.

Registration Package for PMRA (Pest Management Regulatory Agency): The package is in its third round and we expect to present it to PMRA before the end of 1999.