Turf Line News

September 2012

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TURFGRASS RESEARCH BY K.L. BAILEY (AGRICULTURE & AGRI-FOOD CANADA, SASKATOON) AND S. FALK (THE SCOTTS COMPANY, MARYSVILLE, OH) AN UPDATE ON THE NEW TURFGRASS BIOHERBICIDE: PHOMA MACROSTOMA Phoma macrostoma is a fungus that is being developed as a bioherbicide to control broadleaved weeds like dandelion, Canada thistle, and clover. The fungus naturally infects Canada thistle (far right photo), causing plants to turn white. Without chlorophyll, the plants die. When applied as a granule to soil before weed emergence, the fungus causes the emerging thistles to come up white (top left photo). The fungus has been isolated and purified from plants growing in Saskatchewan and other provinces by AAFC scientists (top left photo). For several years, the fungus Phoma macrostoma has undergone extensive evaluation by Agriculture & Agri-Food conditional registration for Phoma macrostoma to be used domestically and commercially for control and/or suppression of weeds such as dandelion, scentless chamomile, English daisy, white clover, black medic, Canada thistle, chickweed, broadleaf plantain, and ragweed. The bioherbicide may be used safely on a variety of turf types such as Kentucky bluegrass, bent grass, perennial or annual ryegrasses, fescues, bromegrasses, timothy, and Bermuda grass. The fungus is formulated into granules which may be applied to either newly- seeded or well-established lawns from a ready-to-use applicator for spot When broadcast on turf, Phoma macrostoma reduces the broadleaved weed species, but does not harm the grass. Once in the soil, Phoma macrostoma enters the roots and then the fungus (red) grows towards the plant's vascular system (green), as shown by microscopic imaging. Municipal and provincial bans of conventional herbicides in urban centres and the appeal of organic food have created a demand for alternative weed control strategies. Our team has developed a solid state fermentation process and formulated the product as a granule. Phoma macrostoma can be used for broadleaved weed control in... Urban Areas/Turfgrass A DNA-specific marker for Phoma macrostoma showed that the fungus can be found in weed roots and in the 1-8 cm deep soil profile. However, the fungus was not detected in the 30 and 60 cm soil margins beyond the treated area. Phoma macrostoma did not move from the site of placement, thus reducing the risk to nontarget plants and organisms. Canada and The Scotts Company to see if a bioherbicide could be developed to control broadleaved weeds in turfgrass. In 2009, the summer issue of Sports Turf Manager reported on its discovery as a potential bioherbicide, and some of the research demonstrating its efficacy and crop safety. In June of 2011, the Pest Management Regulatory Agency approved a The fungus was detected in soil at 1, 2, and 4 months after application, but it was not detected after 12 months. The population of Phoma macrostoma declined with time showing that it was not competitive with other naturally-occurring soil microorganisms and fauna. 40 WESTERN CANADA TURFGRASS ASSOCIATION treatments or by broadcasting the granules as either pre-emergent or post-emergent applications. The product may be applied anytime from spring through fall, but it works best when the mean day time air temperature is hovering above 20°C (15-30°C range) and the soil is relatively moist. The product does not need to be "watered- in" but some precipitation or irrigation (up to 1-3 inches) within 24-72 hours after application would be beneficial particularly if the soil is not friable or moist. Continuing research has expanded our knowledge of how the Agriculture/Cereals bioherbicide will perform in the field. Studies have shown that extreme moisture events around application will reduce the level of weed control attained, especially on sandy soils. macrostoma will not harm susceptible crops like field pea if grown one year after application as the fungus is not persistent in the soil. Phoma bioherbicide may be applied at the same time as commercial granular fertilizers which may result in a 10- 15% enhancement in weed control. Currently, Phoma macrostoma is undergoing scale-up development to be able to efficiently produce commercial quantities and so a commercial launch is still a few years away. Additional Reading : Zhou, L., Bailey, K.L., and Derby, J. 2004. Plant colonization and environmental fate of the biocontrol fungus, Phoma macrostoma. Biological Control 20: 634-644. Bailey, K.L., Pitt, W.M., Derby, J., Walter, S., and Taylor, W. 2010. Efficacy of Phoma macrostoma a bioherbicide for control of dandelion (Taraxacum officinale) following simulated rainfall conditions. The Americas Journal of Plant Science & Biotechnology 4 (Special Issue 2): 35-42. Bailey, K.L., Pitt, W.M., Falk, S., and Derby, J. 2011. The effects of Phoma macrostoma on nontarget plant and target weeds species. Biological Control 58 (3): 379-386. Bailey, K.L. and Falk, S. 2011. Turning research on microbial bioherbicides into commercial products – A Phoma story. Pest Technology 5 (Special Issue 1): 73- 79. Agro-Forestry/Evergreens

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