December 15, 2009
By John Bladon

The development of biological pest control products can be traced as far back as 400 BC in China. Today, these controls are essential parts of Integrated Pest Management practices.

Dr. Alan Watson, of McGill University and researcher of natural control agents for more than 25 years, identified Sclerotinia minor as a candidate for control of broad leafed weeds. Sclerotinia minor is a naturally occurring fungus in Canada and is the causal agent of several important crop diseases, including lettuce drop and Sclerotinia blight of peanut.

After an extensive review, the Pest Management Regulatory Agency registered Sclerotinia minor under the trade name Sarritor as a weed control agent. Sarritor is the Roman god of weeding and hoeing.

From the field in 2009

Like any new development, time is required for fine tuning the production and the application process in the field. Having been in the field in limited quantities in 2008, and in greater supply during 2009, the application of Sarritor to turfgrass is being slowly fine tuned as field experience accumulates.

“In my early years in the industry, we were able to take a much more program-based approach to lawn care. With the biological-based solutions like Sarritor, we have to synchronize our efforts with Mother Nature; one day might be perfect for certain types of applications and the next day less so. Based on this, our approach is far less schedule-based and much more reactionary. We have had to become highly adaptable throughout the growing season,” says Chris Lemcke, technical coordinator with Turf Operations Scarborough.

As the 2009 season continued, field reports that were based on several conditions, showed that temperature is a definitive catalyst for success in the field. Results show a dramatic effect on the success of Sarritor, with the pathogen having restricted effect during both high and low ends of the temperature scale. This year there was plenty of rain. Water is a key activator of the pathogen. But spring results didn’t show great success rates, because of the low air and soil temperatures.

Gavin Dawson, technical manager with GreenLawn – Toronto and past chair of LO’s lawn care sector group, told Horticulture Review that he found good results with Sarritor from late August through the second week of October. He also found that soil conditions played a big part in Sarritor’s results. “Over the past two springs, temperatures were cool and success was sporadic, while in the warmer soil conditions of late summer the product worked well.”

Cost is always a consideration to any program for lawn care operators. Current alternatives involve higher costs, compared to pesticide use before the Ontario ban in April. Initially thought to best perform with two 400-gram applications per 1,000 square feet per season, the latest field data suggests that on average, that success may be found at a rate of approximately two 250-gram applications per 1,000 square feet. This represents a 37 per cent reduction in cost. With the  2010 label amendments, that include the suppression of clover and plantain and the removal of the need to wear a respirator during the application process, the product will cost a bit less.

Production and handling

As a living organism, production and general handling of Sarritor is not without its complexities. Entrusted with managing production and distribution of the product is Canada’s Agrium Advanced Technologies.

“The product is easily the most intensive we have ever managed,” says Doug Hubble, sales and market manager with Agrium. “Although production has now ramped up to ensure an adequate supply, growing a living organism, cold storage requirements and managing inventory to ensure the product’s viability are a far more significant draw on our resources than with a traditional product line. We are constantly looking for ways to fine tune the product.”    

During production, the Sclerotinia minor pathogen is slowly grown and cultured on a barley granule under strict environmental conditions from temperature to humidity. To ensure uniform distribution and temperature levels during production, a centrifuge turns each batch. The barley’s purpose is two-fold. First, these 1.4 to 2 mm screened particles are intended to act as an a food source for the organism, an appetizer if you will, until such time as the organism can be introduced to the entrée, the broad leafed weed. The barley enables easy granular applications of the pathogen. Once production is completed, the product requires a vacuum seal to preserve the pathogen in an oxygen-free state. These sealed, 7.5 kg packages are transported and stored under chilled conditions.

Sarritor is based in Montreal, and was founded in 2004. The company’s website is
John R. Bladon attended Guelph and Cornell universities. He helped construct and grow two golf courses in Ontario and spent nine years as a golf course superintendent. He holds the title of IPM coordinator and is a technical representative with Agrium Advanced Technologies. He runs his own consulting and management firm.

Caption: Special backpack distributes sarritor.