Alternative Control Methods of Microdochium Patch - Interim Research Update

Clint Mattox, Alex Kowalewski and Brian McDonald
Department of Horticulture, Oregon State University

Microdochium nivale is the most important turfgrass disease in the Pacific Northwest (Vargas, 1994). Even though this disease can be observed year round, it is particularly devastating in the winter months. During this time of year, the turf is no longer actively growing, often leaving scars until the warmer spring temperatures return with the start of a new golf season. In order to combat this disease, golf course superintendents are required to make applications of fungicides, sometimes monthly from late fall to early spring.

In addition, M. nivale is particularly virulent on Poa annua turf, the predominant putting surface in the Pacific Northwest. Due to the recent trend for the public to demand more transparency in pesticide use and the fact that some areas of the world are limiting or are outright forbidding the use of pesticides on turf, the turfgrass maintenance industry is encouraged to find alternatives to pesticides.

Current research at Oregon State University is focusing on alternative control methods of Microdochium nivale. Potential methods currently being tested include reducing surface moisture, winter fertility practices, alternative products, and biocontrols. Preliminary Research Data (February to May 2013)

Preliminary trials were started in February 2013 at the OSU Lewis-Brown Farm Turfgrass Research Facility in order to pursue promising potential methods of alternative disease control. Preliminary research on Civitas, Sulfur and PK plus were promising and were included in a new trial started this autumn. However, the trials evaluating the effects of acidifier, copper soap, neem oil, charcoal, baking soda and borax were inconclusive along with the use of short-wave length (UV-C) radiation with the GreenZapyr; therefore these treatments were not included in the research initiated in the fall of 2013.

An additional trial focused on daily dew removal. In this trial, rolling significantly reduce disease occurrence (Table 1, Image 1,2 and 3), while the use of a buffalo blower with a sand-devil attachment, and a dew whip did not significantly affect disease activity.

Image 1: Double rolling performed daily from February 11th to April 9th

 Image 2: (Ladder Photo 04/22/13)

 Rolled Plot

 Untreated plot

 Image3: modified sand push-up green 6 months after construction

 Image 4: Initial Treatment Sept. 26th, 2013

 Research initiated in Fall 2013:

On September 26, 2013 four experiments were initiated at the OSU Lewis Brown Horticulture Farm. To facilitate this research a 3000 square foot annual bluegrass putting green was constructed in the spring of 2013 (Image 3). In order to give additional assurance as to the validity of this trial, a Microdochium nivale inoculate is being prepared using a pure culture and if necessary will be applied at the end of November.

Experiment One: The objective of this experiment is to evaluate the incidence of winter rolling, Civitas, sulfur and phosphite applications on Microdochium nivale in association with Poa annua putting greens. Treatments within this experiment include rolling, the mineral oil Civitas One applied at 6.0 oz/M, the phosphite product PK Plus applied at 6.0 oz/M, and sulfur applied at 0.25 lbs/M using the product Sulfur DF (Image 4). In addition to being tested independently, every possible combination of the three products is being evaluated. Rolling is performed five days a week and plots are treated with the products every two weeks.

Image 3: modified sand push-up green 6 months after construction. Image2: (Ladder Photo 04/22/13) Image 3 : 04/06/13 (Left rolled plot ) (Right Untreated plot) Image 5: Light Box readings used to asses percent green cover.

Experiment Two: The objective of this experiment is to quantify the effects of rolling applied in combination with biocontrol products on Microdochium nivale on Poa annua putting greens. Treatments included in this project are rolling, ReVive and ProVide from Earthfort, Experimental BW136N from Bioworks, and Rhapsody from Bayer. Rolling is performed five days a week and plots are treated every two weeks with the remaining products.

Experiments one and two are being replicated at the Washington State University Goss Research Farm, Puyallup, WA, experiments three and four and not replicated at WSU.

Experiment Three: The objective of the third experiment is to evaluate the effects of winter applications of nitrogen and iron sulfate on Microdochium nivale and turfgrass quality on a trafficked Poa annua putting green. Treatments in this project include varying rates of winter applied nitrogen (0 to 0.20 lbs N per 1,000 ft2 every other week) and iron sulfate (0 to 2.0 lbs Fe SO4 per 1,000 ft2 applied every other week). In order to quantify the recuperative potential of the different fertility regimes, these plots also receive golf shoe foot traffic comparable to the traffic received at the local Corvallis golf course, Trysting Tree Golf Club.

Experiment Four: The objective of the final experiment is to further explore the incidence of dew removal on Microdochium nivale on Poa annua putting greens. Factors in this trial include rolling, dew brush, a surfactant and a control.

Response Variables:
For all of these experiments (1-4), plots are being photographed and rated weekly accordingly to percent disease (0-100%), volumetric water content percentage, visual quality and color quality (1-9). Light box photos are taken monthly and are used to quantify percent green turf color (Image 5).

Image 5: Light Box readings used to assess percent green cover