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Super Science: A year of research in review

Tropical signalgrass — bringing an old foe to its knees?

By Bert McCarty, Ph.D.

Much research and product introduction have a problematic weed finally on the back burner.

  • Tropical signalgrass is a warm-season perennial grass that spreads by stolons or seed and occurs when soil temperatures reach 77 degrees F (25 degrees C).
  • Herbicide application timing is improved with a careful mapping of infested areas and recording spray applications.
  • Fall herbicide applications are most effective, though, in many situations, interfere with fall overseeding or do not allow sufficient time for turf recovery before winter.
  • All products and combinations will require multiple applications to achieve adequate control.
  • To lengthen control, include a preemergence herbicide such as indaziflam, oxadiazon or prodiamine.

BMPs for anthracnose on annual bluegrass putting greens

By Bruce Clarke, Ph.D., James Murphy, Ph.D., and John Inguagiato, Ph.D.

Researchers at Rutgers University developed best management practices for anthracnose (Photo 4) while busting myths from the past.

<strong>Photo 4</strong> Researchers at Rutgers University have developed best management practices for anthracnose. In this photo, leaves have turned yellow to brown and are sprinkled with black spore-bearing structures. (Photo: James Hempfling)

Photo 4 Researchers at Rutgers University have developed best management practices for anthracnose. In this photo, leaves have turned yellow to brown and are sprinkled with black spore-bearing structures. (Photo: James Hempfling)

  • Plant nutrient deficiencies, ultralow mowing and excessively wet or dry irrigation programs are critical stress factors that significantly increase the risk of severe damage from anthracnose.
  • Avoiding deficiencies in nitrogen and potassium is critical to reducing anthracnose severity.
  • The combination of three BMPs (increased nitrogen, higher mowing and greater topdressing) can suppress anthracnose to acceptable levels without the use of fungicides.
  • At lower mowing heights (<0.125 inch) to improve green speed, use higher nitrogen and routine topdressing practices to reduce anthracnose severity.
  • Routine topdressing is most beneficial under conditions of lower mowing and lower nitrogen fertilization.
  • Fungicide efficacy is improved, and a reduction in fungicide inputs (as much as 80 percent) is feasible with the adoption of BMPs.
  • Following these BMPs with early-curative sprays can result in significant reductions in fungicide inputs and excellent disease control.

Snow mold strikes again

By Paul Koch, Ph.D.

Snow mold pressure was very high across Wisconsin and the Upper Midwest (Figure 2) showing minor environmental changes in a small area can lead to large changes in disease development.

<strong>Figure 2</strong> Average monthly snowfall in Madison, Wis., has increased over the last 10 years in January and February but has fallen significantly in November and December. December is usually a critical time for snow mold development. The figure is taken from the website https://news.wisc.edu/new-weather-normals-show-how-madisons-climate-has-changed-over-40-years/.

Figure 2 Average monthly snowfall in Madison, Wis., has increased over the last 10 years in January and February but has fallen significantly in November and December. December is usually a critical time for snow mold development. The figure is taken from the website https://news.wisc.edu/new-weather-normals-show-how-madisons-climate-has-changed-over-40-years/.

  • Snow mold breakthrough on fungicide-treated turf was very rare, suggesting that snow mold applications made in October and November knocked back the fungal population.
  • We see increases in snow mold control when fungicide applications are made at heating degree day accumulations right around 100 (i.e., from July 1 of each year, record how much below 50 degrees F the average daily temperature was during the day).
  • We have not found alternative methods (e.g., Civitas or phosphites) to control snow mold in areas where snow cover persists.
  • The combination of three or more active ingredients applied at Marquette, Wis., resulted in 16 of 63 treatments with less than 5 percent disease, and at Wausau, Wis., 28 of the 63 treatments allowed less than 1 percent disease to occur.
  • Almost all effective mixtures included a DMI fungicide (tebuconazole or propiconazole), a contact fungicide (chlorothalonil or PCNB) and an additional active ingredient such as pyraclostrobin, azoxystrobin or iprodione.
This is posted in From the Magazine, Research

About the Author: Mike Kenna, Ph.D.

Mike Kenna, Ph.D., is the retired director of research, USGA Green Section. Contact him at mpkenna@gmail.com.

About the Author: Kevin Morris

Kevin Morris is the executive director of the National Turfgrass Evaluation Program. You can contact him at kmorris@ntep.com.

About the Author: Cole Thompson, Ph.D.

Cole Thompson, Ph.D., is a turfgrass scientist at California Polytechnic State University, San Luis Obispo, Calif.

About the Author: Paul Koch, Ph.D

Paul Koch, Ph.D., is an assistant professor of plant pathology at the University of Wisconsin-Madison where he conducts research and provides information to professional turf managers on disease management and control. Koch's research article in the August 2013 issue of Golfdom, "Beat the summer heat, plan for snow mold," won a TOCA Award (merit) for turf feature article. Koch can be reached at plkoch@wisc.edu.

About the Author: Marco Schiavon, Ph.D.

University of Florida

About the Author: Ana Luiza Sousa, Ph.D.

Sousa, Ph.D.is a postdoctoral researcher in Koppenhöfer’s program.

About the Author: Ryan Geisert, Ph.D.

Geisert, Ph.D., is a postdoctoral researcher in Koppenhöfer’s program.

About the Author: Bruce Clarke, Ph.D.

Bruce Clarke, Ph.D. is an extension specialist in turfgrass pathology at Rutgers University.

About the Author: James Murphy, Ph.D.

James Murphy, Ph.D. is an extension specialist in turfgrass management at Rutgers University.

About the Author: Ben McGraw, Ph.D.

Ben McGraw, Ph.D., is an associate professor of turfgrass entomology at The Pennsylvania State University. He can be reached at bam53@psu.edu.

About the Author: Wendell Hutchens

Wendell Hutchens earned his MS degree at North Carolina State University, and now is a Ph.D. candidate at Virginia Tech University. You may reach Wendell at wendelljh@vt.edu.

About the Author: Travis Gannon, Ph.D.

Travis Gannon, Ph.D., is at North Carolina State University

About the Author: Dave Shew, Ph.D.

Dave Shew, Ph.D., is at North Carolina State University

About the Author: Khalied Ahmed

Khalied Ahmed is at North Carolina State University

About the Author: Bruce Branham, Ph.D.

Bruce Branham, Ph.D., is a professor of turfgrass science at the University of Illinois and can be reached at bbranham@illinois.edu.

About the Author: Matt Sousek

Matt Sousek, research manager, University of Nebraska-Lincoln, can be reached at msousek2@unl.edu.

About the Author: Zac Reicher, Ph.D.

Reicher is a turfgrass scientist at the University of Nebraska-Lincoln where he works with professional turf managers, teaches and conducts research. Each year Reicher conducts annual grass weed-control experiments that he uses to help formulate weed-control recommendations. Reicher can be reached at zreicher2@unl.edu for more information.

About the Author: Aaron J. Patton, Ph.D.

Professor of Horticulture, Purdue University


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