Fungicides, Gray Leaf Spot, Turf Events and More

July 29, 2010


There is confusion on where turfgrass samples should be sent for diagnostic work. Please send all turfgrass samples to the following address, NOT to Reynoldsburg.
C. Wayne Ellett Plant and Pest Diagnostic Clinic
Department of Plant Pathology
201 Kottman Hall
2021 Coffey Road
Columbus, Ohio 43210
(614) 292-5006


Fungicide recommendations for 2010 for turfgrass are now available. This year's revisions on turfgrass fungicide recommendations can be found on the OSU Turf Disease website. Click here for the latest version of the bulletin "Management of Turfgrass Diseases." The latest “Families of Fungicides for Turfgrass” chart is also posted.


This KILLER disease of perennial ryegrass has been confirmed in Kentucky and Pennsylvania in the last three weeks. This is approximately one month before normal. So watch for this disease. Some key points.
- Kills perennial ryegrass;
- A common disease on ryegrass fairways and ryegrass athletic fields;
- Ky. Bluegrass, other bluegrasses, bentgrass, and fescues, … are NOT affected (a good diagnostic tool);
- Occurs in hot, humid, wet conditions;
- If there is a history check for this disease frequently;
- Send in samples to clinic for confirmation; and
- To protect turf with fungicides START NOW, do not delay!


- 2010 Turfgrass Research Field Day – Wednesday August 11 @ OTF Research and Educational Facility OSU Columbus, Ohio
- 16th Annual Ohio Lawn Care Summer Seminar – Thursday August 12 @ OTF Research and Educational Facility OSU Columbus, Ohio


We are seeing cases of well intended turf managers damaging turf with chemical applications.
- Avoid herbicides in periods of excessive heat;
- Avoid or limit the use of ALL chemicals on wilted or severely stressed turf;
- Limit the combination of products;
- Follow labels very carefully, or be more conservative in these stressful summer conditions;
- When in doubt … DO NOT spray and / or spread; and
- If you do not know what to do… DO NOTHING!
Time to throw in the Kitchen sink?
Well… Not quite yet. No one knows better than the tenders of the turf what a “challenging” summer you have had to grow and keep turf healthy. We have been hearing a lot of managers are “throwing the entire chemical closet” at their weak and dying turf. We think it’s time to rethink the “kitchen sink” philosophy. First go back and look at your chemical program. This summer’s weather pattern has shifted disease pressure and timing; make sure you have the right chemicals in the tank to cover the “disease of the week”. Take a look at the rates and application windows of your chemicals. If the label says 14 days, we would suggest that maybe 10 days is all the coverage you can expect in our current weather and disease pressure pattern and use at the highest label rate if this does not increase possible phytotoxicity. Watch what you are putting in the tank, the “more is always better” theology may not serve you well with the extreme high temps and humidity. In other words what may have worked as a 5 - 9 plus product tank combination may no long be safe in our current conditions. For some, this does still not help to answer that magical question of how to keep things alive this summer. Although not popular we recommend raising mowing heights to decrease pressure on the turf. Watch your water very closely; the weather and light winds we are seeing in the afternoon have the RT very high. What turf seems healthy and watered dries out much faster than we are used to. Concentrate on turf health, monitor your fertility; look at adding in a phosphorous program to reduce stress on the turf. All these may sound to the board or members as very unpopular ideas in our world of super stimping greens numbers, but our belief is that it is better to have grass and survive this summer than to not have grass and be figuring out how to seed or sod to get the course back in shape.


Prolonged periods of high temperatures and in some cases, excessive rainfall, and high humidity have made life uncomfortable for golfers and golf courses alike, with Mother Nature holding all the cards for true relief.

"The simple fact is the cool-season turfgrasses such as bentgrass, fescue, bluegrass, annual bluegrass (Poa annua) and others are stressed when temperatures climb and humidity is high," Clark Throssell, Ph.D., director of research for the Golf Course Superintendents Association of America, said. "Golf courses in many parts of the country experience this every year, however what makes the situation so dire this year are the high levels of extended heat and humidity, and the sizeable part of the country affected (Midwest, Mideast, Northeast and Mid-Atlantic)."

According to Throssell, golf facilities and those entrusted with managing the golf course – golf course superintendents – are not alone in this battle with the elements. However, the nature of their product makes their challenge greater.

"We are certainly seeing homeowners, athletic fields and businesses suffer turfgrass damage brought on by the conditions," Throssell said. "What makes it more difficult for golf facilities are the mowing heights are much lower and traffic is much heavier. That just adds to the stress on the turfgrass."

Throssell indicates that golf course superintendents are addressing the issue with a variety of management practices to make sure turfgrass survives. While there may be some short-term impact on playability of the course, the alternative is the loss of grass, the closure of the course and the additional costs of re-establishing playing surfaces (primarily putting greens).

He also cautioned golfers from thinking that water, whether from rain or irrigation, is the answer to the ills. There is a difference between heat stress and drought stress. Adequate irrigation will alleviate drought stress. Adequate irrigation will not alleviate heat stress. It is not only possible, but likely, for a turfgrass plant to be adequately watered and still suffer from heat stress under extended periods of high temperatures.

Among the practices that superintendents are implementing to manage golf courses include:

•Raising the mowing heights of playing areas, most notably putting greens;
•Alternating daily practices of mowing and rolling putting greens, with consideration to skipping a day if the schedule of play allows;
•Forgoing double mowing, topdressing, verticutting or grooming greens;
•Watering to provide adequate soil moisture, but not over watering as saturated soil will cause the turfgrass to decline rapidly;
•Hand watering as much as feasible. If a green has a dry spot or two, superintendents will hand water the dry spots only and will not water the entire green. When the entire green shows stress from a lack of water, superintendents use the overhead sprinklers and water the entire green;
•Avoid aerifying using large diameter tines that penetrate deeply into soil and remove a core of soil. If a superintendent feels the putting surface is sealed, venting using small diameter solid tines or other similar technique is employed;
•If fertilizer is required, small amounts of fertilizer are applied via a sprayer and observation of the response occurs before fertilizing again; and
•Monitoring and adjusting golf car traffic patterns to minimize stress to turf.

Throssell indicated that during periods such as this, it becomes easy to compare golf course conditions and pressure decision makers into actions that might prove detrimental to the long term health of the playing surface.

"Communication is vital," Throssell said. "Superintendents, golf professionals, owners, managers and others must be in constant contact with golfers to educate them on what is happening at the facility. But golfers must also understand that golf courses are like snowflakes – no two are alike. Some courses may be able to withstand the challenges of Mother Nature better than others because of better drainage and soil conditions, better air flow due to the placement of trees, less traffic or the presence of greater financial resources.
"We know the weather conditions will become more agreeable. What is important right now is to manage the golf course in a manner so that turf can be kept alive until that point."
GCSAA is a leading golf organization and has as its focus golf course management. Since 1926, GCSAA has been the top professional association for the men and women who manage golf courses in the United States and worldwide. From its headquarters in Lawrence, Kan., the association provides education, information and representation to more than 20,000 members in more than 72 countries. GCSAA's mission is to serve its members, advance their profession and enhance the enjoyment, growth and vitality of the game of golf. The association's philanthropic organization, The Environmental Institute for Golf, works to strengthen the compatibility of golf with the natural environment through research grants, support for education programs and outreach efforts. Visit GCSAA at