July 29, 2010

University of Arkansas, Division of Agriculture, Cooperative Extension Service

Turfgrass Science Program (http://turf.uark.edu) – Turf Tips

Will the golf industry ever catch a break in 2010?

It seems like only yesterday that we were sending out Turf Tips to our local industry about the potential for winterkill on warm-season turfgrasses and what to do about it. The truth is we had one of the more severe winters of the last 10 years and many golf courses, athletic fields, and other turf sites around the state and region had to deal with winter injury on their warm-season turfgrasses. In our research plots at Fayetteville, we saw significant winter injury on St. Augustinegrass, Seashore paspalum, bermudagrass, and even zoysiagrass (a first for me). 

I am not sure why I thought this, but the law of averages would suggest that a really bad winter should be followed by a nice, mild summer that lets everyone get caught up and recover from the problems of winter. Right? Unfortunately, we have followed a bad winter with one of the most difficult stretches of hot, humid weather that Arkansas and much of the United States has seen in the past decade or longer.

With the proliferation of social networking, blogs, and news media, it is easier than ever before to keep up with what is going on in the turf industry or any other aspect of society. One of my favorite blog sites out there is the turf disease blog site (http://turfdiseases.blogspot.com/), where some of the nation’s best turfgrass pathologists update their readers on the kinds of problems they are seeing in their region, especially as samples pour into their plant disease diagnostic labs. As I was visiting the site the other day, I was struck by the titles of the five most recent blogs posted on the site by these prominent turf researchers:

·         Poa annua takes a dump – Jim Kerns, Wisconsin

·         Heat + Rain = Dead Grass – Brandon Horvath, Tennessee

·         No wind = Dead grass – Lane Tredway, NC State

·         Heat wreaking havoc on golf courses nationwide – John Kaminski, Penn State, and Clark Throssell, Director of Research, Golf Course Superintendents Association of America

·         Relentless heat and humidity – Megan Kennelly, Kansas State

You really don’t even have to read the articles to know that things are tough all over. However, if you want a sense of what is going on around the nation, I suggest you read all these articles, especially the one by Kaminski and Throssell. In one of the articles, there was a discussion on this year’s weather compared to the past, so I started digging around in some of the weather archives to see where we are in Fayetteville, Arkansas relative to year’s past. Probably the most telling data is the number of days where we have experienced extreme temperatures. If you look at the 30-year average, July will normally have 13 days where the mercury rises above 90 °F. July 2010 in Fayetteville had 20 days where the temperatures went above 90. Normally, this would not be a huge problem, but this above-average July is following a June where we had 13 days above 90 compared to an average of 5 days over the last 30 years. The really bad news is that August is typically the hottest month of the year, so we are nowhere near out of the woods.

In addition to the excessive temperatures that we have been experiencing, we are also in a cycle of very high humidity, thunderstorms that add to the humidity and heat load, and minimal wind. All these factors create an environment that is almost impossible to keep bentgrass and other cool-season grasses going strong. If we go back to plant physiology 101, it is pretty clear how these extreme high temperatures might affect creeping bentgrass greens. Bentgrass has an optimum temperature for photosynthesis between 55 and 75 °F. When we exceed the 90° threshold, the ability of bentgrass to produce energy from photosynthesis drops dramatically. In addition, high temperatures cause respiration rates to increase, which means the plant is burning more fuel than normal. So, in total, we have a system that has reduced energy intake and increased energy consumption and that can only be sustained for short periods of time, not the duration we are currently seeing. A good analogy would be trying to reduce your food intake by 80% while running a marathon – within a short period, your energy reserves are going to be depleted and you will stop running.

The high humidity and limited wind is also an ideal environment for diseases to thrive and pathogens are attacking weakened plants at an alarming rate. One of our key research projects at the UofA is to screen grasses for adaptation to our environment and getting a lot of disease pressure is really good for our research. However, in my 13 summers at the UofA, I have never seen disease as severe as what we are seeing right now. I have over an acre of various tall fescue cultivars that has been almost completely wiped out by Rhizoctonia brown patch (see picture below). It is so bad that many Kentucky bluegrasses are getting brown patch, which is a rarity and I have never seen at Arkansas.



I have already had to visit a number of golf courses this summer that are struggling to keep greens alive and I really don’t have an easy answer on how to do it. Once the turf starts on a downhill spiral, it will not be able to fully recover until environmental conditions improve. Preventative fungicides, good fertility, proper mowing, fans, good irrigation practices, etc., are all critical as you move forward, but these are only band-aids that will keep the wound from gushing blood until cooler temperatures return. It is also critical for golf course owners and managers to understand that really bad weather, like cancer, does not discriminate based on wealth or social status, so golf courses with both unlimited budgets and shoe-string budgets will feel the consequences of the weather we are experiencing. Management and players need to have realistic expectations during stressful periods like this and not get too excited about a few weak spots on the greens.

In Kaminski and Throssell’s article on the turf disease blog, they listed the following recommendations for dealing with these conditions and they are good recommendations for Arkansas as well:

·         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.

·         Monitoring and adjusting golf car traffic patterns to minimize stress to turf.

The one strategy they failed to mention was prayer for a change in these weather patterns – football season cannot get here soon enough!! Hang in there and let us know how we can help.

Mike Richardson, Professor

University of Arkansas


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