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The Bizarro Weather

July 31, 2009

The state experienced below normal temperatures during the month of June and we just concluded a very mild July! The weather this year has been downright bizarre and reminds me of the Seinfeld episode where Elaine replaces her normal group of Jerry, George, and Kramer for her Bizarro friends Kevin, Gene, and Feldman who possess opposite, more attractive characteristics. A generous, agreeable mailman named Vargas even surfaces as a replacement to Jerry’s arch nemesis Newman. The weather during July seemed to follow this trend. We had September temperatures in July.

I was curious just how bizarre the weather was so I looked up the historical weather data in Ames for the month of July going back to the year 2000. The average high temperature for the month was 78.7 degrees. This ranks as the coolest average high temperature in the last decade. Similarly, the average low temperature was 59.3 degrees which also ranks as the lowest in the last decade. (In case you were wondering, the warmest July in the last decade was in 2002. That year the average high temperature was 86.3 degrees and the average low temperature was 65.6 degrees).


Of course, the benefit of the cool temperatures has been low disease pressure compared to what we normally experience this time of year. Just don't forget to grab a light jacket on your way out the door this morning.

Marcus Jones

Graduate Research Assistant


Disease Review: Brown Patch

August 13, 2009


It seems as if summer has finally caught up with us. An unusually mild July has left us and August has brought with it more typical Iowa summer weather. With increasing temperatures and humidity, coupled with the rain we received this past weekend, conditions have once again become favorable for disease development. Out at the ISU Horticulture Research Station we started our week off by discovering an outbreak of brown patch on some of our creeping bentgrass greens.




The turfgrass disease known as brown patch is caused by the fungal pathogen Rhizoctonia solani and can affect all of the cool-season turfgrass species. Brown patch is a summer disease whose development is triggered by hot, humid weather, night time temperatures above 65°F and long periods of dew. During these conditions brown patch may appear overnight. Brown patch is also considered a high nitrogen disease and excessive amounts of nitrogen in your fertility program during the summer can contribute to a brown patch problem.

Brown patch usually produces a circular brown to olive green patch with a grey perimeter giving a ‘smoke ring’ appearance. Often, more than one patch will be evident in an affected area with the appearance of the unique ‘smoke ring’ pattern more clearly defined on low mown turf. Individual leaf blades of the affected turfgrass will show lesions with a chocolaty brown margin. The brown patch lesions are most visible when observed on tall fescue, although they are present on all turfgrass species infected with brown patch.




One of the easiest ways to decrease disease pressure from brown patch is to implement a proper fertility program to avoid excess nitrogen during the summer months. Also, trying to promote shorter dew periods by avoiding late evening irrigation can help reduce the possibility of a brown patch. There are also a number of fungicides that provide brown patch control such as Heritage, Daconil, Medallion, Clearys 3336, and many others.

Nick Dunlap
GCSAA Campus Representative
Turfgrass Management
Iowa State University




The Heat is On

June 22, 2010

Summer officially began yesterday although it has felt like summer for some time now. The temperatures forecasted for this week should create ideal conditions for disease activity. Our research facility has a buffet of diseases right now. I have seen red thread, leaf spot, yellow tuft, fairy ring, dollar spot, and brown patch just in the past week. The high stress conditions could also spur on anthracnose. If you think you have anthracnose, look for the black colored fruiting bodies on the leaves of plant. The fruiting bodies, or acervuli, are best viewed using a hand lens or hand held macroscope. More information about identifying anthracnose and management of this disease can be found by clicking here.

A droughty month of May has given way to a wet and rainy June. Weather is the great equalizer in the turf business and this season has been a rollercoaster compared to the steady temperatures we experienced in 2009. Overall, our day and nighttime temperatures have been warmer this year compared to 2009 for the month of June. It was this same time last year that we experienced a warming trend that sent temperatures into the mid 90’s. But so far the biggest difference in weather has been the rainfall. Twenty days into June last year, Ames had received 1.95 inches of rain compared to the 6.36 inches of rain we have gotten this year.

Golf fans saw Irish golfer Graeme McDowell win the 110th U.S. Open on Sunday by shooting even par over four rounds at Pebble Beach. Coming into this tournament I had no idea who Graeme McDowell was but I quickly gained respect for him when listening to his post round interview. While reflecting on what he had just accomplished, and in amongst his numerous thank-yous, he took time to thank the maintenance staff for all their hard work and commented on the great condition of the course. Classy move Mr. McDowell, now off to Disney World you go!

Marcus Jones
Graduate Research Assistant



July 7, 2010

Nick Christians, Iowa State University

June has been extremely wet and there have been a number of temporary flooding events in Iowa this spring. A common question the last two weeks is “how long can grass stay under water and still survive?”

As with so many other things, there is no one good answer to this question. In my experience it varies with several different factors. They include the species of grass, the condition of the grass going in to the flooding event, time of year, the amount of silt build up, the depth of the water, the temperature, the soil type and probably several other things that are hard to observe.

Creeping bentgrass is surprisingly tolerant of flooding. This is followed by Kentucky bluegrass, and then perennial ryegrass and annual bluegrass. I have seen bent go under water for up to 5 or 6 days in the cooler temperatures of spring and still survive when the water goes down. I have also seen bent die in a few hours when it’s hot and the water is shallow, allowing the temperature of the water to heat to high levels. Bent also seems to do fine for a few days under deeper water in summer, particularly if the water keeps moving and the grass stays cool.

The green tissue of bluegrass seems to die easily, but the rhizome system stays alive and the area usually recovers from rhizome growth. When I worked in Colorado, I saw bluegrass fairways under water for several days followed by several days of silt cover. The silt was cleaned off and there was complete recovery a few weeks later from the rhizomes. Unfortunately, annual bluegrass comes back from seed and recovery usually takes a few weeks. Ryegrass has no rhizomes and unless there is a lot of seed in the soil, the area needs to be reseeded.

Another thing that I have noticed with bent is that if there are repeated, short flooding events , such as occurred in 1993, it recovers the first few times, but finally gives up and dies.


Several of you have experienced flooding over the years. What has your experience been? Send a short paragraph of what you have experienced to my e-mail address, and I’ll post them for others to read. Pictures would be useful if you have them. You can also use the comment section below to respond to this post.

The pictures below were from the week of June 28 on Ames Golf and CC. Supt. Mark Newton will be posting some information on what happened to these flooded areas in the next couple of days.



August 3, 2009

It's that time of year again when summer induced chlorosis begins to show up on lawns, golf courses, and sports fields. I have already had a few calls on this problem. Summer induced chlorosis is a yellowing of the turf that occurs as temperatures rise in midsummer. We normally see it in late July and into August. This year has been a little cooler than normal, but the few warm days that we have had are triggering the problem in some areas.

David DeVetter, a graduate student at ISU, completed a masters project on this in 2007. Here is the link to the article.

Nick Christians