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Name That Patch – Early Spring Brown Spots

March 28, 2011

Parts of the Midwest are getting hit with another round of snow but there is no denying that spring continues to inch closer by the day. In fact, before this last blast of winter weather, spring activities were slowly getting underway. Trees were beginning to break dormancy, bulbs were peaking through the soil, and lawns were starting to green up.

This process has already started across parts of the Midwest and some of you may have noticed patches, or areas of brown in your lawn. It’s typical to receive a number of questions from your clients about the cause of these brown spots during spring green-up. There are a number of reasons why these patches can appear and this article will address some of the most common reasons and discuss what action, if any, is needed to remedy the situation.

Dormant warm-season grasses
Most lawns in the upper Midwest contain cool-season grasses like Kentucky bluegrass, perennial ryegrass, and tall and fine fescues. Occasionally lawns, or parts of the lawn, will contain warm-season grass species. Examples of these could include zoysiagrass, buffalograss, or nimblewill. Whereas cool-season grasses grow best in the spring and fall, warm-season grasses prefer the mid-summer months and will remain dormant (brown) longer into the spring until warmer temperatures arrive.

If zoysiagrass or buffalograss are the cause of your brown spot there isn’t much you can do other than exercise patience until warmer weather arrives. Nimblewill can be selectively controlled with Tenacity herbicide. Tenacity herbicide will be made available to homeowners later this spring. Consult a lawn care professional for more information about Tenacity herbicide.

Dormant patches of nimblewill are very noticeable early in the spring.  Nimblewill can be selectively controlled with Tenacity herbicide.  Consult with a lawn care professional about the availability and use of Tenacity herbicide.


Warm-season grasses such as buffalograss are still brown while cool-season grasses such a fine fescues begin to green-up.

Leftover annual grassy weeds
Annual weeds such as crabgrass are always a concern and last year they seemed to be particularly troublesome. In lawns that had severe outbreaks, some of these annual grassy weeds may still be present. The good news is that you don’t have to worry about controlling leftover annual weeds. They have completed their lifecycle and are no longer alive. They did however drop seed and you may consider using a pre-emergence herbicide for the upcoming season.


Goosegrass, an annual grassy weed, is still present from the previous growing season. 

Snow molds
Damage from pink and gray snow mold is most evident shortly after the snow melts. The grass will usually appear off-color and be matted down. Chemical applications to control snow molds in the spring are seldom recommended as most of the damage has already taken place. You can help your lawn by raking up the matted areas of grass with a leaf rake. Chances are there is some live turf hiding underneath. The picture below shows an area of gray snow mold on the Iowa State University central campus.


Gray snow mold on the Iowa State University campus. 

Dog spots
Damage from animal urine will definitely create brown spots in the lawn. Where you can usually count on some recovery from snow mold damage, dog spots are very effective at killing grass. The best course of action is to remove the dead grass, break up the soil with a hand trowel or rake and re-seed the area. Note: Seed will not germinate and grow if a pre-emergence herbicide is to be used. The exception to this rule is when Tenacity or Siduron herbicides are used. Consult with a lawn care professional for more information about these products.


Man's best friend.  Undoubtedly charming, but damaging to grasses.

Salt damage
De-icing materials that contain sodium can be quite harmful to turf. Brown patches or areas of turf along driveways, sidewalks, or streets could be caused from salt damage. Depending on the severity of damage, reseeding may be necessary. Aerification and watering (or rainfall) can help flush salts through the soil profile and improve the conditions of the site.

Marcus Jones
Graduate Research Assistant

Nick Dunlap
Undergraduate Research Assistant



June 19, 2013

Here is some additional information on the bermudagrass on the Dowling High School baseball field in West Des Moines, Iowa.  The pictures are from Eric Van Ginkel of the Iowa Cubs, who is involved in the care of the field.  It shows the problem of bermudagrass stolons encroaching on the infield.  This is not a problem with the Kentucky bluegrass or perennial ryegrass, because neither has a spreading rhizome.  If any of you involved in sports turf management have noticed this on your fields recently, it is likely either bermudagrass of Zoysiagrass.  While Zoysia is more common in Iowa turf, the bermudagrass is increasing in the region and has the most aggressive stolon growth of the two species.  We are also seeing more of it in Iowa lawns.  Watch for stolon growth over the sidewalks and drive ways.




March 28, 2013

Here is a common question at this time of year.  It comes from the answer line at ISU.

The question is, "I have a patch of grass in my lawn that turned brown early last fall and is not greening up this spring.  What is it?"

It is Zoysiagrass, a warm-season species that is becoming an increasing problem in Iowa lawns.  It is very hard to kill.  Roundup will set it back, but it always seems to survive, even after multiple applications.  I have seen people treat it with Roundup, then remove the sod and sod Kentucky bluegrass over the spot.  It still comes back.

Good luck if you have this one in your lawn and want to get rid of it.



November 1, 2012

Here is a post from Omaha concerning a reddish discoloration of Zoysiagrass.  I need some feedback from you Zoysia experts.


It is from:

Rob Elder
Owner, Omaha Organics Lawn Care


Rob has several Zoysia lawns, most of which look fine.  This one has taken on a reddish discoloration late in the season.

He uses a 4 step organic program on it.  He also put down gypsum in August for a sodium problem.  He topdressed it with organic matter.Sodium does not appear to be high on the soil test.

He gave me the soil tests and phosphorus in in an adequate range.

Some varieties of grass will turn red in the fall when temperatures cool, but this is the only Zoysia lawn that it is occurring one.  Does anyone with Zoysia experience out there have any ideas.  Let me know or contact Rob directly.

 Here is the reddish color on the Zoysia from a couple of weeks ago, just before dormancy.

Here is the lawn a couple of days ago, after the Zoysia became dormant.

 Heavy clay soil on the lawn.


Early Zoysia Green-Up in the Transition Zone

April 3, 2012

Here is a post from some friends in St. Louis. Ryan was an Iowa Stater who graduated 3 years ago. They are also having a very early spring.

By: Ryan Madden and Nick Zerr

Nick Zerr is the Class A Superintendent at Sunset Country Club in St. Louis, Missouri.

Ryan Madden is an Assistant Golf Course Superintendent at Sunset Country Club in St. Louis, Missouri.

With the unseasonably warm temperatures during the entire month of March, Zoysiagrass has not only begun to green up and emerge from dormancy, but it is growing in full force. At Sunset Country Club in St. Louis, Missouri we have Meyer Zoysia tees and fairways. As of March 21, 2012 we have had 755 growing degree days compared to 560 on the same date in 2011 using 32 degrees as a base. Usually we see green up sometime in mid to late April and do not begin to mow our Zoysia until late April to early May. However, this spring has already thrown us for a loop. We began to see our Zoysia emerging from dormancy the first full week of March. It was completely greened up and out of dormancy by March 21st and we began to mow it the last week of March. We have noticed that our fairways are a week or more ahead of our tees. We can contribute this difference to mowing height. The higher the mowing height in late summer and early fall, the faster the Zoysia emerges from dormancy the following spring. Obviously, the turf is healthier at a slightly higher mowing height and endures winter stress and dormant herbicide applications much better. Our biggest concern with early Zoysia green up is the threat of a freeze or a heavy frost. In St. Louis, we are not frost free until May 5th and in 2011 we had a frost as late as May 11th. Our preventable measures for frost include raising our mowing heights this time of year and running our irrigation system to burn off any frost after it occurs.




You can see our tees in the foreground are still mostly dormant while our fairway in the distance has emerged from dormancy. Picture taken March 21, 2012


Same picture as above but taken March 23, 2012.


This is a different location on the course as the previous pictures but a closer view. Picture taken March 21, 2012.




This picture is of the same fairway as above, but a very close view. Picture taken March 21, 2012.



Same picture as the ones above. However, this one is taken after our first mowing on March 26, 2012.





June 16, 2011

Imprelis (aminocyclopyrachlor) was released by DuPont Professional Products into the turf market this spring as a broadleaf control. It is part of a new chemical subclass called pyrimidine carboxylic acids. We have studied this product experimentally at Iowa State for the past couple of years and have found it to be very effective against a broad spectrum of broadleaf weeds. Its advantage is that it is effective against several hard to control weeds such as ground ivy, violets, and henbit. It also has the advantages of being applied at very low rates of active ingredient and is rainfast, meaning that it does not need to remain on the weed leaves for a period of time. It's safe on most cool-season grasses and some warm-season grasses, including zoysiagrass.

In early June, a number of reports on tree damage on areas treated with Imprelis began to come in. The first reports that I heard were from the east coast. Then pictures and reports started coming in from Chicago. Yesterday, I heard that there are several reports from the Atlanta area. The two most commonly damaged trees have been Norway spruce and white pine.

It is important to note that there are many locations where the product was used and no tree damage has occurred. Also, not all trees on the treated areas are damaged.

The pictures below are Norway Spruce and were taken in the Chicago area. The damage appears to be systemic, meaning that the material is being taken up by the roots and translocated to new growth. On this site, about 20 trees out of approximately 120 susceptible plants were damaged. In this case, there was heavy rain after treatment that may have increased movement of the product into the rootzone.

Dupont released a letter last night to users of the product. Their recommendation is as follows:

"As a precaution, until we can more fully understand the circumstances, and whether Imprelis may have contributed to the observed symptoms, do not apply Imprelis where Norway Spruce or White Pine are present on, or in close proximity to, the property to be treated.  Additionally, when applying Imprelis, be careful that no spray treatment, drift or runoff occurs that could make contact with trees, shrubs and other desirable plants, and stay well away from exposed roots and the rootzone of trees and shrubs.  Consult a certified arborist if you are uncertain about the root zone of specific tree species."

My personal recommendation is to be very cautious with the use of this product until we know exactly what is going on. This story is just developing and I will keep you posted as new information is released.

Here are some additional links.

Imprelis on Tree






November 22, 2010

This is a final summary on the recovery of the intramural field on campus that was damaged during the flood in August.

The first picture was taken a few days after the flood. The bluegrass/rye turf is dead. The grasses that survived are all warm-season grasses. Most of it is Bermudagrass, but there is also Zoysiagrass and Buffalograss on the site. This grass was established over the steam tunnel several years ago.

The second picture shows Kentucky bluegrass beginning to recover from rhizomes. It was taken a couple of weeks after the flood waters receded.

The third picture shows one of the turf lab groups on the site in September. They are standing on the warm-season grasses. The surrounding area was reseeded shortly after the flood and the blue/rye area has nearly recovered.

The final picture was taken in November of 2010. The blue/rye area has completely recovered and the warm-season grasses have gone dormant for the season. Little by little, the campus is returning to normal. The final bill for the flood damage was in the range of 50 million dollars.



August 24, 2010

These two pictures are both from the intramural field on ISU campus. The first one is from last November. It shows a strip of warm season grasses that have been planted on the steam tunnel that runs through the area. They include bermudagrass, zoysiagrass, and buffalograss. They are all dormant as would be expected in November. The Kentucky bluegrass/perennial ryegrass turf is green.

Now look at this picture taken yesterday, Aug. 23, 2010, approximately two weeks after the flood. This area was completely under water for at least 3 days. The bluegrass/rye is dead (although I think the rhizomes of the bluegrass are alive) and the warm-season grasses have recovered. This is a good demonstration of how well warm-season species can take flooding.



August 14, 2010

Greetings from Hong Kong. I am having a great time and learning a lot.

Here is a picture of Damian Richardson, intern at Hong Kong Golf Club, pointing to the tropical carpetgrass rough. This is a very unusual species. The only other place that I have seen used in golf is Jamaica. It makes a great rough here, because it is not very invasive into the other turf areas. The fairways are an interesting combination of bermuda and zoysia.

Here is a close up of the tropical carpetgrass. The leaves remind me of miniature corn leaves. It has a dense stoloniferous growth habit and lays flat along the ground surface.

The local Chinese don't like exposure to the sun. Notice the hats that the cadies wear and the long sleeves.

Here is one of those local problems. Giant snails that tend to get on greens and cause problems for greens mowers.