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Singing the Low Mow Blues

July 26, 2010

This post comes from John Newton, CGCS, Veenker Memorial Golf Course. Veenker renovated their facility during the fall of 2008. Part of the renovation involved converting the intermediate cut of rough from common cultivars of perennial ryegrass to low mow Kentucky bluegrass. John’s note is below:

After a great opening spring with some of the new varieties of low mow bluegrass, I very impressed with the color, density, winter survival, and establishment after only 18 months of establishment. It sure looked like the perfect turf for central Iowa.

Currently, it is having a real difficult time and is very thin in some areas, especially in areas of partial shade. The damage seems to be from various disease infestations and generally appears as a weak, poor looking turf. I have to say I’m very disappointing after the success with removing the annual bluegrass out of the bluegrass last fall and this spring with Tenacity herbicide.

 

 

 

 

 

 


 

 

 

 

 

 

 

I’m not sure about a plan of action moving forward because some of the older turf varieties right beside the low mow blues look great, along with the ryegrass, the bentgrass fairways, and some of low mow bluegrass that was treated with Heritage in mid June. The Heritage application was made to the fairways but in spots where the booms hung over into the intermediate cut the bluegrass looks great. That was our only fungicide application to our bentgrass until recently. Probably a combination of leaf spot and patch disease’s just disappointing that we now will need to treat these new varieties. One of the main reasons for the conversion was to cut our applications of fungicides and other chemicals. The bentgrass fairways so far have been great.

One thought that crossed my mind was that it may be only certain cultivars that are susceptible to the damage. The low mow blues we used were a 4 way low mow blue mix. I would be interested to hear what others who have also converted to this turf are experiencing.

John Newton, CGCS
Veenker Memorial Golf Course

Category: 

More Ascochyta Disease Across the State

August 17, 2011

Dave Minner, ISU Extension Turfgrass Specialist
Mark Gleason, ISU Extension Plant Pathologist
Erika Saalau, ISU Plant Diagnostic Clinic

For the second year in a row Ascochyta has hit lawns, athletic fields, and golf course turf. Ascochyta leaf blight is a grass fungus that causes a rapid straw to bleached appearance of the leaves primarily on Kentucky bluegrass and to a lesser extent on perennial ryegrass and tall fescue. The damaged lawns started showing up around the first of June and out breaks have been occurring all summer long. Some of the more severely damaged areas may require 3 or 4 weeks of good growing conditions to fully recover.

The damaged areas seem to occur very quickly; one day the grass appears fine and the next there is bleached tan grass everywhere and most noticeably where the mower tires track. In fact, to those unfamiliar with this problem they think that someone has damaged the lawn with a pesticide or fertilizer application. The Ascochyta related problems I am seeing have nothing to do with product applications. The fungus likes to grow during wet conditions favored by lots of rain or over irrigation. Infectious spores are everywhere throughout the lawn and with a sudden increase in hot temperatures they rapidly infect the stressed grass.

Tire tracks show up because the tires spread the spores and also cause just enough abrasion stress for the fungus to enter the plan tissue. Look for bleached leaf tips that are collapsed. It looks devastating because the top part of the plant is severely damaged but the crowns and lower stems are seldom killed. The attacks are so haphazard that it is impossible to give a good recommendation as to when to avoid mowing but in general raising the mowing height and mowing less frequently will reduce your chance of experiencing a mowing track incidence. It is interesting to note that Ascochyta blight in home lawns only occurs in full sun areas and it stops where the shaded lawn has less heat stress.

The damage at first appears very dramatic but the good news is to simply be patient because most of the damage is on the leaves while the crowns and roots of the plant are not damaged. As the plants continue to grow and after about a month of normal mowing the damaged leaf tips will be removed and the lawn will return to normal.
Normally we don’t recommend a preventative fungicide because it occurs too haphazardly and a curative fungicide doesn’t help after the leaf tissue is blighted. However, if you have experienced this in the same lawns and athletic fields for two years in a row you may want to consider a single preventative application of a fungicide next year from mid May to mid June.

Much of the turf I have sampled this summer has been confirmed to be Ascochyta by laboratory identification of spores. Like most of you old timers over the years I have observed tire tracking that we have assumed to be related to hot or dry conditions. Laboratory identification of the pathogen is the best way to determine if it was related to Ascochyta. Next year we will be conducting research with fungicides, moisture conditions, and wheel pressure to determine what is causing the tire tracking; is it Ascochyta or is it simply high temperature or low moisture stress. I think most of the blighting and wheel tracking we observed in June and July were associated with Ascochyta. To a lesser degree we may have also observed some wheel tracking from high temperature/drought stress.

Areas that have been severely injured can be recovered by dethatching, hollow tine aerification, and reseeding in September.

Here are some of the Ascochyta injured lawns that we have observed in Iowa during the summer of 2011.
 

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Ascochyta in mower streaks on athletic field in Iowa City, IA.  Picture taken 7/15/11.

 

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Close up of Ascochyta symptoms on Kentucky bluegrass.  Note the bleached leaf tips and banding of leaf blades.  These symptoms are different from dollar spot that has leaf lesions with bleached centers and brown boarders.

 

 

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Obvious tire tracks from mower associated with Ascochyta in Ankeny, IA.  Picture taken 5/20/11.

 

 

 

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Picture in Ames, IA showing wheel and deck tracks associated with Ascochyta.  Picture taken 6/16/11.

 

 

 

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Ascochyta can also injure lawns without leaving the mowing tracks.  Picture taken in Ames, IA 6/16/11.

 

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Wheel track lawn injury from Ascochyta but notice that the tracks are not present in the shaded areas where the grass has less heat stress.  The Ascochyta spores may be present everywhere but it usually requires a period of sudden heat or drought before symptoms appear.  Picture taken 6/1711 Ames, IA.

 

 

 

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More Ascochyta mower tracks from Parkersburg, IA.

 

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Darker green lawn (bottom) with higher nitrogen fertility shows more Ascochyta injury than lower fertility lawn (top).  Nitrogen applied at 2 to 4 lbs N/1000sqft/yr is suggested to maintain healthy lawn growth.

 

 

 

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Low maintenance (no fertilizer and no irrigation) Kentucky bluegrass along roadside showing mower tracks with Ascochyta injury.  Even though high nitrogen can cause lush growth that increases infection in this case turf was injured in a low nitrogen situation.

 

 

 

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Mowing tracks on golf course fairway.  Injury occurred during a period when turf was not wilted or under low moisture stress.  Grass died in lower wet areas but recovered on sloped areas.  Also notice that the tracks stop at higher cut rough in front of sand trap.  We will be conducting research next summer to discern what is Ascochyta related and what may be related to high temperature or drought stress wheel tracking.  Picture taken 7-20-11 Waverly, IA.

 

 

Category: 

UNUSUAL RYEGRASS??

November 16, 2012

We have been noticing some unusual areal shoots on what looks to be perennial ryegrass and we would like to hear from you if you have noticed anything like this at your facility. The pictures are from a football field in central Iowa.  The field is a mixture of Kentucky bluegrass and perennial ryegrass that has been infiltrated with some patches of K-31 type tall fescue.  Over the last three years it has been seeded with a mixture of Kentucky bluegrass and perennial ryegrass.  The ryegrass component was made up of GLS (Grey Leaf Spot) type ryegrass and Tetraploid Turf-Type ryegrass.  Our intent is to simply determine if others have observed this type of growth and if you consider it to be a positive or negative type of turf performance.

Please contact either myself or Andrew Hoiberg if you have seen anything like this:

Dave Minner (dminner@iastate.edu) (515-231-1741)

Andrew Hoiberg (android@iastate.edu)

 

 

 

 

 

 

 

 

 

 

 

 

 Thanks for your help.

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The importance of high-quality seed

October 10, 2013

Turfgrass establishment from seed can be a challenging endeavor. One key to successful establishment is the use of high-quality seed that is best adapted to each individual site. In the turfgrass industry, there are mixtures and blends of seed. A mixture is a combination of multiple species, while a blend is a combination of cultivars within the same species. For example, Kentucky bluegrass and perennial ryegrass in the same bag of seed would be a mixture of seed. However, a blend is a combination of cultivars of the same species such as Midnight and America Kentucky bluegrass. 

 

Seed Labeling Information


In most cases, the seed label is the best source of information pertaining to seed quality. By law, each seed package sold in the US must be labeled truthfully. However, labeling does have its downfalls and all consumers must be aware of the potential loopholes. There are no bargains when it comes to turfgrass seed. For a higher quality seed, you will have to spend a few more dollars. The availability of high-quality seed is limited and ultimately expensive to produce, which has led to the production of poor-quality seed.

The germination percentage should also be considered when purchasing seed. Seed should never have labeled germination rate below 85%. In addition to the labeled germination rate, time also play a huge factor in germination percentage. Seed germination decreases over time and germination rates may have decreased significantly since the original testing date. 

The percentage of inert matter tells you the weight of all nonseed material in the bag. Weed seed percentage is very important and is the total weight of all the weeds. In most cases, noxious weeds are of little concern in turfgrass because of the continuous mowing and defoliation following germination. Quackgrass is one of the few exceptions. 

The biggest loophole and seed contamination occurs in the percentage by weight of other crop seeds. Most of the worst weeds in turf are perennial grasses. Most of these perennial grasses are produced commercially, which group them into the other crop seed category rather than noxious weeds. Grasses such as bromegrass and tall fescue are particular problems. The species list of “other crops” is not usually listed on the label and it is hard to identify their potential impact in turfgrass seeding. To prevent issues you should always use high-quality seed from a reputable dealer. There are no bargains in seed and it is advisable to pay more now because it will save you money and headaches in the long-run. 

One example of this can be seen below with a yard contaminated with common perennial ryegrass. Common perennial ryegrass is usually found in cheaper seed mixes. It is produced at a lower cost than many of your elite perennial ryegrass cultivars. The common perennial ryegrass can be unsightly and drastically reduce turf quality. It has many of the same identification characteristics that you would consider a more desirable perennial ryegrass to have. Folded vernation (once closely observed from a microscope), short to midsized auricles possible, bunch type growth, potential red stem base (is absent in pictures below), divided collar, and a pointed leaf blade that rolls out of the sheath. Common perennial ryegrass however lacks the allure features of the more elite perennial ryegrass cultivars. It often grows awry and is perceived as a nuisance and weed species as seen in the pictures below. 

Category: 

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

Category: 

RUST DISEASE ON PERENNIAL RYEGRASS

July 22, 2014

On July 17, I received an e-mail from Larry Ginger of American Lawn Care with a picture of rust disease showing up on perennial ryegrass, but not on Kentucky bluegrass.  Rust is a fungal disease caused by fungi in the genus Puccinea.

Picture from Larry Ginger showing rust on ryegrass patch in lawn taken July 17.

I had not seen this problem at that time, but yesterday (July 21) I took data on the National Turfgrass Evaluation Program (NTEP) trial at the research station.  I found that many of the cultivars were covered with rust.  I took data on the rust problem this morning (July 22).  I have not seen the problem on the Kentucky bluegrasses as of today, but it clearly a severe outbreak on some of the perennial ryegrasses. Rust often shows up in August on Kentucky bluegrass, perennial ryegrass, and even on tall fesuce (see earlier blogs).  This year it is early and appears to be hitting the ryegrasses first.
 
 Close up of rust on Kentucky bluegrass from last year.

Rust spores on my shoes after taking data.

 Three pictures of individual ryegrass plots covered with rust on July 22.

 Rust is clearly cultivar specific and there were cultivars covered with it and adjacent plots that were completely free of the disease.  This is another reason for choosing your grass seed carefully.  There is usually a good reason to spend a little more on grass seed.  I have not analyzed the data on which cultivars were affected, but that will be in next year's report.  NTEP does have data available on ryegrass susceptibility to this disease at ntep.org.

Rust is a fungi and there are fungicides that control it, but we generally recommend that you let the disease run its course.  It usually goes away by itself.  You may want to treat on sensitive areas, such as sports fields if it becomes necessary.  

These plots will be on the tour at the turfgrass field day this Thursday, July 24.

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ISU GOLF TEE COMPLEX UPDATE-SPRING 2013

April 15, 2013

On January 11, 2013, Dan Strey reported on the new tee complex at the Iowa State Research area.  The new site had been seeded in the fall and covers had been placed on it for winter protection.  We lost a surprising amount of grass under the covers on the upper part of the tee this spring, even though the area had been covered.  Here is Dan's report on the spring results.  I do not have a good explanation for why we lost the grass on the upper part of the tee, I generally do not see this on covered areas.

 From Dan:
 
At the end of last year, I wrote about the construction of a new tee complex at the Horticultue Research Station. Well, the covers were finally removed this past week, and it was rather surprising what we found underneath.

The 80/20 mix of Kentucky bluegrass and Perennial ryegrass that was planted on the surrounds handled the winter well, especially in the areas covered. However, the bentrgrass areas had much different results. 

 

Horticulture Research Station

The bottom tee grew in well before the winter and was even mowed once before covering the area. We did observe yellow patch in late October, but the damage was rather minute. The bottom tee showed very little winter damage after removing the covers.

The top tee is another story. The area hadn’t germinated as well as the bottom tee last fall, but was still in pretty good shape.  As we removed the covers, I noticed the sand was extremely dry and there wasn’t green grass to be found. 

Horticulture Research Station

I am thinking that the area became too dry since the snow melted off.  The tee is located in an area that is exposed to winds from any direction. The probability of the turf recovering is rather small. We will most likely have to reseed the area this spring.

 

Category: 

GRAY LEAF SPOT IN CENTRAL IOWA

October 2, 2012

On September 4, I put up a post warning that Gray Leaf Spot might show up in Iowa because of the unusually warm conditions around labor day.

On the 4th I wrote the following:
"This disease is caused by the fungi Pyricularia grisea. It seems to selectively hit perennial ryegrass on intensely managed areas such as golf course fairways and sports fields. Under the right conditions, it can be more devastating than Pythium blight. When it hits, it can wipe out large areas of turf overnight.  Fungicides, such as Banner/Daconil will control it, but they must be applied before the outbreak.  Once the disease begins, it is too late to apply.  The reason I bring this up is that we are in the same weather pattern again this year.  The disease does not always occur when its hot around Labor Day, but it did last year and I would watch for it this year".

What I didn't know at the time was that it would be me that would get hit with the gray leaf spot.  When I went out to take data on the perennial ryegrass trial at the research station in mid September I found that the ryegrasses in the trial appeared to have collapsed.  They looked terrible.  I then looked at two other areas of perennial ryegrass on the site and saw that it looked the same.  Andrew Hoiberg, who recently graduated with his Ph.D. was at the station at the time and commented that it looked like gray leaf spot.  On closer inspection, that is what it appears to be.  It was right on time, shortly after Labor Day during an unusually warm spell.

This trial is part of the national turfgrass evaluation trials (NTEP) and we purposefully do not treat it with fungicides.  The damaged cultivars are beginning to show some recovery as of the beginning of October, but they are still showing signs of the damage.  Under normal conditions, we would simply reseed into the ryegrass and we would have it back in a couple of weeks.  We are unable to do that here because of all the different varieties that are involved.  We will have to wait for recovery.

By the way, is it Gray Leaf Spot or Grey Leaf spot?  You will see many examples of each if you search the internet.  I'm using Houston Couch's book as my source and going with Gray.

The pictures below are of the site in mid September when the damage was most severe.  The first three are of the NTEP perennial ryegrass trial.  The last four are closeups of the damage.

 

 

Category: 

ANOTHER GRAY LEAF SPOT WARNING

September 4, 2012

A year ago, on August 31, 2011, I put up a post warning about Gray Leaf Spot on perennial ryegrass.  This disease shows up rather infrequently in Iowa, but it does occur around Labor Day on years when temperatures are unusually high.  Last year's Labor Day temperatures were in the 90's and if you check the post from September 19, 2011, you will see that it did occur on several golf courses with perennial ryegrass fairways.

This disease is caused by the fungi Pyricularia grisea. It seems to selectively hit perennial ryegrass on intensely managed areas such as golf course fairways and sports fields. Under the right conditions, it can be more devastating than Pythium blight. When it hits, it can wipe out large areas of turf overnight.  Fungicides, such as Banner/Daconil will control it, but they must be applied before the outbreak.  Once the disease begins, it is too late to apply.

The reason I bring this up is that we are in the same weather pattern again this year.  The disease does not always occur when its hot around Labor Day, but it did last year and I would watch for it this year.

The pictures below were taken in 1998 on Willow Creek Golf Course in Des Moines and last year on Cedar Poine golf course in Boone. The dead grass is perennial rye and living grass is Kentucky bluegrass.

If anyone has an outbreak of Gray Leaf Sport this year, let me know and send some pictures. 

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