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An Instant Classic, Kentucky Bluegrass decline, and a Big Storm

July 19, 2010

The Open Championship concluded over the weekend with first time major champion Louis Oosthuizen running away from the field for the victory. With three of the four majors completed the summer is off and rolling.

The Field Day Classic was held last week at Jewell Golf and Country Club. It was a great day despite the heat with temperatures reaching into the high 90’s and a heat index well over 100. The course was in great shape and the weather didn’t seem to hinder low scoring. Special thanks to Brian Abels and his entire staff for hosting and putting on a great event.


 

 

 

 

 

 

The hot temperatures have also been causing havoc to our cool-season turfgrasses as well. Soil temperatures are now reaching into the low 80’s causing root growth to stop. Research has shown that creeping bentgrass generally loses about three quarters of its root biomass from the end of May to the beginning of June. This natural root decline coupled with the extreme rainfall amounts during the month of June which caused roots to pull back has resulted in turf that is especially sensitive to environmental and fungal stresses.

I have seen Kentucky bluegrass beginning to decline over the last couple of weeks. The pictures below show a low-mow Kentucky bluegrass intermediate rough. After inspecting the area, the decline seemed to be the result of leaf spot/melting out disease. The disease activity was also more prevalent where the turf was under shade part of the day. Notice how the common type Kentucky bluegrass in the primary rough remains largely unaffected. Mowing height also appears to be playing a large role in the disease activity. Leaf spot can be controlled on a curative basis but applications are most effective in the early stages of the disease.

 

 

 

 

 

 

 

 

Diseases will continue to wreak havoc on our cool-season grasses the rest of the summer. For those of you with large acres of perennial ryegrass, the prime window for gray leaf spot is right around the corner.

On a side note, Ames and central Iowa had severe storms roll through Saturday night with winds reaching speeds of over 70 mph. While I kind of like severe weather I do not enjoy the cleanup. Waking up Sunday morning it looked like a bomb had went off in the neighborhood with plant debris and trees down everywhere. Luckily the picture below wasn’t from my house but wasn’t too far away. Hopefully the rest of you in central Iowa were able to avoid damage as well.


 

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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

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Dare I say it. Can we get a little rain?

October 18, 2010

We are just past the halfway point in October and some parts of the state have yet to receive any considerable rainfall this month. After being bombarded with rain during the summer months, the Des Moines area has received a measly 0.03 inches of rainfall so far in October. Their last considerable rainfall event took place on September 25. Depending on what happens the remaining 14 days of the month, October could go down as one of the driest on record. Irrigation systems that didn’t get much use during the rainy summer months are surely being used during this stretch of dry weather. The picture below from the National Weather Service shows that a good chunk of the Midwest is experiencing below average rainfall for October.
 

There hasn’t been too much activity (as far as stresses go) at the research station. We still have dollar spot working in some areas and rust and powdery mildew are showing up on Kentucky bluegrass. Grub damage at the station seems to be less this year compared to years past.

Other than the droughty conditions, the fall months have been conducive for turfgrass growth and recovery. Soil temperatures are holding steady in the high 50’s low 60’s. Those putting down natural organic fertilizers yet this fall, remember that those products require microbial activity to release the nitrogen contained in the product. Microbial activity usually ceases at 50 degrees. The dry conditions could also affect post-emergent herbicide applications as uptake and translocation are not as effective on drought stressed weeds.

I’ll leave you with some pictures of fall.

Regardless of the weather conditions, poa always seems to find a way to thrive.

This maple provides brilliant fall color on the north side of the ISU campus

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Help NTEP with a new Kentucky Bluegrass Trial

December 6, 2010

The National Turfgrass Evaluation Program (NTEP) is a non-profit organization that conducts research on the major turfgrass species. NTEP cooperates with state Universities across the U.S. to establish and maintain these trials. A number of testing sites are utilized in order to provide turfgrass managers with data specific to their region or state. We have a couple of NTEP trials at the Iowa State Turfgrass Research Station and if you have ever attended a Turfgrass Field Day you are sure to have seen NTEP research during your visit.

Many of you have probably heard of NTEP before and possibly even used their data. The NTEP trials record information such as turfgrass quality, color, density, resistance to diseases and insects, tolerance to heat, cold, drought, and traffic. I remember John Newton and myself using NTEP data to select cultivars of creeping bentgrass during the renovation process at Veenker Memorial Golf Course. We were interested in choosing cultivars that had dark green color and had good resistance to dollar spot.

Currently, NTEP is planning to initiate a new Kentucky bluegrass trial during the fall of 2011. They are seeking input from industry professionals on the direction of the study. Specifically, they are looking for input on the types of evaluations they should conduct, and the traits that you desire in Kentucky bluegrass cultivars.

You can provide your opinions for this new trial by conducting a short survey (only 8 questions) on the NTEP website. A direct link to the survey can be accessed by clicking here.

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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.

 

 

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Drought Damaged Lawns Need Help

September 25, 2012

While the drought of 2012 may be remembered more for its economic loss to corn and soybean farmers it also took a toll on many lawns across Iowa.  The crispy brown lawns of August have begun to recover with September rains, but all is not well.  Kentucky bluegrass is the most dominant grass in Iowa lawns.  In most summers when water is lacking the turfgrass leaves turn brown but the below ground crowns, buds, and rhizomes survive in a dormant condition only to produce new growth when water returns.  

 We have become very accustomed to letting the lawn turn brown in the summer and then watching it re-green in the fall.  The problem with this strategy is that summer dormancy is not an absolute guarantee that the grass plants will survive.   Most of the time non-irrigated lawns turn dormant in late July after about 2 to 3 weeks with no water.  They can remain brown and dormant, but alive, for approximately 4 to 6 weeks without water.  Again, these are general statements and estimates, not absolute values.  It is important to remember that the dormancy factor in Kentucky bluegrass also has its limit, and it was reached in many lawns across Iowa in 2012.  I have been driving through many new and older neighborhoods in Iowa to get a feel for the amount of turf damage caused by the drought.   

Older neighborhoods where trees shade the ground don’t seem to have as much turf loss.  Lawns with hills and slopes, especially those facing the south lost substantial turf.  Thatchy and sandy soil lawns left un-irrigated also experienced severe turf loss.  The green grass of watered lawns is easily discernible from the dormant lawns that are now struggling to recover.  My travels across Iowa indicate that most neighborhoods have approximately 25 to 50 percent of the lawns showing some degree of turf loss from the drought and of the injured lawns approximately 25 to 50 percent of the turf in each lawn has been killed.  The bad news is that some of you are now dealing with dead grass and no amount of watering or rain will make it recover.  In fact, the dead areas of the lawn that are not repaired this fall will likely be invaded by weeds next year.   

The good news is that September is the perfect month to renovate the lawn or at least reseed the damaged areas.   Don’t delay, if it is dead now it probably won’t recover and by the end of September and you will have missed the best seeding window to re-establish the lawn.  By the middle of August I determined that over 50% of my full sun Kentucky bluegrass backyard was dead.  So I set the mower as low as it would go and scalped off all the dead grass and what little green grass remained.  Next, two passes in opposite directions were made with a slicer seeder from the local rental store to plant seed in perfect little rows approximately one inch apart.  The shredding action of a verticutter or the hole punching action of an aerifier are other machines that could be used to facilitate inter seeding into the existing dead lawn.  Just make sure that you are getting the seed planted into the top ¼ to ½ inch of the soil.   Then lightly rake the surface to further plant any exposed seed into the surface.  Seed left on the surface usually remains too dry and seldom establishes.  Add fertilizer and water and watch it grow.  Water just enough to keep the top inch moist during the first two weeks; start by watering an area for ten minutes once or twice a day and adjust as needed.  There is no need to soak the soil deep because the seed is near the surface.    After the seedlings produce 2 or 3 leaves and are over an inch tall, reduce the frequency of watering to every other day and eventually to once a week. 

I seeded turf-type tall fescue on August 15th  and 28 days later my first mowing occurred on 12 September at 2.5 inches high.  I changed my front yard from Kentucky bluegrass to the more drought tolerant turf-type tall fescue three years ago and liked it so much that I was planning on killing my backyard with glyphosate and inter seeding tall fescue this year.  The 2012 drought did such a nice job of killing the old lawn that I didn’t even bother using herbicide.   If your lawn has a variety of weeds and other undesirable grasses use glyphosate to kill the undesirables and then seed into the dying vegetation.  Tall fescue is a bunch grass that could require some overseeding if it were to thin, however it has fewer disease and insect problems and because of a deeper root system will remain green about two weeks longer than Kentucky bluegrass when water is limiting and this ultimately means less irrigation is needed compared to a Kentucky bluegrass lawn.  

If you are not a fan of turf-type tall fescue then just reseed with Kentucky bluegrass or a mixture of 80% Kentucky bluegrass and 20% perennial ryegrass by weight.  Seed tall fescue at 10 lbs/1000 sqft and Kentucky bluegrass or the bluegrass/ryegrass mixture at 3 lbs/1000 sqft; both seed scenarios will cost approximately $12/1000 sqft or approximately $100 for an average lawn of 8000 sqft.  My cost for seed, fertilizer, and equipment rental to do 8,000 sqft of my lawn was $196 and my labor was free but I didn’t move real fast the next day.  A local lawn care company quoted me $280 for the same work and next time I just might watch them do it from my lawn chair on the porch.  Both could have been avoided with one ($86) or two ($172) timely irrigations to apply 1 inch of water per month during the drought to insure that my dormant turf did not die.  The take home message for 2012 lawns is that summer turf dormancy is no guarantee that the lawn will survive and that a little water is a good summer investment to avoid the expense and aggravation of having to re-establish a dead lawn. 

 

Prepare for a drought

Management practices in the fall and spring determine the drought tolerance of the lawn in summer. To reduce the need for irrigation, your lawn management program should maximize root volume and depth in preparation for summer drought. By the time summer rolls around, there is little you can do to help a lawn except mow and irrigate properly. The following lawn care tips will help reduce the need for irrigation and increase the chance of surviving summer drought.

  • Mow grass as tall and as frequently as possible with a properly sharpened blade to produce a dense cover with a deep root system.  Taller grass has deeper roots that draw moisture from a larger volume of soil and results in less need for irrigation. Taller grass shades the ground and reduces heat stress from high soil temperature. Two and a half inches is often recommended as a height for Kentucky bluegrass, but I am seeing a sensible trend on commercial sites and expensive neighborhoods where lawns are being mowed at heights of 3.5 and 4 inches.
  • Water deep and infrequently.  Avoid the temptation to irrigate in the spring just to get the grass growing; allow it to green up naturally.  As summer progresses don’t water until the lawn is showing obvious signs of wilt, then water deeply and infrequently; one inch of water once a week.   Irrigated lawns that do not experience brief periods of wilt are being over watered and produce shorter root systems that are not able to withstand drought and city enforced water restrictions.

 

Conserve water by knowing when to water

  • The best time to water a lawn is from 6 to 8 a.m. when disruption of the water pattern from wind is low and water lost to the atmosphere by evaporation is negligible.  Watering early in the morning also has the advantage of reducing the chance of turf diseases that require extended periods of leaf moisture.  Avoid irrigation during midday and windy conditions.
  • Move sprinklers frequently enough to avoid puddles and runoff.  Difficult-to-wet areas such as slopes, thatched turf, and hard soils may benefit from application of a wetting agent to improve surface penetration of water.
  • Water only when the plant tells you to.  Become familiar with areas of the lawn that wilt first (blue/purple leaves, rolled leaves, foot printing).  Water within 3 days of observing these symptoms.
  • Water problem areas by hand to postpone the need for irrigation of the entire lawn.  Some areas of a lawn usually wilt before others.  These areas, or “hot spots”, may be caused by hard soils that take up water slowly, slopes, southern exposures, and warmer areas next to drives and walks.  Lawns that have unusual shapes also may require some hand watering to avoid unnecessary watering of paved surfaces, mulched beds and buildings.  Soaker hoses that have a narrow pattern and supply water at a slow rate may be useful in these areas.
  • As an alternative, allow the lawn to go dormant by not watering.  Apply and inch of water per month to dormant cool season grass lawns during prolonged drought to avoid substantial turf loss.
     

Fig 1. An irrigated lawn on the left in stark contrast to a non-irrigated lawn on the right that is nearing complete dormancy.

Fig 2. A good example of deep and infrequent irrigation and beneficial wilting.  Irrigated lawn that is properly allowed to wilt before next watering.  Notice the down spout area that remains green (top left).  Front yard showing foot printing and beneficial wilting (top right).  Same lawn a week after irrigation showing rapid recovery and no injury from wilting (bottom left).

 

Fig 3. Lawn mown 4 inches tall (top right) and allowed to wilt between automatic irrigation cycles (top and bottom left).

Fig 4.  Lawn without irrigation allowed to go dormant. Picture taken 7-19-12 (left). Same lawn showing 25 to 50% of the lawn dead on 9-1-12 after rain and recovery (right).

Fig 5. Picture taken 8-7-12 from dormant Kentucky bluegrass lawn showing plant on left with a live bud and some green tissue and plant on right with crown and basal buds completely dead.  Dormancy is a plant mechanism that explains how a plant can turn brown from lack of water and potentially recover from basal buds, crowns, and rhizomes when water returns.  However, dormant plants under continued drought can eventually die.

Fig 6. Pictures of September lawns that did not recover from dormancy after rainfall or lawn watering occurred. 

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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. 

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Unusual September Weeds and Diseases in Iowa

September 24, 2013

With last week’s abnormally warm September weather, several diseases and weeds were discovered around the state of Iowa. Brown patch thrived with night temperatures above 70F⁰ coupled with high humidity. Brown patch is caused by the fungal organism Rhizoctonia solani. Damage affects the leaf blade from the tip down and is usually noticed in grasses which receive high amounts of nitrogen fertilization. Symptoms are straw colored irregularly shaped foliar lesions with a brown boarder. R. Solani can attack most cool-season grasses, but is most commonly noticed on creeping bentgrass greens, tall fescue lawns and Kentucky bluegrass.

Symptoms on bentgrass putting greens appear as a copper/gray-colored “smoke rings” ranging from a few inches to several feet where mycelium can be seen. Figure 1 below was taken last week by Dan Strey at the ISU research station. Figure 2 is from University of Missouri Extension IPM: Identification and management of turfgrass disease - looking at leaf and sheath lesions of brown patch.  

 

Figure 1: Brown Patch at ISU research station
Figure 2: University of Missouri publication looking at tall fescue foliar syptoms of brown patch

 

There are many fungicides that provide brown patch control such as Daconil, Banner Maxx, Heritage, and several others. Cultural practices such as reducing nitrogen levels and preventing long periods of wet conditions can reduce disease pressure. With temperatures tapering off over the weekend, hopefully it will be the end to the high temperature summer diseases in Iowa.

Oddly enough, in the middle of September we have also seen crabgrass and goosegrass seedlings germinating at the ISU research farm. Normal crabgrass germination occurs in mid-April to mid-May depending on your location in the state. Crabgrass is easily identified with fine hairs on the leaves and sheaths as well as its distinctive “protruding fingers” seedheads. Crabgrass also has a rolled vernation, while goosegrass has a folder vernation. 

Goosegrass is often mistaken for crabgrass and some people incorrectly refer to it as “silver crabgrass” because if it’s silvery appearance of the lower sheaths.  Goosegrass generally germinates 2-3 weeks later than crabgrass in the spring. The seed stalks of goosegrass also appear somewhat like a zipper with two individual seeds protruding in two directions. In figure 3 and 4 below you will see the side by side comparison from the Scotts grass manual.

Figure 3 and 4: Goosegrass and Crabgrass comparison from Scotts grass manual

Goosegrass is very difficult to control, even with the use of preemergence herbicides. The best postemergence option is a nonselective herbicide such as glyphosate. Optimal crabgrass postemergence control is obtained when applied while the crabgrass is small and actively growing. The use of fenoxyprop, quinclorac, and dithiopyr are the best options.

 

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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

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