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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


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. 


Ascochyta Wheel Tracking Syndrome

June 11, 2012

Dave Minner, Iowa State University
Craig Longnecker, Perficut Lawn & Landscape

Summer wheeling tracking by mowers has once again been sighted in Iowa. The picture sent to me by Kreg Longnecker from Perficut on 25 May shows wheel track injury to an irrigated lawn in Des Moines. A week of extremely dry and windy conditions caused some pockets of turf wilting to occur and preceded the turf injury symptoms. There is no way of predicting the type of year we will have but late May through June is the time we usually see this disorder. The wheel tracking associated with Ascochyta or drought/heat stress is unrelated to product application by lawn care companies. Follow the links at the end of this article for previous updates and pictures related to this problem in both 2010 and 2011. We have been able to isolate the fungus Ascochyta from lawns showing symptoms of tan/bleached leaves in both wheel tracked areas and injured lawns without wheel tracks. This is important information but we are still not sure how the fungus, dry stress conditions, and tire tracking all fits together in terms of making recommendations to reduce turf injury.

What we know

  • The symptoms have been reported late May through June in 2010, 2011, and 2012. 
  • Depending on the severity of injury and post injury growing conditions, damaged areas will take from 2 to 4 weeks to recover. Recovered lawns can be reinjured throughout the summer if conditions favorable for injury reoccur. 
  • Symptoms can occur without prior wilt but usually moderate wilt precedes injury, especially wheel tracking symptoms. 
  • Symptoms are bleached tan to white upper leaves with some leaf tips collapsed (see links below for several descriptive pictures of the problem). 
  • The problem is more frequently observed in newer subdivisions where lawns are less than 10 years old. Lawns in older mature landscapes, especially with large shade trees, seldom show this problem. 
  • The problem seems to be more problematic on Kentucky bluegrass, moderate on perennial ryegrass, and seldom occurs on tall fescue. 
  • The symptoms of wheel tire streaking associated with Ascochyta or drought/heat stress should not be confused with fertilizer burn or pesticide phytotoxicity.  

What we don’t know

  • There is a lot we don’t know about this disorder. Here are some of my observations and internal questions that I still struggle with. You can help me by sending pictures, information and opinions describing this problem. My phone and email contact is at the end of the article. 


  • In most cases the best looking lawns in the neighborhood seem to express the most severe injury. Lawns with automatic irrigation and higher fertility may express more injury. 
  • Iowa sod produces produce excellent quality sod, however many lawns in new subdivisions have been sodded on very poor quality subsoil using newer varieties of Kentucky bluegrass. Your comments related to the role that sod, age of lawn, soil quality, and grass variety play is needed. 
  • While we have isolated Ascochyta from injured plants we are still trying to determine if the problem is more related to the fungus or more associated to a direct injury caused by wheel stress on wilted turf. You can help by sending samples to the ISU Plant and Insect Diagnostic Clinic to confirm presence or absence of Ascochyta when these symptoms are observed. The cost for disease identification is $20. 

Plant and Insect Diagnostic Clinic
327 Bessey Hall
Iowa State University
Ames, IA 50011-3140 USA
Phone 515-294-0581

Recommendations at this time

  • The recommendations are a work in progress since research information is lacking on Ascochyta and wheel tracking. 


  • Mow taller to reduce wilt stress and less frequent to reduce the number of events when injury could occur.
  • Fungicides are not recommended at this time because of the uncertain role that Ascochyta plays in the disorder and the unpredictability of disease occurrence. We are however making preventative fungicide applications from late May through June 2012 in areas where the problem repeatedly occurs to help us determine the role that Ascochyta plays in wheel tracking. 

David D. Minner, Professor
Extension Turfgrass Specialist
Horticulture Department
Ames, IA 50011
(o) 515.294.5726
(c) 515.231.1741
(f) 515.294.0730


Tall Fescue Summer Performance

June 13, 2017

The last couple of weeks have been especially hard on lawns, athletic fields, and golf courses in parts of Iowa that have experienced high temperatures, drying winds, and a lack of moisture. Ideally turfgrass would receive around 1 to 1.25 inches of rain per week to stay actively growing. That has not been the case in many parts of Iowa. Kentucky bluegrass will go dormant to avoid the drought and will go off color. If the dry conditions persist, some turfgrass cover loss will be expected. Our research area is no different, we have several athletic field research plots which have not received adequate rainfall. The area's which were planted to tall fescue are still green and looking good. Another plot that looks good in these hot dry conditions is the HGT bluegrass plots. The pictures below are a good illustration of differences between turfgrasses on the same site and soil. Hopefully rainfall and cooler temperatures will bring relief for turfgrass in Iowa.  

Green tall fescue clumps in dormant Kentucky bluegrass
Picture 1. Green tall fescue clumps growing in heat stressed and dormant Kentucky bluegrass.

Green tall fescue turfgrass on the right of the picture and dormant Kentucky bluegrass turf on the left
Picture 2. Overhead shot of dormant Kentucky bluegrass (on the right) next to green and actively growing 'Revolution' tall fescue at the Iowa State Horticulture Research Station. 

Heat tolerant bluegrass is still green
Photo 3. Heat tolerant bluegrass maintaining a green appearance without irrigation at the Iowa State Horticulture Research Station in Ames.


Healthy turfgrass around a broken irrigation head
Photo 4. Healthy and unstressed turfgrass growing in a ring around a broken irrigation head.



August 15, 2017

Thiis has been a very dry year in parts of Iowa and lawns have been suffering.  Today is the 15th of August, and I have mown my own lawn once in the last 12 weeks and that was to kill the ragweed and trees that were growing in it.  I am now getting several calls from people with dry lawns, they mostly center around the following questions?


The answer is yes if you had Kentucky bluegrass. Kentucky bluegrass has an underground rhizome system that allows it to come back from extended drought periods.  The worst drought that we have had in the last 40 years was 1988.  Kentucky bluegrass came back fine in the fall after a drought that lasted from early May to mid-September.  If you have dead spots, reseed them with a good Kentucky bluegrass blend.


I recommend that you fertilize in August.  I plan to fertilize in the next week.  When the lawns do come back, the fertilizer will help with recovery.  One pound of nitrogen per 1000 sq ft in mid-August would be money well spent.  If the rains come and we get some recovery in the next few weeks, follow that up in about a month with another 1 lb of N/1000.  If the fall is dry, do not put on the additional application.  Wait until spring and apply some fertilizer with your preemergence herbicide at that time.  A preemergence herbicide will be very important next spring because the thinner lawns will likely be more prone to crabgrass next year.


I would wait on the postemergence broadleaf control application until October.  You can even do it in November.  There will be weeds like dandelion germinating during the recovery period of the lawns and it is best to wait and hit them late in the season.


If you have received some rain and the lawn is recovering, core aeration would be a good idea.  I would schedule that for a couple of weeks after the fertilizer application.

I predict that we will get rain again and that most lawns in Iowa will recover fine.  If you do need to do some seeding of dead areas, the best time is between August 15 and the end of September.  For more information on all subjects concerning lawn care, see the Iowa State University extension page at and go to the “publications” section.


The two lawns below are typical of the type of drought damage that has taken place in Iowa this summer.




This is what the rhizomes of Kentucky bluegrass look like.  The can survive extensive droughts.



November 26, 2013

I have been experimenting with tall fescue in various situations.  In the fall of 2012, following the serious drought that we had that year, I planted tall fescue in various parts of my lawn where I had lost Kentucky bluegrass during the drought.  This included areas on my septic mound where the soil was thin and on an area above my buried propane tank.

I had mixed results with that experiment.  We had another drought in 2013 that lasted from late June to October.  I went a full 90 days without mowing non-irrigated areas.  While some of the tall fescue did survive on the septic mound, some of it did not.  On the thin soil over the propane tank, I lost the tall fescue late in the 2013 season.  In a few other drought affected areas in my lawn, the tall fescue did survive the drought.

Tall fescue clearly stays green longer in droughts than does either Kentucky bluegrass or perennial ryegrass.  The picture below was taken at the research station in August of 2013 during the peak of this year’s drought.  The foreground is dormant Kentucky bluegrass.  The tall fescue is in the background and it remained green through much of the drought.

In this picture, there is tall fescue surrounding our perennial ryegrass cultivar study.  All of the ryegrass is nearly dormant, whereas the tall fescue around the outer edge of the trial remained green weeks longer.  

 I have also been noticing something else interesting about tall fescue late this fall.  While seedling tall fescue has remained green well into the fall, mature tall fescue has gone off color earlier that either the Kentucky bluegrass or the perennial ryegrass at the research station.  I have also noticed this on other mature tall fescue areas around Ames.  HaS anyone else noticed the tall fescue going off-color earlier than usual this year?

The light brown area on the right is tall fescue and the green areas surrounding the tall fescue are Kentucky bluegrass.



October 17, 2013

The recovery of Kentucky bluegrass following this summers drought has been amazing.  Most areas that were completely dormant in September have now recovered.  The reason for this is the rhizome system of this amazing lawn species.  The picture below shows this underground stem system and how it grows from the plant.  The rhizome is a stem and not a root.  It has buds on every node and every bud is a reproductive structure.   These buds are protected underground and can remain inactive for months.  When they are needed for the survival of the plant, the will begin to grow and form new crowns.

 Here is one of my pictures of the rhizome system on Kentucky bluegrass.  It has been estimated that one Kentucky bluegrass plant can produce as many as 1300 daughter plants in a single season, mostly from the rhizome system.

 Here are some interesting pictures that I took at the research station late in the summer and through the fall showing the ability of Kentucky bluegrass to recover.  The first picture shows an area around an irrigation repair where plywood was left on the Kentucky bluegrass turf long enough to kill all of the plants above ground.  It looks dead.

Here is a picture taken a couple of weeks later.  Notice how some green is beginning to appear.  That is regrowth from the underground stem system.

Approximately 4 weeks after the plywood was removed, the area is showing considerable improvement without any reseeding.

 This picture was taken in October.  It shows almost complete recovery.  This is the same type of recovery that we are seeing from drought affected areas this fall.  It is one of the main reasons that we use Kentucky bluegrass the way that we do in turf industry.




September 13, 2013

Here is a post from John Temme, Superintendent of Wakonda Country Club in Des Moines.  It was originally sent to his membership.

John's contact information is:
John Temme
Wakonda Club
1400 Park Ave.
Des Moines, IA 50321-1846
United States
Phone: (515) 255-5898
Fax: (515) 698-9810



Managing Water in Drought Conditions

Thank you for your patience and understanding while we manage the turf during the extreme heat. 


Water management for golf course turf varies when you consider what soil and turf type is present in each area.  At Wakonda Club, my two assistants (Jim and Shawn) and I are constantly monitoring weather patterns, soil types, and turf needs to apply water when needed.


We wanted to provide you with some interesting facts on how we create a beautiful golf course, even when mother nature is not cooperating.


·         Greens – Our new A1/A4 greens are very heat and moisture tolerant, meaning they hold up exceptionally well in dry/hot weather.


·         Tees – Our tees are built on a sand base so they drain really well; therefore, requiring more water than the fairways and greens.


·         Fairways – We have a nice stand of Penn Eagle II/Penn Links II bent grass with some Poa annua mixed in. “Poa” is a shallow rooted plant that cannot withstand high temperatures and no rain. So, to keep this plant alive during hot, dry conditions, we water more frequently resulting in softer fairways at times – especially in the valleys.



·         This season we are monitoring turf moisture with the help of the TDR 300 moisture meter – this device gives us a volumetric moisture reading in the soil.   We use this data to set up the irrigation system each night.


·         The irrigation system is run by a series of computer programs  that control over 800 irrigation heads on the golf course.  Each head is set to run different, for example, the hills receive more water than the valleys.   This system is very sophisticated but not perfect. 

·         This year we have implemented the use of soil wetting agents on tees and fairways.  This product helps the soil absorb moisture more evenly and has helped us produce better playing conditions.


·          To date, we are using 60,000 gallons less water/ day compared to last year under similar environmental conditions.


Thank You,

John and Fiona


#1 Fairway in 2012


#1 Fairway in 2013.





April 10, 2013

Here are some interesting pictures from Rob Elder of Omaha Organics showing the impact of the drought this spring on Omaha lawns.  Damage this bad is a problem for the lawn care people.  You will have to spring seed, but that means that you cannot put down a standard preemergence herbicide.  These spring seedings generally turn to crabgrass and other annual weeds by midsummer. You can use siduron, which will allow bluegrass and ryegrass to emerge and give you some relief from the annual weeds.  If you are planting straight Kentucky bluegrass, Tenacity (mesotrione) can help with the annual weed problem.  However, both methods are expensive and difficult to do in a commercial operation.

I suspect that these area were primarily perennial ryegrass before the drought.  This is what we are seeing in our area.  The bluegrass lawns came back pretty well after the drought because of their rhizome system underground.  Whereas perennial rye thinned out and stayed that way.

Hopefully we will get more moisture this year and return to more normal conditions for the Midwest.



April 5, 2013

I have had a couple of contacts on grass that was dormant seeded in the fall beginning to emerge in late March and early April.

The first one is from Rob Elder of Omaha Organics in Omaha.  He seeded some areas in drought damaged areas in November of last year in Omaha.  The picture below is from March 27.  In this situation, they did not rake the area first, they just put the tall fescue seed on the bare areas and covered them with compost.

The second picture is from Larry Ginger of American Lawn care in Des Moines.  The picture is from March 31 and shows emerging tall fescue.

Here is Larry's description of the process that he used.

  1. Late August:   Sprayed Roundup Pro at a 10% rate twice (2 days in a row) trying to kill exsisting wide-bladed tall fescue.
  2. During the week of Thanksgiving, 2012:
    1. Mowed the dead grass very short and dispersed the clippings to surrounding areas.
    2. Applied grass seed.
    3. Core aerated the areas 5 to 8 times.
    4. Waited one day for the cores to dry up.
    5. Then dragged the areas with a section of chain link fence.
    6. Then crossed my fingers wondering if the dormant seeding would emerge in the spring.

I dormant seeded about 10,000 sqaure feet around our place, and most areas are not showing new seedlings yet.  But it's very early, especially with the below normal March temperatures.

I seeded with "Enduro" turf-type tall fescue.  (Six Point, Five Point, and Falcon IV) 

Tall Fescue Seed 

As many of you know, I have never been a very big fan of dormant seeding.  I generally recommend that you keep the seed on the shelf until spring and seed when it is warm enough for germination.  The reason for this is the high mortality rate of seed applied in the fall.  While I am still concerned about dormant seeding of Kentucky bluegrass in the fall, I may change my mind on dormant seeding tall fescue into these damaged areas in lawns.  We will see how these establishments go this spring.

Dr. Minner is planning a longer article for the blog on this subject in the next few weeks.