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Food for Thought this Fall

November 2, 2009

USGA Green Section Mid-Continent Region

Food for Thought this Fall

By Ty McClellan, Agronomist

Updated October 19, 2009

The weather in 2009 for the upper Mid-Continent Region will be recorded as one of the coldest and remembered as one of the oddest. Other than a 12-day stretch of intense heat during mid-June, temperatures were well below normal. In fact, only a handful of days reached 90°F in the Chicago area and very few areas in the upper Mid-Continent Region hit 100°F. When elevated temperatures did develop, they were short-lived and/or quickly offset by cool nighttime temperatures. Rainfall was plentiful and often timely. All told, environmental conditions mimicked those of the Pacific Northwest rather than the Midwest.

Given these non-typical summer conditions, cool-season turfgrasses experienced much less stress while the warm-season turfgrasses lacked vigor, as their growth was slowed much of the year by cooler temperatures and frequent rainfall. For all turfgrasses, disease development was rather minor when compared to more typical summers. By all appearances, this was a relatively easy summer for turfgrasses and their managers; however, there were a number of shortfalls observed this year. Before falling victim to a false sense of security, areas needing special attention as we transition into fall are detailed below:

• Completion of Earlier Projects - One of the wettest springs on record for the upper Mid-Continent Region did not favor those in the midst of course projects earlier this year. Whether work was performed in-house or contracted out, projects were delayed, if not abandoned, as even two consecutive days of favorable weather proved elusive. On the other hand, growing conditions were quite favorable for cool-season turfgrass (especially in the rough) all year-long and, with frequent rainfall, additional labor was needed to keep up with mowing. This limited the availability of labor for course projects. More often than not, spring projects either did not get finished or they persisted into the primary golfing season, inconveniencing golfers and interfering with routine daily course maintenance.

Looking forward, projects that went uncompleted (particularly if critical) will need to be readdressed. To do so with the typical number of full-time employees may result in other delays, as the unfinished projects take precedence over those originally planned for this winter. In other words, without additional winter staff to get the schedule back on track, projects previously planned for this season may need to be postponed until the projects from last season are completed.

• Adequate Budgeting for Fungicides - Mild temperatures correlated to an overall reduction in disease outbreaks in 2009 and the amount spent on fungicides followed suit. Superintendents generally reported anywhere between a 15% and 35% reduction in fungicide use this year when compared to previous years. While courses can count themselves lucky this year (and maybe even last year), this year’s fungicide expense should not be used when establishing next year’s budget, since it was not a true indication of typical disease pressure or the subsequent budget needed for control. It will be important to keep in mind typical use and needs.

• Irrigation - Cool temperatures and timely rains for most of the golfing season meant much less irrigation than normal. In fact, many superintendents in the Chicago area reported using their irrigation systems less than five times during the entire year for the purposes of replenishing soil moisture to appropriate levels. Rather, most used irrigation to simply water in chemical applications or lightly syringe ‘hot’ spots. As such, this year was very kind to those with inadequate or poor irrigation systems, who pay for water, or who have poor quality irrigation water. Unfortunately, this has caused some to lose sight of the need to improve the irrigation system, accurately budget for future water use, or support additional practices to manage problems associated with poor water quality, such as increased aeration, flushing and applications of gypsum, lime, calcium, etc.

• Organic Matter Accumulation on Putting Greens - Organic matter in putting green root zones increased this year, even for those with well-designed sand topdressing and aeration programs. Soil temperatures simply remained too cool for much of the year and putting green root zones were oftentimes waterlogged given regular, if not record-setting rainfall. Basically, cool soil temperatures caused soil microbial activity to slow and thus, limited its ability to decompose organic matter. A wet spring also meant the soils remained very saturated, thus limiting oxygen levels in the root zone that slowed oxidation, i.e. natural aerobic decomposition, of organic matter. To further complicate matters, routine topdressing applications throughout the growing season were difficult to administer given frequent inclement weather, so less sand was applied less often. To account for the increase in organic matter accumulation, an even greater emphasis should be placed this fall and next spring on core aeration and incorporating more sand into putting green root zones.

• Poa annua Control – Given that this summer was more like that of the Pacific Northwest, overcast skies combined with cooler temperatures and frequent rains that created environmental conditions very favorable for Poa annua. As such, decreasing Poa annua populations found in creeping bentgrass putting greens and fairways was very difficult this year. A lack of mid-summer heat meant that the Poa annua did not decline, and selective herbicides, such as Velocity, or plant growth regulators with some known levels of Poa annua suppression, such as paclobutrazol (Trimmit) or flurprimidol (Cutless), were not as effective. Looking forward, greater success should be anticipated in the future with a return to more typical summer weather.

If you would like more information about a Turf Advisory Service visit, do not hesitate to contact either of the Mid-Continent regional offices: Ty McClellan at or (630) 340-5853 or Bud White at or (972) 662-1138.


Hard Year in Kansas City

July 10, 2009

Throughout the 2009 season, we have experienced lots of extremes, both in weather and disease. The year started out extremely warm in January through March, with soil temps reaching close to 60 degrees. This rise in temps fell off soon after aerification and remained throughout April and into May. Since then temperatures have soared and so has disease. There have been many cases and outbreaks of Pythium, Zeae, dollar spot, brown patch and red thread. The heaviest cases coming from June 15th through the 29th when we had days in the upper 90's and lows in the mid to upper 70's (Picture on right shows extensive tracking lines from golf carts that had heavy mycelium growth in the morning and were like this by night fall the same day. They were sprayed later that morning with mancozeb and banol and no more activity was seen).

With the heat came a great deal of humidity and disease. Soil temps reached over 98 degrees and stayed there for a good 10+ days damaging many roots and leaving the grasses susceptible to pythium and root rot. Some practices used both at my course (Royal Meadows) and several other courses in the area were the use of a pull-behind Planet Aire. This machine slices tear-drop size slits in the green with minimal surface damage but can go 6 inches deep, done in the same time as a greens mowing with golfers barely noticing. It allowed us to manage our root-zone and keep the damaging water and moisture under control. Many superintendents use solid tines or spikers, but the speed and efficiency of the Planet Aire is second to none, a highly recommended machine to add to your collection.

As we have moved into the typical hot and disease prone months of July and August, the courses with cool-season fairways will have some interesting chemical and fertilizer purchases. With revenues down and temperatures up many course managers need to slash budgets, even when we as superintendents need to increase our spending for these difficult months. Some successful practices that I have seen on Bent/Poa fairways in Kansas City are as follows:

- Calibration of equipment, correct nozzles (AIC 11010vs) and proper rates (50 gal/acre for fairways)

- Use of generic pesticides when applicable (typically have less time between sprays, weather and products not sticking to plants as well, but huge cost savings!) If you would like a list of products that we have field tested and found as the best generics email me at

- Stress fighters and Phosphites (control of pythium by building larger cell walls and improving plant health)

- Spot Spraying in low areas for Pythium and other water prone diseases (pre disease is best) instead of broad applications that are extremely expensive

- The use of contacts and systemics, with rotations of different modes of actions, chemistries and formulations at different times of the year

- Growth Regulators, both for seed head suppression in the Spring and restricted/controlled growth in certain times of the year

- Above all is always being aware of your golf course, knowing each and every trouble spot, watching water usages, remember a dry golf course is a lot better than seeing a solid cotton field of disease

If you have any questions concerning your spray rig set-up, fungicide timing, application rates or even our fungicide program at Royal Meadows please let me know. It is a tough world out there with all of us constantly balancing our budgets and beauty of our golf courses.

Mark Newton
General Manager & Course Superintendent
Royal Meadows Golf Course


Disease Review: Brown Patch

August 13, 2009


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




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

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




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

Nick Dunlap
GCSAA Campus Representative
Turfgrass Management
Iowa State University




Rust - To treat or not to treat

August 20, 2009

Rust occurs every year on Iowa turf but as a general rule fungicide applications are not necessary. This year may be the exception to that rule. Several calls with specific circumstances have led me to recommend fungicides for rust control. Before we get to the rest of the story let’s review the normal approach to dealing with rust. As diseases go, rust can be easily identified by the yellow to orange flecks that develop on leaves and stems. As the disease progresses orange and cinnamon colored blisters and pustules form. Clouds of spores can turn your shoes orange when walking through turf heavily infested with rust.

- Rust occurs on Kentucky bluegrass and perennial ryegrass, but we are even seeing it on tall fescue this year. Immature turf that was seeded in the spring or early summer has been especially impacted by rust this year.

- Rust is usually more severe in turf that is growing slowly. Low light intensity, inadequate fertilization (especially nitrogen), drought stress, and infrequent mowing encourage rust development. A little extra shot of nitrogen is usually all that is needed to stimulate leaf growth that allows mowing to remove infected tissue. The idea is to keep the grass growing fast enough so that grass clippings are generated each week. Sufficient nitrogen and irrigation are required to “out grow” the rate of rust infection. If the grass stays at the same height and mowing is not needed, then rust can eventually cover the entire plant.

- Excessive irrigation and irrigation practices that extend the period of free moisture on the leaf surface encourage rust. The best time to water is at dawn because the turf is usually already wet from dew. Avoid watering from 10 am through dusk, this only extends the period of leaf wetness. Night time irrigation, after dew has formed, would be the next best time for watering to reduce rust.

Hopefully most of you may not need to justify a fungicide application. Those of you with actively growing turf may not be experiencing severe rust problems as the summer season begins to wind down. Golf Course Superintendents may choose to accept some turf injury on lower priority areas such as golf course roughs with the expectation that recovery usually occurs later in the autumn. However, here are the circumstances from my university extension visits that have resulted in fungicide recommendations to control rust in 2009. Most of them involve athletic fields.

- Most of the calls have come during late July and early August so that only leaves about 30 days until the field will open for play. If we have extended conditions in September that favor rust infection, high traffic areas will quickly fade.

- Three calls had fields that were newly seeded in the spring and early summer. Germination and establishment were going quite well with the mild summer temperatures this year. However, the establishing grass did not have substantial vertical growth so when the rust hit, it quickly covered the entire plant and growth completely stopped. Four lbs of N per 1000 sq.ft. had already been used on the native soil field during establishment so the manager was reluctant to use more nitrogen that could incite other summer turf diseases such as brown patch and pythium. It is full of rust and they want to play football in 14 days. I recommended a fungicide and another pound of nitrogen. At a separate spring seeded field they were using a rain train to irrigate. It takes three 8-hr sets to irrigate the entire field so the rain train was running 24-7 for over a month. That also means that leaves were wet for too long because half of the water was being applied during the day time. The field was covered with rust and turf growth had stopped. I recommended a half pound of nitrogen per 1000 sq.ft., a rust control fungicide, and cutting back on irrigation by only watering for one 8-hr set during the night from 10pm to 6am.

- Another field had no means of irrigation and was intended for practice only. The worn field was over-seeded in May and the grass was establishing nicely with the mild summer, but again the new turf was stunted and covered with rust. For this field I recommended a pound of nitrogen per 1000 sq.ft., but did not recommend a fungicide. It just didn’t seem logical to apply fungicides when turf was not irrigated.

- Fungicide Treatments – It is unlikely that fungicides would reduce the blemishes on plants that were already infected. New growth is very important to recovery from existing rust. The fungicide applications were intended to reduce infection on new growth. Some of the fungicides that I recommended for this control strategy were: azoxystrobin (Heritage), chlorothalonil (Daconil Ultrex), propiconazole (Banner MAXX), and triadimefon (Bayleton).

It has been a peculiar year with little pressure from our typical turfgrass diseases. This year I found myself recommending fungicides to control, the normally non-destructive, rust on athletic fields where the disease pressure could have adversely impacted the football playing season.

Dave Minner



November 16, 2012

Last week, Spencer Nelson, one of our undergraduates, brought a picture to me of a disease on creeping bentgrass seedlings from the new Iowa State University Golf Performance Center south of Ames, IA.  The bent had been seeded approximately a month before the picture was taken.  The disease looked like Yellow Patch, a cool temperature disease caused by Rhizoctonia cerealis.   He took a sample to the Iowa State Plant Disease Clinic and had pathologist Erica Saalau-Rojas grow it out on agar plates. 

Erica was able to confirm that it was a Rhizoctonia organism, but was not able to confirm that it was cerealis.  It is highly likely that it is cerealis, given the time of year and the appearance of the patches on the turf.

I was in Chicago this week for a golf course superintendent's meeting at Medinah Country Club.  One of the subjects that came up at the meeting was that they are also seeing Yellow Patch on seedling bentgrass in the Chicago area.

Here is some information from Spencer on what he saw and what was applied to control the disease.

A patch disease has developed on seedling creeping bentgrass at the new Iowa State Golf Performance Center just south of Ames. The patches are showing up in bentgrass seedlings of four different cultivars in both USGA greens and native soil fairways. The 4 bentgrass cultivars are V-8, L-93, 007, and an Alpha/T-1 blend.  The patches are between six and twelve inches in diameter with a yellow border. The foliage inside the ring is mostly purple.

Initially the patches were small and yellow with little to no purple and were believed to be a fertility problem. As the patches grew a fungal problem became a more evident diagnosis. The second assumption was Yellow Patch, Rhizoctonia cerealis. Samples were taken to the ISU Pathology lab for identification. Before the results were back from the lab, the area was treated with Instrata(chlorothalonil, fludioxonil, and propiconazole). The pathology lab confirmed the diagnosis of Rhizoctonia spp.  

Figure 1.  Is the Yellow Patch symptoms as they appeared on November 7, 2012.


Figures 2 and 3 are microscopic pictures of the organism that was grown on agar media at the ISU Plant Disease Clinic.  The hyphae show the septa and the classic right angle branching with the pinched appearance at the right angle of a Rhizoctonia.




Sclerotium rolfsii Spotted at the ISU Horticulture Research Station

July 25, 2013

This spring, as you all know, brought large amounts of rainfall to central Iowa. This was a blessing for most including us the Horticulture Research Station. The water level in the pond returned to its maximum height, soil moisture reached great depths, and reduced the amount water needed to irrigate. The record breaking rainfalls also encouraged moss growth on one of our putting greens. Over the years, we have tried to encourage this growth to continue research on moss controls.

A couple of weeks ago, I noticed spots on the green that appeared to look like dollar spot, however, the spots were only covering the moss and not the bentgrass. I decided to leave the area untreated to see if these spots would continue to spread or remain localized. Within a few short weeks, the disease spread like wildfire across the moss. A sample was taken to the Disease Diagnostic Clinic here at Iowa State University. The pathogen was identified as Sclerotium rolfsii.


Sclerotium rolfsii is a fungal disease that has an extensive host range that targets over 500 species. It is very common in the tropics, subtropics, and other warm temperature regions. However, it is very rare to see the disease this far north. The pathogen rarely occurs when winter temperatures fall below 32˚F. The disease survives in the form of sclerotia. These sclerotia are easily spread by foot traffic and mowing equipment. Most of the research articles that I have read state that control is relatively difficult to achieve. We will continue to monitor the area and post any updates on the control.


Potential for Late-Season Pythium

August 29, 2013

With the Iowa temperatures expected to continue in the upper 90’s with high humidity for the foreseeable future, it presents conditions conducive to Pythium blight activity. Pythium is known as one of the most destructive turf diseases in the Midwest and overnight it can lead to large turf death. With most turf managers fungicide programs winding down for the year; it might be the time to have a bottle of Cyazofamid (Segway®) handy for a knockdown contact application. 

Pythium is a high temperature disease which presents the most damage under daytime temps in excess of 86⁰F, followed by nights in the high 60's. It usually affects close-mown turfgrass under intense management. Symptoms generally include small circular patches (1-2 inches) accompanied with a cotton-like mycelia that appears in the early morning. Pythium is often first noticed on sites with poor drainage. It is also easily spread by mechanical means and can be carried over turf by foot traffic and/or mowing equipment.  Reducing your nitrogen fertility inputs, avoiding night watering, increasing air movement, and improving areas with poor drainage reduces your threat for disease incidence.

Below are some pictures of the cotton-like mycelia seen in the early morning.


Summer Turf Diseases on Home Lawns

September 11, 2016

This past summer has been an exceptional year for diseases on turfgrass, and home lawns weren’t immune to these diseases either. Dr. Christian’s has mentioned several times this summer that this summer was the worst Brown Patch in Iowa he has seen in 30+ years. Summer temperatures often in the 80’s and lows in the upper 60’s with high humidity and rainfall made the conditions perfect for these summer diseases. The good news is that the temperatures seem to have cooled and repairs can be made to yards.

With the warm temperatures, ample rainfall, and high humidity this past summer, Iowa lawn’s endured prolonged periods of perfect weather conditions for brown patch (Rhizoctonia solani). This disease was noticed in Iowa from June on into September. It is often noticed as circular patches from a few inches to several feet.

Brown patch at the ISU Horticulture Research Station
Brown patch on creeping bentgrass putting greens at the Iowa State Horticulture Research Station.

The area in the patch can become killed and create a sunken patch, often though this disease will not completely kill the turf, but rather just thin those spots, which can recover with proper care after the weather conditions change. Brown patch lesions on leaves are easy to identify and are irregular tan or light brown in color with the edges of the lesions being a dark brown in color.

Brown patch lesions on turfgrass leaves
A close picture of brown patch lesions on turfgrass leaves.

Another problematic disease this summer was summer patch (Magnaporthe poae) which happens predominantly on Kentucky bluegrass and commonly occurs when temperatures are above 82. It is caused by a fungus that colonizes the roots. These patches often appear suddenly as small yellow patches, since the roots are affected, adding water will not help the declining turf health. As the grass dies it will turn a straw color. These patches often have areas inside of the patch that are not affected and seem healthy. Symptoms of summer patch will not be noticeable when the weather cools. Promoting healthy roots will help to minimize the impact of summer patch by regular aeration in the fall, mowing at proper mowing heights, and improving drainage in the yard.   

Disease on turfgrass lawn

If these diseases injured your turfgrass the fall is a great time to recover from them, as healthy turfgrass is the best way to combat weeds and disease next year. Make sure your yard is fertilized this fall, aeration each fall to improve gas exchanges to the roots and improve drainage making them healthier can help, follow proper mowing heights for the turfgrass species that are present in the yard, and overseed with more grass seed if large areas of dead turf exist.
Aerators can help improve drainage and promote healthy turf.
Aerators can help improve drainage and promote healthy turf.

One final note, several calls and emails this week have been related to people mistaking disease damage for chemical damage. Remember that typically disease damage will be patchy, while chemical damage would be a complete grass kill or in straight lines.  

Below are a couple pictures of disease damage on lawns from the Ames area:

Summer disease damage to a lawn in Ames


Turfgrass diseases can become a large problem is conditions exist for a long time.


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