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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 tmcclellan@usga.org or (630) 340-5853 or Bud White at budwhite@usga.org or (972) 662-1138.

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
njdunlap@iastate.edu

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.

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.