Reducing brown ring patch severity on Poa annua greens
Brown ring patch is similar to other Rhizoctonia diseases, but does not react the same way to fungicides.
Steven J. McDonald, M.S.; Richard Grala and Bruce B. Clarke, Ph.D.
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We have conducted joint research studies on the management of
brown ring patch since 2010. From a field research perspective, this disease
has been challenging to work with because it is difficult to find naturally infected
putting greens with uniform disease incidence and severity. The main body of
research presented in this paper comes from work conducted in 2010 and 2011 on a
putting green in New Jersey that exhibited an unusually uniform distribution of
brown ring patch symptoms. Additional data were obtained in 2012 and 2013 from
smaller research trials on putting greens in Pennsylvania with less severe
disease pressure. Brown ring patch has become an important disease of annual
bluegrass (Poa annua) putting greens in the Northeastern region of the United States
since 2007 (6).
Symptoms of brown ring patch start as
small yellow rings with green grass in the center and can ultimately reach a
few feet in diameter. The yellow rings can turn an orange or brown color as the
disease progresses, and the pathogen may eventually kill affected turf.
Photos by Steve McDonald
ring patch is caused by Waitea circinata var. circinata (sometimes referred to by its asexual stage Rhizoctonia circinata
circinata) and is a serious
disease of short-mowed annual bluegrass turf throughout much of the cool, humid
regions of the United States. In New Jersey and much of the mid-Atlantic and
Northeast regions, this disease is often observed from early spring — when
annual bluegrass is breaking dormancy — through late spring. However, in cooler
regions, it can be a problem during the summer when air temperatures range from
65 F to 95 F (18 C to 35 C). Although the same pathogen can also significantly
damage roughstalk bluegrass (P. trivialis) and creeping bentgrass (Agrostis stolonifera) (4,6), our research
with this disease was conducted exclusively on annual bluegrass.
of brown ring patch start as small yellow rings (0.25-2 inches [0.635-5 centimeters]
wide) with green grass in the center and can ultimately reach a few feet (>0.5
meter) in diameter. The yellow rings can turn an orange or brown color as the
disease progresses and, in some cases, the pathogen may eventually kill
affected turf. After a severe outbreak, the rings may be sunken, are extremely
slow to heal and can adversely affect golf ball roll. In addition, rings of
this disease often appear as a series of smaller interconnected crescents,
rather than the fairly circular rings typically observed with yellow patch (Rhizoctonia cereale), a pattern that
can often be used in the field to distinguish between these similar diseases.
of the destructive nature of brown ring patch, superintendents usually resort
to frequent fungicide applications to manage it. In previous research, brown
ring patch efficacy data from California, Virginia and Illinois demonstrated
that there was variation in fungicide control depending on the number of
applications made and whether treatments were applied on a preventive or
curative basis (2). There have also been laboratory studies evaluating
fungicide effectiveness, but few field fungicide efficacy trials have been reported
in the northeastern United States. Furthermore, since brown ring patch has only
recently been recognized as a disease of annual bluegrass turf, limited data
are available about the impact of preventive and curative fungicide
applications or the impact of post-application irrigation on fungicide
performance. Because the pathogen survives in the lower canopy and thatch,
fungicide placement may also affect disease control.
†Each fungicide was applied as curative (C) or preventive (P) in each trial year.
Table 1. Fungicides tested (in alphabetical order), their active ingredients and fungicide groups, and research sites.
in California investigated the impact of nitrogen fertilizer source and the
vegetative suppressant Primo MAXX (trinexapac-ethyl, Syngenta) on the severity of
brown ring patch (5). Their research indicated that increasing fertilizer
inputs (from 0.5 to 1.0 pound nitrogen/1,000 square feet [2.4 to 4.8
grams/square meter]) reduced the severity of brown ring patch, although this has
not typically been the case with other Rhizoctonia diseases (3). Moreover, Primo MAXX (5 fluid
ounces/acre [0.365 liter/ hectare]) applied alone appeared to slightly increase
disease severity when compared to the water control, but the combination of Primo
MAXX and nitrogen fertilizers had no significant effect on the disease when compared
to nitrogen applications alone (5). There have been no reports, however, on the
impact of other plant growth regulators (PGRs) — such as Proxy (ethephon,
Bayer) or Embark (mefluidide, PBI-Gordon), which are commonly used in spring to
suppress annual bluegrass seedheads on greens — on this disease.
course superintendents maintaining predominately annual bluegrass putting greens
generally apply either Embark or a tank mixture of Proxy and Primo MAXX before
seedhead formation is visible (in the “boot” stage). This stage can be
identified by examining the base of the stems of annual bluegrass for swelling
or bulging. A change in the stem base indicates that seedheads have begun to
form. Seedhead suppressants are most effective when applied just before or at
the time of swelling (1). Applying these PGRs several days after swelling has
occurred or when seedheads are visible is generally less effective (1). Field
observations suggest that outbreaks of brown ring patch may be enhanced by
applications of these products; however, there are currently no reports in the literature
to support this hypothesis.
objectives of our research were to evaluate classes of fungicides commonly used
on turf for their ability to control brown ring patch on a preventive or
curative basis, to assess the impact of post-application irrigation on
fungicide efficacy and to determine the impact of selected PGRs on disease
severity. Two fungicides, Velista (penthiopyrad, Syngenta) and Secure
(fluazinam, Syngenta), were still experimental materials when they were
evaluated in our studies. Velista, which belongs to the carboxamide (succinate
dehydrogenase inhibitor; SDHI) class of fungicides, is expected to reach the
turfgrass market in 2014; and Secure, a contact fungicide, was brought to
market in 2012. Both of these chemistries provide good to excellent control of
brown patch (caused by Rhizoctonia solani), but their effect on brown ring patch has only
recently been evaluated.
2010, 2011 and 2013 fungicide trials
materials and methods
the fungicides, active ingredients, fungicide groups, manufacturers and
application timings used in this study are outlined in Table 1. Our two main
brown ring patch fungicide trials were conducted on the 11th green of the
Meadow Course at Fiddlers Elbow Country Club in Bedminster, N.J. Turf consisted
of a mixed annual bluegrass and creeping bentgrass (70:30, respectively) putting
green mowed at 0.125 inch (3.2 millimeters) five days per week with a triplex reel
mower. Extremely severe and uniform symptoms of brown ring patch had been
observed on this green for approximately six years before our study, even
though the superintendent had applied fungicides for control. Our treatments
were applied in a water carrier volume of 2 gallons/1,000 square feet (81.5
milliliters/square meter) using a CO2- pressurized boom at 38 psi (262 kpa)
with 8008 EVS flat-fan nozzles. Treatment rates and application dates are shown
in Tables 2 and 3. Plots were 5 feet × 5 feet (1.5 meters × 1.5 meters) and
were replicated four times in a randomized complete block design. A different location
of the green was used for each study. Plots were visually rated for percent symptomatic
turf on a scale of 0% to 100%, where 0 = no symptoms and 100 = entire plot area
blighted. Disease control was considered commercially acceptable if less than
5% of the turf area was blighted.
†Percent plot area blighted by brown ring patch was rated on a scale of 0%-100%, where 0 = no disease and 100 = entire plot area blighted.
‡Means followed by the same letter are not significantly different from one another. Means were separated using Tukey’s HSD test, P = 0.05.
Table 3. Impact of preventive and curative fungicide applications on brown ring patch disease on a predominantly annual bluegrass putting green at Fiddlers Elbow Country Club,
Bedminster, N.J., 2011.
Methods specific to the 2010 curative
fungicide efficacy study
entire green was treated with the PGR (seedhead suppressant) Embark at 22.5
fluid ounces/acre (1.64 liters/hectare) on April 2 and 3 (total of 45 fluid
ounces/acre [3.28 liters/ hectare]). All fungicide treatments were applied once
to a dry canopy on April 8, 2010.
curative fungicide results
ring patch severity was low (<10%) at the initiation of the study, but the disease
was uniformly distributed throughout the trial area. It’s important to note
that the objective was to evaluate the effect of a single “early-curative”
fungicide application on this disease. Most fungicides slowly reduced symptom
severity over the study period, but no treatments provided complete control. On
April 16 (8 days after application), there were no significant differences between
treated and untreated plots (Table 2). By April 28 (20 days after application),
only plots treated with Heritage TL (azoxystrobin, Syngenta) had less brown
ring patch than the untreated control. Disease severity peaked (35% turf area
affected) on May 7. On that date, all treatments, except Banner MAXX
(propiconazole, Syngenta), Endorse (polyoxin-D, Arysta), and Daconil Ultrex (chlorothalonil,
Syngenta), exhibited reduced disease severity compared to untreated turf.
However, only Heritage TL provided acceptable control (<5% disease severity)
by the end of the study.
specific to the 2011 efficacy study
treatments were initiated on March 22 and were reapplied on April 11 and 25.
Curative treatments were applied once (April 25) when there was 18% to 33% brown
ring patch present and were therefore considered “late-curative” (rescue)
treatments. The entire green was treated with Embark TO for annual bluegrass
seedhead suppression in mid-April at the label rate.
preventive fungicide results
initially appeared on April 11 as orange-yellow to brown rings, 0.5-2 inches (1.3-5
centimeters) in width, and eventually ranged from 3 inches to 2 feet (7.6-61
centimeters) in diameter. Data representing the impact of preventive and
curative fungicide treatments on brown ring patch are presented in Table 3. No
fungicide treatments provided complete control of brown ring patch, due to the
severity of the disease epidemic.
ring patch severity peaked in this trial on May 11 at 52% turf area affected
following a period of cool, humid and overcast weather. Turf receiving
preventive fungicide treatments typically had significantly less brown ring
patch than the untreated control, but this was not the case for most of the
curative treatments. Preventive fungicide treatments that provided acceptable
disease control throughout the study included Affirm (polyoxin-D,
Cleary/Nufarm); Chipco Triton Flo (triticonazole, Bayer); Heritage TL;
Medallion (fludioxonil, Syngenta); and Prostar (flutolanil, Bayer); as well as
tank mixtures of Torque (tebuconazole, Cleary/ Nufarm) + Affirm; and Velista +
Heritage. Preventive treatments that had the highest levels of disease (that
is, disease severity equivalent to the untreated control) were: Chipco 26GT
(iprodione, Bayer); Chipco Signature (Aluminum-tris, Bayer); Cleary 3336
(thiophanate-methyl, Cleary/Nufarm); and Secure. From this study, it was
apparent that, although these fungicides are useful for controlling other
turfgrass diseases, they should not be used alone where brown ring patch
pressure is high. It should also be noted that some of the fungicides in this
study were not labeled for the control of brown ring patch and therefore were
not expected to suppress this disease, but we felt it important to assess the
disease suppressive activity of as many commonly used turfgrass fungicides as possible
in this study.
curative fungicide summary
curative treatments provided acceptable control of this disease (<5% turf
area infected), presumably due to the severity of the epidemic, the late timing
of the curative treatments and the fact that only one application was made
after symptoms appeared on April 11.
the level of curative brown ring patch control in this trial was generally fair
to poor (8% to 52% turf area blighted), Affirm, Heritage TL, Medallion and
Torque had significantly less disease than untreated turf on the majority of
the rating dates. It’s important to note that disease severity of turf treated
with late-curative applications of Banner MAXX, Cleary 3336, Chipco 26GT, Chipco
Signature, Daconil Ultrex, Pentathlon (mancozeb, SePRO), Secure or Tartan was
equivalent to the untreated control. Therefore, as previously mentioned, such fungicides
should not be relied on as standalone treatments, especially when brown ring patch
specific to the 2013 efficacy study
Following the completion of our trials, we saw a greening response in areas that had been severely blighted. This symptom is likely due to a breakdown of organic matter (thatch) and a release of nitrogen and other nutrients resulting in enhanced greening that could be confused with Type II fairy rings.
additional curative field trial was conducted in 2013 on an annual bluegrass
research green located in Boyertown, Pa. Treatments were applied on April 25
and May 9 using the methods previously described for our 2010 and 2011
fungicide trials. The site was treated with Primo MAXX at (5 fluid ounces/acre
[0.365 liter/hectare]) every 14 days from April 25 throughout the duration of
the trial. Turf was mowed at 0.125 inch (3.2 millimeters) five days per week
with a Toro Flex 21 hand-reel mower. Disease severity was assessed (pre- and
post-treatment) as percent turf area blighted by brown ring patch using the
methods previously described for our 2010 and 2011 trials. Disease control was
considered commercially acceptable if less than 5% of the turf area was
2013 trial included two pre-mixed fungicides that were not included in our 2011
study — Briskway (azoxystrobin + difenoconazole; Syngenta) and Headway
(azoxystrobin + propiconazole; Syngenta) — and were compared to Medallion as
well as Heritage TL, which, in our 2010 and 2011 trials, had proven to be
effective when applied on a curative basis. Treatment No./name† Rate/1,000 square
curative fungicide summary
treatments were initiated on April 25 when brown ring patch was evenly
dispersed throughout the study (7% to 10% disease), and there were no
differences among the plots (Table 4). By May 1, all treatments reduced brown
ring patch compared to the non-treated control (21% turf area infected).
ring patch severity decreased in untreated turf after May 1 with the onset of warmer
air temperatures and, by May 15, complete control was observed for all
fungicide treatments. Brown ring patch severity was moderate in this trial (7%
to 21% in untreated turf). The data indicated that all of the fungicides tested
(Briskway, Headway, Medallion SC and Heritage TL) provided acceptable disease
when applied twice on a curative basis under moderate disease pressure.
Fungicide suggestions for the management of
brown ring patch
knowledge, the 2011 trial reported here is the first to evaluate a broad range
of fungicide chemistries commonly available in the turfgrass market for both
preventive and curative control of brown ring patch. These data confirm
previous research showing that fungicides such as Affirm, Heritage, Medallion and
ProStar, which are known to be effective against other Rhizoctonia diseases, also
provide high levels of brown ring patch control (2). Briskway and Headway are
pre-mixed fungicides that contain a DMI (difenoconazole and propiconazole,
respectively) combined with azoxystrobin (the active ingredient in Heritage TL).
Our data from 2013 indicate that these pre-mixes are as effective as Heritage
for the control of this disease when applied curatively under moderate disease
Post-application irrigation and efficacy of
curative fungicide treatments, 2011
Annual bluegrass growing in the aerification holes from the previous autumn was seemingly unaffected by brown ring patch. This could be due to several reasons, but less organic matter and improved turf quality are likely two factors.
the most effective fungicides in our 2011 trial, representing two different chemical
classes, were selected to evaluate the effect of post-treatment irrigation on
curative control of brown ring patch. Heritage TL (2 fluid ounces/1,000 square
feet [0.64 milliliter/square meter]) and Chipco Triton Flo (0.75 fluid
ounce/1,000 square feet [0.24 milliliter/square meter]) were applied once
curatively on April 25. The study was arranged as a split-plot design (each
plot had an irrigated and non-irrigated half) with four replications. Water
(0.15 inch [3.81 millimeters]) was supplied to the irrigated half of each plot
immediately following fungicide application (within 5 minutes) using a watering
irrigation improved brown ring patch control on turf treated with Chipco Triton
Flo, but not Heritage TL (data not shown). Although these results are
informative and suggest that post-treatment irrigation may improve brown ring
patch control for some fungicide chemistries, additional research is needed
before definitive statements can be made since only two products were evaluated
for one year in this small pilot study.
Additional field observations
brown ring patch was severe in our trials, a significant degradation of thatch occurred
(visual observations), especially in untreated plots. Following the completion
of our trials, we also saw a greening response in areas that had been severely
blighted. This has previously been reported (6) and is shown in the photo. This
symptom is likely due to a breakdown of organic matter (thatch) and a release
of nitrogen and other nutrients resulting in enhanced greening that could be confused
with Type II fairy rings (dark green stimulated turf in a circular patch).
Fungicide applications targeting these fairy ringlike symptoms would likely
have no effect if the patches were caused by brown ring patch. Another
interesting field observation was that annual bluegrass growing in the
aerification holes from the previous autumn was seemingly unaffected by brown
ring patch. This could possibly be due to deeper rooting in the aerification
holes resulting in improved plant health or because fertilizer had collected in
these areas and enhanced turf vigor. It is apparent from this observation that
further research is needed to determine the impact of aerification and rooting
on brown ring patch.
Effect of spring applications of PGRs on
disease severity, 2012
All PGR treatments resulted in better turfgrass quality when compared to the untreated control (data not shown). In the plots where seedheads were suppressed, turf remained a dark green color, and ball roll would likely have been more uniform.
small trial was conducted on the same putting green at Fiddlers Elbow Country
Club as our 2010 and 2011 fungicide trials, but in a different quadrant of the
green. The PGRs Primo MAXX (5 fluid ounces/acre [0.365 liter/hectare]), Proxy
(217.8 fluid ounces/ acre [15.9 liters/acre]), Primo (5 fluid ounces/ acre) +
Proxy (217.8 fluid ounces/acre), and Embark (22 fluid ounces/acre [1.6
liters/hectare]) were evaluated for their effect on brown ring patch and
seedheads, in comparison to an untreated control, at early spring application timings
and rates typically used on golf courses throughout the Northeast. All
treatments were applied on March 20 and April 5, 2012, and turf was maintained
as described in our 2011 fungicide efficacy study above. This trial did not
receive applications of any other PGR or fungicide treatments in spring 2012.
PGR treatments resulted in better turfgrass quality when compared to the
untreated control (data not shown). This was primarily due to increased
seedhead formation on untreated turf resulting in a whitish- brown color that
lowered visual quality estimates. Embark, Proxy alone and Primo + Proxy
treatments reduced seedheads compared to untreated and Primo-treated turf on
the majority of rating dates in this study (data not shown). In the plots where
seedheads were suppressed, turf remained a dark green color, and ball roll
would likely have been more uniform.
all PGRs in this study except Proxy alone exhibited “numerically” more brown
ring patch (greater disease severity) than untreated turf, only turf treated
with Proxy + Primo had significantly more disease than the untreated control on
one rating date (data not shown). These data suggest that PGR treatments that
provide a high level of annual bluegrass seedhead and foliar growth suppression
during spring may intensify brown ring patch disease on annual bluegrass
putting greens. However, since this study was only conducted for one year,
additional research is needed before this theory can be confirmed.
Integrated management of brown ring patch
ring patch is a unique turfgrass disease that does not respond to management and
environmental conditions in the same way as other diseases caused by Rhizoctonia. Historically, many
of cool-season turf have been associated with high levels of fertility and are
not known to be affected by PGRs (3). Brown ring patch thrives under a wide
range of temperatures that, in some regions, can be present from March through
November. Our observation that turf in aerification holes was less affected by
this disease confirms some previous reports suggesting that the amount of
thatch, organic matter and compaction may play a role in disease severity and
should realize that maintaining greens under conditions of low nitrogen fertility
and aggressive PGR use (high rates and/or short application intervals) to
enhance playability may lead to enhanced disease pressure and an increased
reliance on fungicides to manage brown ring patch on annual bluegrass greens.
Therefore, when environmental conditions favor disease development, less
aggressive PGR use — as well as adequate irrigation, nitrogen fertility and
fungicide applications — should be used to reduce the potential for severe
brown ring patch epidemics.
PGRs are being used to suppress seedheads in early spring and the course has
had a history of this disease, it would be prudent to make preventive
applications of one of the fungicides found to be effective in this and other
studies. Since fungicides are still strongly relied on for brown ring patch
management, selection of effective products is important because many of the
fungicides commonly used on golf courses are not effective against this
disease. Moreover, if brown ring patch becomes active, superintendents should not
expect rapid symptom remission because research has shown that it typically
takes 14-21 days or more for significant recovery to occur. Repeated fungicide
applications on a 14-day interval and increased nitrogen applications will aid
in recovery if conditions remain conducive for disease development.
thank Fiddlers Elbow Country Club for the space and flexibility to conduct
these trials on greens that remained in-play for the duration of the trials. We
also thank Bayer, BASF, Cleary/Nufarm, DuPont, PBI-Gordon, SePRO and Syngenta
for providing product and support for these trials.
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- Smiley, R.W., P.H. Dernoeden and B.B. Clarke. 2005. Compendium of Turfgrass
Diseases. 3rd ed. APS Press, St. Paul, Minn.
- Toda, T., T. Mushika, T. Hayakawa et al. 2005. Brown ring patch: A new disease
on bentgrass caused by Waitea circinata var. circinata. Plant Disease 89:536-542.
- Wong, F.P., C. Chen and L. Stowell. 2009. Effects of nitrogen and Primo MAXX on
brown ring patch development. Golf Course Management 77(5):117-121.
- Wong, F.P., and J.E. Kaminski. 2007 A new Rhizoctonia disease of
bluegrass putting greens. Golf Course Management 75(9):98-103.
StevenMcDonald is the founder of Turfgrass
Disease Solutions LLC, Spring City, Pa., and an instructor in the Professional
Golf Turf Program at Rutgers University. Richard Grala is a senior field
technician with Turfgrass Disease Solutions LLC. Bruce Clarke is the director
of the Rutgers Center for Turfgrass Science and chairman of the department of
plant biology and pathology and a 2014 recipient of GCSAA’s Col. John Morley
Distinguished Service Award.