Microdochium Patch Research Articles

Iron Sulfate and Phosphorous Acid Affect Turfgrass Surface pH and Microdochium Patch Severity on Annual Bluegrass.

Microdochium patch is a turfgrass disease caused by the fungal pathogen Microdochium nivale. Iron sulfate heptahydrate (FeSO4•7H2O) and phosphorous acid (H3PO3) applications have previously been shown to suppress Microdochium patch on annual bluegrass putting greens when applied alone, although either disease suppression was inadequate or turfgrass quality was reduced from the applications. A field experiment was conducted in Corvallis, Oregon, U.S.A., to evaluate the combined effects of FeSO4•7H2O and H3PO3 on Microdochium patch suppression and annual bluegrass quality. The results of this work suggest that the addition of 3.7 kg H3PO3 ha-1 with 24 or 49 kg FeSO4•7H2O ha-1 applied every 2 weeks improved the suppression of Microdochium patch without substantially compromising turf quality, which occurred when 98 kg FeSO4•7H2O ha-1 was applied with or without H3PO3. Spray suspensions reduced the pH of the water carrier, therefore two additional growth chamber experiments were conducted to better understand the effects of these treatments on leaf surface pH and Microdochium patch suppression. On the application date in the first growth chamber experiment, at least a 19% leaf surface pH reduction was observed compared with the well water control when FeSO4•7H2O was applied alone. When 3.7 kg H3PO3 ha-1 was combined with FeSO4•7H2O, regardless of the rate, the leaf surface pH was reduced by at least 34%. The second growth chamber experiment determined that sulfuric acid (H2SO4) at a 0.5% spray solution rate was always in the group that produced the lowest annual bluegrass leaf surface pH, but did not suppress Microdochium patch. Together, these results suggest that while treatments decrease leaf surface pH, this decrease in pH is not responsible for the suppression of Microdochium patch.

Seed mixtures of red fescue and colonial, creeping, or velvet bentgrass for pesticide‐free management of Nordic golf greens

AbstractThis research aimed to determine if creeping bentgrass (Agrostis stolonifera L.) can be used as an alternative to colonial bentgrass (Agrostis capillaris L.) in a mixture with red fescue [equal rates of Chewings fescue (Festuca rubra ssp. commutata Gaud.) and slender creeping red fescue (Festuca rubra ssp. littoralis [G. Mey.] Auquier)] on Nordic golf greens managed without pesticides. The two mixtures were compared in two experiments: Experiment 1 under the creeping bentgrass management regime (mowing height, 3 mm; fertilization, 15 g N m−2 yr−1) and Experiment 2 under the red fescue management regime (5 mm and 10 g N m−2 yr−1) at three sites during 2015–2018. A seed mixture of red fescue and velvet bentgrass (Agrostis canina L.) was included in Experiment 2 only. The results showed that red fescue plus creeping bentgrass produced greens of equal turfgrass quality and with less Microdochium patch than red fescue plus colonial bentgrass under both regimes. In Experiment 2, red fescue plus velvet bentgrass resulted in higher turfgrass quality than the other mixtures but was more susceptible to Microdochium patch than red fescue plus creeping bentgrass. Tiller counts in the mixed plots at Landvik showed that red fescue was not outcompeted by bentgrass in any of the mixtures and that it was easier to manipulate the balance between red fescue and bentgrass in the mixture with creeping bentgrass than that with colonial bentgrass. More research should be put into optimal management, especially irrigation and thatch control, of mixed red fescue–bentgrass greens.

Resistance to the demethylation‐inhibiting fungicide propiconazole in Canadian populations of Microdochium nivale

AbstractTurfgrass managers have anecdotally reported decreased efficacy of DMI fungicides for the control of Microdochium patch and pink snow mold at golf courses in British Columbia, Canada. Isolates of Microdochium nivale from these locations, along with isolates collected in Ontario, Canada, were tested for their sensitivity to the fungicide propiconazole [1‐([2‐(2,4‐dichlorophenyl)‐4‐propyl‐1,3‐dioxolan‐2‐yl]methyl)‐1,2,4‐triazole]. Ontario isolates (47) had values for effective concentration causing 50% growth inhibition (EC50) ranging from <0.001 to 0.89 µg ml–1. In comparison, British Columbia isolates (50) had an EC50 range of 0.02 to 8.7 µg ml–1. Sensitivity testing with a discriminatory concentration (0.1 µg ml–1) of a larger set of isolates revealed that 24% of Ontario isolates (43 of 181) and 77% of British Columbia isolates (55 of 71) exhibited resistance to propiconazole (>50% growth on 0.1 µg ml–1 compared to non‐amended media). Because of the cool, wet climate of coastal British Columbia, turfgrass managers use more applications of fungicides annually, including propiconazole, to control diseases caused by M. nivale, and this has resulted in a greater proportion of isolates being resistant to propiconazole. In contrast, Ontario has a less favorable climate for these diseases, with accordingly fewer fungicide applications directed toward this pathogen and hence less risk of fungicide resistance developing.

Poa trivialis, Lolium perenne or Poa annua as nurse crops for faster establishment of Agrostis stolonifera putting greens in Nordic climates

AbstractSeed mixtures with a nurse grass that germinates quickly at low soil temperatures can be an option for faster establishment of Agrostis stolonifera (AS) putting greens after winter damage. From 2015 to 2018 Poa trivialis (PT) ‘Dark Horse’ and Lolium perenne (LP) ‘Chardin’ were evaluated as nurse grasses in comparison with pure AS ‘Independence’ at two experimental sites in each of the two major climatic zones of the Nordic countries. Poa annua (PA) ‘Two‐Putt’ was also included as a nurse grass in the northern zone. As an overall trend, establishment was faster with AS+LP than with AS+PT and AS+PA, which both had faster establishment than pure AS. In the northern zone, AS+PT produced better turf quality than pure AS in the seeding year and year after and tended to be superior even on average for the entire trial period (mean value 6.0 versus 5.8 for pure AS, 5.3 for AS+LP, and 4.6 for AS+PA; scale 1–9 where 9 is the highest quality). Within the same zone, AS+PT also suffered less overall winter damage than the other combinations and was less infected with microdochium patch than pure AS. In the southern zone, PT and especially LP were far more persistent than in the northern zone and compromised turfgrass quality compared with pure AS. In conclusion, we recommend PT as a nurse grass for faster establishment of AS putting in the northern zone, but not in the southern zone where AS should rather be seeded in a pure stand.

Suppression of Microdochium patch using rotations of mineral oil, sulfur, and phosphorous acid

AbstractMicrodochium patch is a turfgrass disease caused by the fungal pathogen Microdochium nivale (Fr.) Samuels and I.C. Hallett that occurs in cool, humid conditions, which are commonplace in the U.S. Pacific Northwest and northern Europe. Pesticide restrictions in certain areas make suppressing Microdochium patch challenging, and alternative control methods are desired. Previous research has shown that mineral oil, S, and phosphorous acid (H3PO3) suppress Microdochium patch, but abiotic damage was associated with repeated mineral oil applications. Two field experiments in western Oregon focusing on the suppression of Microdochium patch and turfgrass quality on annual bluegrass (Poa annua L.) greens are presented. The first experiment compared tank mixtures of mineral oil and S or mineral oil and H3PO3 in rotation with a tank mixture of S and H3PO3. The second experiment focused on seasonal rotations that excluded mineral oil in certain months and compared 2‐ and 3‐wk application frequencies. All rotations, in both experiments, suppressed Microdochium patch compared to the non‐treated control, although differences in turfgrass quality were observed. In the first experiment, green cover percentage was used to assess abiotic damage. A mineral oil and H3PO3 tank mixture rotated every 2 wk with S and H3PO3 resulted in the highest green cover percentage. In the second experiment, most of the applications made every 2 wk completely suppressed Microdochium patch. Two treatments applied every 2 wk that withheld mineral oil in the winter months resulted in turfgrass quality ratings considered acceptable for putting greens on all rating dates.

Comparing rates of mineral oil, sulfur, and phosphorous acid on Microdochium patch suppression and turfgrass quality

AbstractMicrodochium patch is a turfgrass disease caused by the fungal pathogen Microdochium nivale (Fr.) Samuels and I.C. Hallett that occurs in climates similar to the cool, humid regions of North America's Pacific Northwest. Mineral oil, S, and phosphorous acid (H3PO3) have been shown to suppress Microdochium patch on annual bluegrass (Poa annua L.) putting greens in western Oregon. Previous research using rates of 19.9 kg mineral oil ha–1 applied every 2 wk alone or as a tank mixture with 12.2 kg S ha–1, 3.7 kg H3PO3 ha–1, or both resulted in unacceptable turfgrass thinning. The objective of this field experiment was to evaluate whether tank mixes of these products would suppress Microdochium patch and yield acceptable turfgrass quality when rates of mineral oil were reduced from 19.9 to 10.0 kg ha–1, S from 12.2 to 6.1 kg ha–1, or H3PO3 from 3.7 to 1.8 kg ha–1. In both years of the experiment, all treatments suppressed Microdochium patch to <2% disease compared to more than 40% disease in the non‐treated control. Mineral oil applied with S resulted in a larger loss of green cover compared to mineral oil applied with H3PO3 regardless of rate. These results suggest that tank mixing mineral oil and S should be avoided in the winter months. Further research studying the mitigation of green cover loss associated with these treatments is warranted.

Effects of nitrogen, phosphorus and potassium rates on Microdochium patch

AbstractResearch on nitrogen (N), phosphorus (P) and potassium (K) ratios have suggested that maintaining the proper balance of those nutrients is critical to disease mitigation. However, research on N, P, and K ratios relevant to annual bluegrass (Poa annua L.) and Microdochium patch (Microdochium nivale) is not available. The objective of this research was to evaluate the effects of winter‐applied N, P, and K rates in combination with sulfur and phosphorous acid on Microdochium patch development within an annual bluegrass putting green in the absence of traditional fungicides. Field research was conducted from October 2018 to April 2019 on a mature sand‐based annual bluegrass putting green. Factors included monthly applications of urea nitrogen (46–0–0) rate (4.9 kg N ha–1 and 9.8 kg N ha–1), phosphorus rate (0.0 kg P ha–1 and 1.22 kg P ha–1), and potassium rate (0.0 kg K ha–1 and 4.9 kg N ha–1). To avoid extreme disease levels, all of these treatments received monthly applications of phosphorous acid. When comparing nitrogen treatments across both rates vs. nitrogen combined with P, K or both, disease levels decreased from 9.9 percent (urea only) to 5.5 percent (urea with P, K, or both). Additionally, when nitrogen rates increased from 4.9 kg N ha–1 to 9.8 kg N ha–1, the percent disease decreased from 8.4 to 4.8 percent. Findings from this project suggest that applying nitrogen only as urea will lead to more Microdochium patch vs. applying urea with P, K, or both, and nitrogen applied at the higher rate will decrease Microdochium patch incidence.

Combinations of rolling, mineral oil, sulfur, and phosphorous acid affect Microdochium patch severity

AbstractMicrodochium patch is a turfgrass disease that occurs in cool, humid regions caused by the fungal pathogen Microdochium nivale (Fr.) Samuels & Hallett [Teleomorph = Monographella nivalis (Schaffnit) E. Müll]. Fungicide applications are the predominant method of control; however, pesticide restrictions have generated concern regarding the use of traditional chemicals to manage turfgrass pests. The objective of this research was to evaluate the effects of the cultural practice of rolling in combination with applications of mineral oil, S, and/or phosphorous acid (H3PO3) on the suppression of Microdochium patch on an annual bluegrass (Poa annua L.) putting green. A 2‐yr field trial took place from September 2013 to June 2014 and was repeated from September 2014 to June 2015 on a sand‐based annual bluegrass putting green in Corvallis, OR. Experimental design was a 2 × 4 × 2 × 2 randomized complete split‐plot design with four replications. Factors included rolling, the fertility products S and H3PO3 applied alone and in combination, mineral oil treatment, and year. Mineral oil suppressed Microdochium patch although applications led to turfgrass thinning. The combination of S and H3PO3 provided greater Microdochium patch disease suppression compared to applying either alone. Rolling also suppressed Microdochium patch in the second year of this study. Further research to determine how to best utilize these combined cultural practices to manage Microdochium patch is warranted.

The effects of iron sulfate heptahydrate water carrier volumes on Microdochium patch suppression and turfgrass quality

AbstractMicrodochium patch is a turfgrass disease caused by the fungal pathogen Microdochium nivale (Fries) Samuels & I.C. Hallett that occurs most commonly in cool‐humid regions such as the Pacific Northwest. Fungicide applications are the predominant method of controlling this disease, although alternatives to fungicides are desired in areas where pesticide restrictions occur. Previous research has shown that 97.6 kg FeSO4·7H2O ha−1 applied every 2 wk in 814 L ha−1 water carrier suppresses Microdochium patch; however, turfgrass thinning occurred. The objective of this trial was to determine if higher water carrier volumes would mitigate turfgrass thinning while still suppressing Microdochium patch. This field trial quantified the effects of four different water carrier volumes of 97.6 kg FeSO4·7H2O ha−1 applied every 2 wk on the suppression of Microdochium patch, percent green cover, and turfgrass quality of an annual bluegrass putting green in Western Oregon. This research demonstrated that 97.6 kg FeSO4·7H2O ha−1 applied every 2 wk suppressed Microdochium patch on annual bluegrass putting greens to equivalent levels regardless of water carrier volumes ranging from 1019 to 4075 L ha−1. Higher percent green cover was also observed when higher water carrier volumes (3056 or 4075 L ha−1) were used. While iron sulfate heptahydrate treatments suppressed Microdochium patch to less than one percent disease throughout the trial, no water carrier volume reduced annual bluegrass thinning enough to be considered acceptable for golf course putting greens.

Effects of rolling and N-fertilization on dollar spot and Microdochium patch on golf greens in Scandinavia

Dollar spot was officially documented in Scandinavia in 2013 and the spread and damage from this disease has increased during last years. In summer 2017, on the golf greens with red fescue (Vallda GC, Sweden) and with the mixture of red fescue, colonial bentgrass and annual bluegrass (Roskilde GC, Denmark) rolling 2 times per week reduced dollar spot 61% and 37% and rolling 4 times per week reduced dollar spot 95% and 54%, respectively. Thus, rolling 3-4 times per week can be recommended on golf greens with dollar spot pressure. In the experiment 2018 dollar spot was reduced 24% with increase in nitrogen from 150 to 240 kg ha-1 yr-1 on creeping bentgrass/annual bluegrass golf green (Kävlinge GK, Sweden). However, the increased N-rate lead to a higher degree Microdochium patch from 14% to 30%.

Potential of NanoPro to reduce fungicide rate for control ofMicrodochium nivaleon an annual bluegrass (Poa annua) green

This is a report on the potential of NanoPro™to reduce the rate of two commonly used fungicides for control of Microdochium patch (Microdochium nivale), the economically most important turfgrass disease in Scandinavia. The experiment was conducted from 14 Sept. 2018 to 1 May 2019 on an annual bluegrass golf green at the NIBIO Turfgrass Research Center Landvik. Use of NanoPro™at a rate of 292 ml/ha in tank mixture with the systemic fungicide Delaro® SC 325 or/and the contact fungicide Medallion® TL produced the same level of disease control with a 30-60% reduction in fungicide dosage as with full fungicide dosage without additive. NanoPro™was more effective with Medallion® TL than with Delaro® SC 325. We conclude that NanoPro™may have a big potential in Scandinavia and other countries where authorities require reduced fungicide use. The experiment should be repeated one more year before giving final recommendations.

A new leaf blight disease of turfgrasses caused by Microdochium poae, sp. nov.

ABSTRACTA novel species of Microdochium was identified as the causal agent of a leaf blight of Poa pratensis (Kentucky blue grass) and Agrostis stolonifera (Creeping bentgrasses), two cold-season turfgrasses widely grown on golf courses in northern China. This disease first appears as small, water-soaked, and scattered leaf spots. Under conditions of high temperatures and successive days of rain, the infected leaves rapidly lose their integrity and large diseased patches appear. Fungal strains were isolated from blighted leaf spots. A phylogenetic analysis based on the nuc rDNA internal transcribed spacer regions and 5.8S rRNA gene (ITS1-5.8S-ITS2 = ITS) and parts of the β-tubulin (TUB2) and RNA polymerase II second largest subunit (RPB2) genes strongly supported that these isolates are a distinct evolutionary lineage in Microdochium (Microdochiaceae, Xylariales) that represents a new taxonomic species, herein named as M. poae. Microscopic characters confirmed that these strains were morphologically distinct from known Microdochium species. The pathogenicity of M. poae was confirmed by inoculating spore suspension on both grasses and reisolation of the pathogen from symptomatic tissues. The optimal growth temperature suggests that the occurrence of the new leaf blight disease caused by M. poae was significantly different from the microdochium patch disease caused by M. nivale.

The Influence of Iron Sulfate Application Interval on the Suppression of Microdochium Patch on an Annual Bluegrass Research Green in Western Oregon

The Influence of Iron Sulfate Application Interval on the Suppression of Microdochium Patch on an Annual Bluegrass Research Green in Western Oregon

Effects of Sulfur and Calcium Source on pH, Anthracnose Severity, and Microdochium Patch Management on Annual Bluegrass in Western Oregon

Core Ideas Increasing sulfur application rates reduced the number of fungicide applications required to manage Microdochium patch. Increasing sulfur application rates increased anthracnose severity. Calcium carbonate, calcium sulfate, and calcium phosphate did not have an effect on Microdochium patch or anthracnose severity.

Rolling and Biological Control Products Affect Microdochium Patch Severity on a Sand‐Based Annual Bluegrass Putting Green

Core Ideas There is evidence that rolling an annual bluegrass putting green 5 d a wk−1 resulted in a lower severity of Microdochium patch. Two biological control products were shown to significantly lower Microdochium patch severity. Neither biological products nor rolling were shown to completely suppress Microdochium patch; therefore, turfgrass quality was not considered acceptable for any treatments. This study offers evidence of alternative disease control techniques for the management of Microdochium patch on annual bluegrass putting greens. The turfgrass disease Microdochium patch caused by the pathogen Microdochium nivale (Fries) Samuels & I.C. Hallett occurs in cool, humid regions. Fungicide applications are the predominant control method, however increasing pesticide restrictions have generated concern regarding their use. The objective of this research was to evaluate the effects of rolling 5 d wk−1 in combination with three biological control products applied every 2 wk on Microdochium patch severity on an annual bluegrass (Poa annua L.) putting green in the absence of traditional fungicides. Biological control products included; BW136N (Trichoderma harzianum Rifai strain T‐22 + Trichoderma virens (J.H. Mill. Giddens & A.A. Foster) Arx strain G‐41), Rhapsody (Bacillus subtilis strain QST 713), and Provide (a microbial solution containing unspecified strains of Bacillus subtilis, Mucor hiemalis, and Trichoderma harzianum) + ReVive (7% humic acid derived from Leonardite). Rolling was effective at inhibiting Microdochium patch as measured by area under disease progress curves (AUDPC) in both years on rolled plots compared to not rolled plots by 47 and 75%, respectively. Applications of BW136N and Rhapsody reduced the severity of Microdochium patch as measured by AUDPC compared to the control (66 and 50% reduction, respectively). The ProVide + ReVive combination did not suppress disease in this study. At the peak of disease, turfgrass quality was greatest when rolling was combined with applications of BW136N or Rhapsody. These findings suggest that rolling as well as BW136N or Rhapsody can inhibit Microdochium patch severity and further research into this management method is warranted.

Evaluation of a Petroleum‐Derived Spray Oil for Control of Microdochium Patch and Turfgrass Spring Performance on Nordic Golf Greens

Core Ideas Mineral oil was as effective as or more effective than fungicides in controling Microdochium patch. Repeated applications of mineral oil in autumn might inhibit turfgrass green‐up in spring. Mineral oil can reduce conventional fungicide use on Nordic golf courses. Greenkeepers are looking for alternatives to fungicides for control of turfgrass diseases. Our objective was to evaluate a petroleum‐derived spray oil with a blue‐green pigment for control of Microdochium patch/pink snow mold (Microdochium nivale) on golf course putting greens with various durations of snow cover. The spray oil was applied at rates 27 or 54 L ha−1 every third week from late August or September to December, either alone, in tank mixture with potassium phosphite (3 kg PO3 ha−1) or in tank mixture with half rate of fungicides approved for turf, in five 1‐yr trials in the Nordic countries. The oil was as effective or more effective than fungicides and gave, on average, 94 and 98% disease control at rates 27 and 54 L ha−1, respectively. Tank mixtures with half rate of prochloraz + propioconazole and fludioxonil did not increase disease suppression in a trial with 79 d snow cover. Phosphite reduced disease severity in one trial only and did not improve disease control or turfgrass quality when tank‐mixed with the oil. The pigment in the spray oil was highly persistent and improved turfgrass greenness except in a trial where the combination of oil and ice cover gave a transitory black color at ice melt. Another trial with long snow cover showed a drop in turfgrass quality in spring as the spray oil prevented normal green‐up. In conclusion, this research shows that a spray oil has the potential to reduce fungicide use on Nordic golf courses.

A long term evaluation of differential potassium fertilization of a creeping bentgrass putting green

The objective of this research was to evaluate bentgrass quality, growth, and disease incidence over a range of soil and tissue potassium levels. ‘Penn A4’ creeping bentgrass (Agrostis stolonifera L.) on a sand root zone was maintained as a putting green. The treatments included four levels of liquid potassium sulfate, ranging from 0 to 249 kg ha−1 yr.−1 K and one level of granular gypsum at a rate of 100 kg ha−1 yr.−1 Ca. No differences in vegetative or quality parameters were observed over the 6 year study period. Tissue K, Mehlich-3 extractable K, and Microdochium patch infection were all affected by treatment, with high-K treatments being greater than control and Ca treatments in all three instances. Near-daily turfgrass harvest resulted in much greater K removal than was estimated to be available from the pools extracted by Mehlich-3 and 1 M HNO3, suggesting that K became plant-available from more recalcitrant pool. Traditional soil testing methods may be inadequate for determining plant-available K in sand root zones. Total soil K analysis of the 0-K treatment indicated an increase in K during the study period, likely as a result of regular additions of sand via topdressing. Weathering of mineral K likely provided sufficient K to compensate for the lack of fertilizer.

Resistance of Prairie Junegrass and Tufted Hairgrass Germplasm to Diseases Common in Temperate Low-Input Turfgrass Systems

Prairie junegrass and tufted hairgrass are two turfgrass species that are native to the United States and require less water, fertilizer, and pesticide compared with more commonly used turfgrass species such as Kentucky bluegrass. However, little is known about the resistance of these low-input turfgrasses to common turfgrass diseases. The primary objective of this research was to identify disease-resistant germplasm of both prairie junegrass and tufted hairgrass that can be used in future low-input turfgrass breeding efforts. A total of 41 populations of tufted hairgrass and 23 populations of prairie junegrass were evaluated for resistance to Microdochium patch, dollar spot, and rust development in a controlled environment. Genetic variation in disease resistance was clearly present in the unimproved germplasm of both prairie junegrass and tufted hairgrass, providing important direction for future breeding efforts that will allow wider implementation of low-input turfgrass species.

Reaction of Bentgrass Cultivars to a Resistance Activator and Elevated CO2 Levels When Challenged with Microdochium nivale, the Cause of Microdochium Patch

Climate change prediction models forecast increased CO2 levels and temperature changes. Microdochium nivale is a common pathogen of turfgrasses in temperate climates, and these changes may increase Microdochium patch disease severity. This research involved experiments on cultivars of Agrostis spp. and Poa annua inoculated with M. nivale and incubated under two CO2 concentrations. The efficacy of a resistance activator, Civitas + Harmonizer, was tested on eight cultivars that were grown under 400 or 800 ppm of CO2 during a 15°C/10°C (day/night), 16‐h photoperiod. The grasses were treated with water or Civitas + Harmonizer and inoculated 1 wk later with M. nivale. Disease severity was lower at 800 ppm than at 400 ppm of CO2, and the application of Civitas + Harmonizer decreased disease symptoms. This research will be useful for recommendations on turfgrass cultivars for northern temperate zone golf courses and on sustainable management practices to face the challenges of climate change.

Nitrogen and Iron Sulfate Affect Microdochium Patch Severity and Turf Quality on Annual Bluegrass Putting Greens

Microdochium patch is an important turfgrass disease in cool‐humid regions and is caused by the pathogen Microdochium nivale (Fries) Samuels & Hallett. Control of the pathogen is necessary to provide acceptable putting‐green‐quality turf, and fungicide applications are the predominant method of control. Increasing pesticide restrictions have generated interest in alternative management techniques of Microdochium patch. This research evaluated the effects of three nitrogen and five iron sulfate rates on Microdochium patch development on a trafficked, sand‐based, annual bluegrass (Poa annua L.) putting green in Corvallis, OR for over 2 yr in the absence of fungicides. Data included turf quality, area under disease progress curve, and soil test results of saturated paste extract pH, cation extractable sulfate, and DTPA‐sorbitol extractable iron. This research provided evidence that low rates of urea (4.88 kg N ha−1) applied every 2 wk did not lead to an increase in Microdochium patch severity and that iron sulfate applications decreased Microdochium patch on annual bluegrass putting greens. Despite the disease suppression observed, no treatment received a turf‐quality rating considered acceptable. Low turf‐quality ratings where disease development was low were attributed to turfgrass thinning or blackening of the shoots resulting from iron sulfate applications. Soil tests provided evidence that the highest iron sulfate level used in this study (97.65 kg ha−1) applied every 2 wk would likely lead to a lower soil pH and an increase in soil sulfate levels.