• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.161-164
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• 2010

Dollar spot, caused by Sclerotinia homoeocarpa F.T. Bennett, is the most economically important turfgrass disease on golf courses in North America due to its persistent nature. Fungicides, plant growth regulators, and other products were evaluated for preventative control of dollar spot and the secondary effects on brown patch and Pythium in a mixed stand of creeping bentgrass and annual bluegrass golf course putting green. Most fungicides provided excellent control of dollar spot throughout the trial but Rhapsody alone did not provide adequate control. Civitas applied alone and tank-mixed with Banner MAXX(R) and Daconil Ultrex(R) provided acceptable control throughout the study. No phytotoxicity was observed on any of the treatments applied but a darker green color and reduction in turfgrass growth was observed in a treatment with plant growth regulator, Trimmit. Treatments that contained Civitas and the Civitas Harmonizer also exhibited green pigmentation.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.43-47
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• 2011

Creeping bentgrass (Agrosis stolonifera L.) is regarded to be the most widely used cool-season turf grass species grown on golf greens and fairways in temperate climates of North America. Creeping bentgrass is highly susceptible to the fungal disease 'dollar spot' caused by Sclerotinia homoeocarpa. Dollar spot is a foliar disease favored by conditions of high humidity, warm days, and cool nights. Studies using Aliette Signature (Fosetyl Aluminum formulated with a green pigment) mixed with another broad-spectrum fungicide do not always provide additional visual quality benefits compared to the fungicide alone. The exact mechanism for improved summer visual quality, when it occurs, is not known. Fertility management and environment likely contribute. The object of this study is to evaluate fungicide strategies for control of dollar spot and effect on visual quality during summer and on an L-93/G-2 creeping bentgrass green. Nine fungicide combinations were used for this study. Disease control and visual quality by fungicides was evaluated on an established G-2/L-93 creeping bentgrass green at 3-hole Sunshine Golf Course in Lemont, IL. All fungicide combination showed excellent dollar spot suppression except Fore throughout the study. Visual quality of greens by addition of Aliette Signature is enhanced when bentgrass growth is compromised and slow. Dollar spot levels in Fore plots increased to 30% on 14 August, and was no different than untreated plots. Unacceptable quality by Fore was due to lack of dollar spot control.

• Weed & Turfgrass Science
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• v.7 no.2
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• pp.158-165
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• 2018

This study was conducted to evaluate the control efficacy of dollar spot on creeping bentgrass after applying various amounts of tebuconazole, chlorothalonil and mixture of tebuconazole and chlorothalonil (tebuconazole+chlorothalonil). In effect of three fungicides on suppression against Sclerotinia homoeocarpa, tebuconazole and tebuconazole+chlorothalonil were found to inhibit more than 98% fungus growth on medium and 70% in chlorothalonil treatment. The control efficacy of tebuconazole at different rates of 31.25, 62.5, and $125a.i.\;mg\;m^{-2}$ on creeping bentgrass showed more than 80%. Application of tebuconazole ($125.0a.i.\;mg\;m^{-2}$), tebuconazole+chlorothalonil ($125.0a.i.\;mg\;m^{-2}+135.9a.i.\;mg\;m^{-2}$) and chlorothalonil ($135.9a.i.\;mg\;m^{-2}$) were suppressed 96%, 80%, 70% for the dollar spot severity, respectively. Correlation between application amount of fungicides and control efficacy of dollar spot was significantly positive, and suggested amount of tebuconazole, tebuconazole+chlorothalonil and chlorothalonil that might suppress more than 80% of dollar spot were calculated to 29.6, 132.2+142.8, and $157.0a.i.\;mg\;m^{-2}$, respectively.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.191-201
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• 2006

Dollar spot caused by Sclerotinia homeocarpa is one of major diseases in putting greens. Microorganisms antagonistic to S. homeocarpa, a pathogen of dollar spot, were primarily screened through in vitro tests, including dual culture method and triple layer agar diffusion method. In vivo tests were also conducted to select the best candidate for a biocontrol microorganism, using pot experiment. Bacillus subtilis EW42-1 and Trichoderma harziaum GBF-0208 were finally selected as biocontrol agents against dollar spot. Relative Performance Index(RPI) was used as a criterion of selecting potential biocontrol agents. B. subtilis EW42-1 and T. harzianum GBF-0208 showed resistance to several agrochemicals mainly used in a golf course. B. subtilis EW42-1 and T. harzianum GBF-0208 suppressed effectively the disease progress of dollar spot like synthetic fungicide tebuconazole in the nursery where dollar spot had seriously occurred. B. subtilis EW42-1 and T. harzianum GBF-0208 have a potential to be biocontrol agents for the control of dollar spot.

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.96-101
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• 2012

Dollar spot caused by Sclerotinia homoeocarpa F.T. Benn. is a common and economically important turfgrass disease in South Korea. Fungicides were evaluated for control of dollar spot in creeping bentgrass golf course putting green. Commercial formulations of propiconazole, thiophanate-methyl, chlorothalonil, trifloxystrobin and boscalid were applied to plots of creeping bentgrass, each of the latter four fungicides was tank mixed with propiconazole at the same rates, and applied as treatments. The dollar spot severity in the nontreated plots of field A and B progressed toward peak diseases of 18.3 and 66.7% from 10 or 15 days after inoculation, respectively. Significant differences were detected among control values of the fungicides. Dollar spot control provided by boscalid was significantly greater than the other fungicides which showed low control values in a higher disease condition. No synergistic interactions, except propiconazole + thiophanate-methyl treated plot, were detected under a lower disease pressure. However, under a higher disease pressure, synergism was observed at all fungicide combinations, except a propiconazole and boscalid tank mixture. These data suggest turfgrass managers in golf course can take advantage of fungicide synergism to control dollar spot using the products and rates in this study.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.376-382
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• 2015

Dollar spot, caused by Sclerotinia homoeocarpa, is the major disease in cool-season turfgrasses. Understanding the distribution of this pathogen in soil and thatch is important to developing disease control strategies. In this study, toothpicks were used to detect S. homoeocarpa in the turfgrass canopy, thatch, and soil at different distances from dollar spot infection centers. The effect of penetrant and contact fungicide applications with different water volumes on distribution of S. homoeocarpa was also investigated. S. homoeocarpa was detected in 100% of samples taken from the leaf canopy, 83.3% in thatch area, and 0% in the soil from within the infection center. S. homoeocarpa was isolated in 100% of samples taken from the edge of the infection center, but was only detected in 13% of the samples taken at 1.5 cm away from the infection center edge. S. homoeocarpa was isolated at a higher frequency in the propiconazole treated plots than those treated with chlorothalonil and was not detected in leaf canopy samples when either fungicides was applied with 6.78 L of water. In conclusion, the toothpick-aided detection technique has improved our understanding of S. homoeocarpa epidemiology and could be used as a diagnostic tool to detect for fungicide resistance on golf courses.

• Weed & Turfgrass Science
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• v.7 no.2
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• pp.87-97
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• 2018

Turfgrass provides various beneficial effects to our societies such as recreation, aesthetic components, and other public service. Diseases in turfgrass is the major issue, which cause quality problems in golf courses, playgrounds, parks and cultivation areas, and tremendous cost is required to prevent the diseases. Research activity and investigation for turfgrass disease remain to be further attributed when compared to other crops in Korea. In this study, we present previously reported turfgrass diseases researches, especially caused by fungal pathogens, and review the history of turfgrass research activity in Korea to contribute future turfgrass research direction. Research papers were searched and analyzed using Korea Educational and Research Information Service (www.riss.kr). More than eighty papers presented turfgrass diseases and among the papers, 50% were published in Korean Journal of Turfgrass. Half of the papers reported turfgrass diseases control. Research articles about large patch disease were the majority (36%), followed dollar spot (18%), Pythium blight (10%) and Typhular blight (8%). Number of the first disease reports in Korea were total fifteen. Total 542 fungicides have been registered in Korea to prevent turfgrass diseases and most of the fungicides were for brown patch, rust, yellow patch, dollar spot, snow mold, summer patch, anthracnose, Pythium blight, powdery mildew and algae. And we will also need to conduct ecological studies on turf diseases and to develop control methods with improved efficacy and environmentally-friend sound. Researches on epidemiology of turfgrass diseases which deals with the incidence, distribution, and interactions with other factors will be also greatly favored for precise control prescription, timing of control and use of less pesticides.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.248-254
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• 2010

To define the optimum conditions for the mass production of four antifungal Pseudomonas spp. isolated from soil, we have investigated culture conditions and effects of various nutrient sources on the bacterial growth and evaluated antagonistic activity against Rhizoctonia solani and Sclerotinia homoeocarpa, plant pathogens. The optimum temperature and pH for the growth of these isolates were determined as pH 7.0 and $20^{\circ}$ or $25^{\circ}C$, respectively. Sucrose, tryptone, and $K_2HPO_4$ generally were more adequate for better growth as carbon, nitrogen and mineral source, respectively. The nutrient sources were also found to be very effective for high antifungal activities against R. solani and S. homoeocarpa. It was elucidated that YUD-F group (P. mandelii and P. fluorescens), which inhabit regions at relatively low temperature, had more broad spectrum and higher antifungal activity than YUD-O group (P. trivialis and P. jessenii) generally against R. solani and S. homoeocarpa. It is thought that the differences of the average temperature in the various habitats of Pseudomonas spp. influence the optimal growth temperature and antifungal activity. Especially, Pseudomonas spp. of YUD-O group showed the better antifungal activity against dollar spot caused by S. homoeocarpa, but showed relatively weaker antifungal activity against brown patch caused by R. solani.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.408-412
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• 2013

Dollar spot caused by Sclerotinia homoeocarpa F.T. Benn. is a common and economically important turfgrass disease in South Korea. Fungicides mixture (propiconazole 25% + boscalid 47%) treatments, showing synergistic interaction, with three application rates (low: 50.3 ml $10a^{-1}$ and 97.5 g $10a^{-1}$, intermediate: 67.0 ml $10a^{-1}$ and 130.0 g $10a^{-1}$, and high: 100.5 ml $10a^{-1}$ and 195.0 g $10a^{-1}$) and two application intervals (10 and 15 days) were evaluated for control of dollar spot in creeping bentgrass golf course putting green. In both nontreated plots of field A and B, the disease has severed as 48.3 and 60.0% after the pathogen inoculation. Two fungicide mixture treatments showed significantly higher the disease control effect than a single fungicide treatment (propiconazole). Field A which showed more the disease severity but the fungicide still showed acceptable level of the disease efficacy (89.0%), significant differences in control value were not detected among treatments. The results suggest that the lower application rate of two fungicides mixture treatments may reduce the dollar spot disease severity in creeping bentgrass golf course putting green.

• Weed & Turfgrass Science
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• v.3 no.2
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• pp.121-129
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• 2014

We investigated turfgrass diseases and inoculum density at nationwide turfgrass cultivation sites in year of 2013. Occurrences of large patch and rust disease appeared in September. Brown patch recorded in September to October at Namhea and Pythium blight disease occurred outbreaks in early July at Namhea site. Some sites in Namhea damaged 3% area of total cultivation field by Sclerotinia homoeocarp. In Daepyeong (Gyeongnam), Fairy ring and large patch were recorded. Severe takeall and fairy ring have been observed in Gochang-si. Multi-site in Cheongju-si, brown patch was observed in pandemic level. Interesting enough, a cool-season turfgrass cultivate sites in Pyeongtaek-si brown patch, leaf blast, summer patch, and Curvularia leaf spot were investigated during the surveys period. Inoculum densities (Rhizoctonia spp.) at turfgrass cultivations sites were increased as cumulatively in all survey sites. The investigation result indicated that the disease occurrence and pathogens are similar as diseases in golf courses.