First Report of Dollar Spot Caused by Sclerotinia homoeocarpa on Agrostis stolonifera in Argentina

During the summer of 2000, circular, yellow-to-brown, blighted, 2- to 4-cm-diameter patches were observed on creeping bentgrass (Agrostis stolonifera) putting greens (cv. Pennlinks) maintained at a 4- to 5-mm height on a golf course in Pilar (Buenos Aires, Argentina). Symptomatic leaves had transverse chlorotic bands that sometimes extended to the tip with brown lesions inside the bands. A fungus was isolated from symptomatic tissue after surface sterilization with 2% bleach for 1 min and plating on 2% potato dextrose agar (PDA). The mycelium was fluffy and white. The culture turned olive to brown and developed black stromata on the lower side of the plate base after 2 weeks. Pathogenicity tests were performed on 2-month-old healthy plants of A. stolonifera (cv. Crenshaw) grown in sterilized sand. Recently cut, 14-mm-diameter plugs of A. stolonifera were placed in 22- × 17-cm plastic trays filled with a sterilized mixture of 50:50 soil/sand (vol/vol). Plants were maintained at a 7-mm height. Two sources of inoculum were prepared; one was cultured on PDA at 22 to 25°C for 10 days and the other was prepared by incubating in sterilized soil at room temperature for 14 days. Twenty pieces of 1-cm-diameter agar blocks containing mycelium were placed in each plug at the base of the plants. In the infested soil inoculation, 25 g of soil were distributed among the plants on the substrate surface. Control plants were treated with either sterile PDA pieces or noninfested soil. The trays were irrigated with sterilized distilled water, covered with polyethylene bags, and kept in a controlled environment chamber at 25°C with 12 h per day of fluorescent light for 30 days. Leaf chlorosis appeared 7 and 10 days after inoculation for the agar-plug and infested-soil methods, respectively. Leaf necrosis was observed at day 23. Controls remained asymptomatic. The inoculated fungus was reisolated from symptomatic leaf tissue. The pathogen was identified as Sclerotinia homoeocarpa (1,2). To our knowledge, this is the first report of Sclerotinia homoeocarpa causing dollar spot disease on Agrostis stolonifera in Argentina and the first report of a disease on golf courses in our country. References: (1) J. E. M. Mordue. Sclerotinia homoeocarpa. No. 618 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1979. (2) R. W. Smiley. Dollar Spot. Pages 14–16 in: Compendium of Turfgrass Diseases. The American Phytopathological Society, St. Paul, MN, 1983.

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Mowing Frequency and Plant Growth Regulator Effects on Dollar Spot Severity and on Duration of Dollar Spot Control by Fungicides

Plant Disease ◽

10.1094/pdis-04-11-0278 ◽

2011 ◽

Vol 95 (11) ◽

pp. 1433-1442 ◽

Cited By ~ 9

Author(s):

Alexander I. Putman ◽

John E. Kaminski

Keyword(s):

Plant Growth ◽

Creeping Bentgrass ◽

Agrostis Stolonifera ◽

Golf Course ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Confounding Effect ◽

Residual Efficacy ◽

The University ◽

University Of Connecticut

Management of dollar spot (incited by Sclerotinia homoeocarpa) on golf course fairways is increasingly challenging. The objectives of this study were to determine the influence of mowing frequency and plant growth regulators (PGRs) on dollar spot severity and on the residual efficacy of fungicides for control of dollar spot. Two 4-month-long studies were conducted on ‘Putter’ creeping bentgrass (Agrostis stolonifera) maintained as a fairway at the University of Connecticut. Treatments were arranged in a three-by-three-by-five factorial that assessed the influence of mowing frequency (2, 4, or 6 days week–1) and PGRs (paclobutrazol, trinexapac-ethyl, or none) on dollar spot control by five fungicide treatments (boscalid, chlorothalonil, iprodione, propiconazole, or none). Turf was mowed in the afternoon hours to minimize the confounding effect of mowing frequency on leaf wetness duration. Treatments were initiated in the late spring of 2007 and 2008, and each fungicide treatment was reapplied only when dollar spot exceeded a threshold of five infection centers plot–1. In the absence of fungicides, dollar spot severity was reduced by 63 to 90% in plots treated with paclobutrazol and by 13 to 55% in plots treated with trinexapac-ethyl. Dollar spot severity was 23 to 50% lower in plots mown 2 days week–1 compared with those mown 6 days week–1. In cases where a significant interaction was observed between mowing frequency and PGRs, dollar spot was reduced on most rating dates in plots treated with trinexapacethyl that were mown 2 days week–1 compared with those mown 6 days week–1. Survival analysis of days until threshold was met revealed that duration of control of fungicides in plots receiving paclobutrazol were 28 to 84% longer compared with plots not receiving PGR. Duration of control by fungicides was generally similar between plots treated with trinexapac-ethyl and no PGR. In general, mowing frequency did not influence duration of control. Results from this study indicate that paclobutrazol could be used to increase the treatment interval of fungicides and that mowing frequency in the absence of dew is likely to have little influence on fungicide residual efficacy. When used without fungicides, PGRs and less frequent mowing may reduce dollar spot in situations where fungicide use is limited.

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First Report of Sclerotinia homoeocarpa from the Sedge Trichophorum cespitosum in Eastern Canada, Which Causes Dollar Spot Disease on Lolium perenne and Poa pratensis but not on Agrostis stolonifera

Plant Disease ◽

10.1094/pdis-07-13-0703-pdn ◽

2014 ◽

Vol 98 (1) ◽

pp. 161-161 ◽

Cited By ~ 1

Author(s):

T. Hsiang ◽

F. Shi ◽

A. Darbyson

Keyword(s):

Lolium Perenne ◽

Poa Pratensis ◽

Agrostis Stolonifera ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Eastern Canada ◽

First Report ◽

Spot Disease ◽

River Region

Sclerotinia homoeocarpa is a fungal pathogen that causes dollar spot disease on more than 40 plant species, mostly in the family Poaceae (1), and is considered the most widespread pathogen of golf course turfgrasses in the St. Lawrence River Region. In June 2011, lesions were observed on tufted bulrush, Trichophorum cespitosum (Poales, Cyperaceae), on the sea shore near Peggys Cove, Nova Scotia, Canada. Single bunches had up to 40% of the leaves affected. The foliar symptoms resembled large hourglass lesions, up to 5 cm long, with a straw colored portion capped at two ends by dark zone lines on surrounding green foliar tissue. Leaf segments were taken, surface sterilized, and placed on potato dextrose agar (PDA). After 3 days of incubation at room temperature, white fluffy mycelia covered the entire petri dish. Brown columnar structures formed in the colony centers after 7 days and cultures became cinnamon colored after 14 days. Dark brown or black substratal stroma were formed on or in the agar, and cultures appeared dark brown from the bottom. DNA was extracted and amplified using primers ITS1 and ITS4 (2), and the amplicon sequenced (GenBank Accession No. KF447776). The sequence showed a top match of 522/524 bp identity with the ITS of an isolate of S. homoeocarpa, with the next 40 top matches also identified as S. homoeocarpa. Two-week-old seedlings of Agrostis stolonifera cv. Penncross, Poa pratensis cv. Touchdown, and Lolium perenne cv. Express were inoculated by placing 5-mm-diameter mycelial plugs from 5-day-old PDA cultures onto the leaves of plants grown in small containers, and incubating under enclosed humid conditions throughout the test. White aerial hyphae on the leaves and straw-colored leaf lesions were observed by 7 days after inoculation on P. pratensis and L. perenne, but no lesions or hyphal growth were observed on A. stolonifera. No signs or symptoms were observed on leaves where sterile agar plugs were used as inoculum. These tests were repeated three times with the same results, and a positive control was included by using an S. homoeocarpa isolate known to be pathogenic to A. stolonifera under the same test conditions. Disease was observed on A. stolonifera with the control isolate. S. homoeocarpa was re-isolated from the lesions on P. pratensis and L. perenne to satisfy Koch's postulates. To the best of our knowledge, this is the first report of S. homoeocarpa on T. cespitosum worldwide, an isolate that was found to cause disease on P. pratensis and L. perenne, but was not pathogenic to A. stolonifera in vitro. The original host was not used in pathogenicity tests because it is considered an endangered species in many locations. References: (1) B. Walsh et al. HortScience 34:13, 1999. (2) T. J. White et al. PCR protocols, a guide to methods and applications 18:315, 1990.

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First Report of Dollar Spot Disease, Caused by Sclerotinia Homoeocarpa, of Agrostis Stolonifera in Sweden

Crop Science ◽

10.2135/cropsci2016.10.0835 ◽

2017 ◽

Vol 57 (S1) ◽

Cited By ~ 2

Author(s):

Tatsiana Espevig ◽

May Bente Brurberg ◽

Marina Usoltseva ◽

Åslög Dahl ◽

Agnar Kvalbein ◽

...

Keyword(s):

Agrostis Stolonifera ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

First Report ◽

Spot Disease

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First Report of Stem-End Rot of Mango Caused by Phomopsis mangiferae in Taiwan

Plant Disease ◽

10.1094/pdis-93-7-0764a ◽

2009 ◽

Vol 93 (7) ◽

pp. 764-764 ◽

Cited By ~ 2

Author(s):

Y. Ko ◽

C. W. Liu ◽

C. Y. Chen ◽

S. Maruthasalam ◽

C. H. Lin

Keyword(s):

Mangifera Indica ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

The United States ◽

Fluorescent Light ◽

Continuous Exposure ◽

Tropical Fruit ◽

First Report ◽

Agar Plug ◽

Rot Disease

Mango (Mangifera indica L.) is grown on approximately 20,000 ha in Taiwan. It is an economically important crop and the income of many fruit farmers comes primarily from mango production. During 2006 and 2007, a stem-end rot disease was observed 1 week after harvest on 28 to 36% of stored mangoes picked from six orchards in the Pingtung, Tainan, and Kaoshiung regions. Two popular mango cultivars, Keitt and Irwin, showed greater susceptibility to this disease, while ‘Haden’ was found to be moderately susceptible. In storage, symptoms initially appeared as light-to-dark brown lesions surrounding peduncles. Rot symptoms advanced slowly but eventually penetrated the mesocarp, which consequently reduced the commercial value of fruits. The fungus formed abundant pycnidia (0.1 to 0.6 mm in diameter) on infected fruits in advanced stages of symptom development. Pieces of symptomatic fruits plated on acidified potato dextrose agar (PDA) and incubated at 25 ± 1°C consistently yielded the same fungus. A single conidial isolate was cultured. Pycnidia developed on PDA after continuous exposure to light for 9 to 14 days. On the basis of morphological characteristics, the fungus was identified as Phomopsis mangiferae L. (2,3). Pycnidia released two types of conidia: α-conidia (5 to 10 × 2.3 to 4.0 μm) were hyaline and oval to fusoid; and β-conidia (15.0 to 37.5 × 1.3 to 2.5 μm) were hyaline and filiform with characteristic curves. Conidiophores were hyaline, filiform, simple or branched, septate, and 15 to 75 μm long. Cultures incubated under continuous fluorescent light (185 ± 35 μE·m–2·s–1) at 25°C for 3 days were used as inoculum for pathogenicity tests. Five fruits from ‘Keitt’ were wounded with a sterilized scalpel and each wound (2 × 2 × 2 mm) was inoculated with either a 5-mm mycelium agar plug or a 0.5-ml spore suspension (105 conidia per ml) of the fungus. Five wounded fruits inoculated with 5-mm PDA plugs or sterile water alone served as controls. Inoculated areas were covered with moist, sterile cotton. Fruits were enclosed in plastic bags and incubated at 24°C for 3 days. The test was performed three times. The same symptoms were observed on all inoculated fruits, whereas no decay was observed on control fruits. Reisolations from the inoculated fruits consistently yielded P. mangiferae, thus fulfilling Koch's postulates. This disease has previously been reported in Australia, Brazil, China, Cuba, India, Malaysia, and the United States (1). To our knowledge, this is the first report of P. mangiferae causing stem-end rot disease on mangoes in Taiwan. Our report necessitates taking preventive strategies in the field, prior to or after harvest, to contain postharvest losses in mangoes. References: (1) G. I. Johnson. Page 39 in: Compendium of Tropical Fruit Diseases. R. C. Ploetz et al., eds. The American Phytopathological Society. St. Paul, MN, 1994. (2) R. C. Ploetz, ed. Page 354 in: Diseases of Tropical Fruit Crops. CABI Publishing. Wallingford, UK, 2003. (3) E. Punithalingam. No. 1168 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1993.

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First Report of Dollar Spot Caused by Sclerotinia homoeocarpa on Agrostis stolonifera in North Dakota

Plant Disease ◽

10.1094/pdis-03-12-0278-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1071-1071

Author(s):

J. M. LeBoldus ◽

Q. Zhang ◽

K. Kinzer

Keyword(s):

New York ◽

North Dakota ◽

Signs And Symptoms ◽

Creeping Bentgrass ◽

Agrostis Stolonifera ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Full Spectrum ◽

Spot Disease ◽

Plastic Bags

Dollar spot disease is a major concern for golf courses nationwide, resulting in poor turf quality and significant damage to playing surfaces. To manage this disease effectively, fungicides need to be applied regularly. This management strategy represents a significant cost to turfgrass managers and may impact the economics of the industry in North Dakota. In the summer of 2011, small, circular, sunken brown patches of dead turf approximately 5 cm in diameter and resembling dollar spot disease were observed on a creeping bentgrass (Agrostis stolonifera L.) variety trial at the North Dakota State University Agricultural Experiment Station in Fargo, ND. Fresh individual leaf specimens with distinct lesions having straw colored centers and reddish brown margins were collected. Leaves were surface disinfected in a 0.05% sodium chloride solution for 60 s, rinsed three times in sterile distilled water, then placed onto potato dextrose agar (PDA). Three isolates were obtained from the disease infested leaves with similar morphology to that described for Sclerotinia homoeocarpa F.T. Bennett (1). Fungal colonies were initially colorless followed by the development of sparse white columnar aerial mycelia with cinnamon colored bases. Hyphae were 5 to 8 μm wide and thin walled with dense granular contents and septations at irregular intervals. Fourteen days after culturing, dark brown to black mycelial stroma developed. A single representative isolate was selected to conduct inoculations. Inoculum was produced by placing six 5-mm-diameter plugs of PDA with actively growing mycelium into an Erlenmeyer flask with 40 g of sterile millet seed. The inoculum was incubated for 14 days at ambient temperature (20 to 25°C). Three creeping bentgrass cultivars, Crenshaw, Declaration, and L-93, were inoculated (two pots per cultivar). Following inoculation, the pots were misted with water, sealed in separate plastic bags, and placed in the dark for 48 h. For the next 5 days, plants were placed for 8 h outside of bags on a bench with full spectrum fluorescent bulbs, followed by 16 h in plastic bags in the dark. Finally, pots were placed on a bench for 48 h. Signs and symptoms of S. homoeocarpa developed on all pots, whereas the controls remained asymptomatic. The same fungus was reisolated from grass leaves, satisfying Koch's postulates. To confirm the identity of the fungus, the internal transcribed spacer was amplified using the ITS4 and ITS5 primers (2). The amplicon was sequenced, generating a 549-bp sequence (Accession No. JQ735942) with 100% similarity to sequences of S. homoeocarpa in GenBank (Accession Nos. GQ924924.1, GQ924923.1, and EU123801.1). To our knowledge, this is the first confirmed report of dollar spot in North Dakota. References: (1) F. T. Bennett. Ann. Appl. Biol. 24:236, 1937. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press Inc., New York, 1990.

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Simulated Rainfall and Mowing Impact Fungicide Performance When Targeting Dollar Spot in Creeping Bentgrass

Plant Disease ◽

10.1094/pdis-94-5-0596 ◽

2010 ◽

Vol 94 (5) ◽

pp. 596-603 ◽

Cited By ~ 8

Author(s):

R. L. Pigati ◽

P. H. Dernoeden ◽

A. P. Grybauskas ◽

B. Momen

Keyword(s):

Field Study ◽

Creeping Bentgrass ◽

Agrostis Stolonifera ◽

Sclerotinia Homoeocarpa ◽

Simulated Rainfall ◽

Dollar Spot ◽

Percent Reduction ◽

Initial Application ◽

Simulated Rain ◽

Disease Pressure

In this 2-year field study, four chemically diverse fungicides (i.e., chlorothalonil, boscalid, iprodione, and propiconazole) were evaluated for their ability to control dollar spot (Sclerotinia homoeocarpa) in creeping bentgrass (Agrostis stolonifera) as affected by simulated rain and mowing timing. Simulated rain (25 to 32 mm) was imposed about 30 min after fungicide application and was compared to rain-free plots. One set of plots was mowed in the morning when the canopy was wet with dew and compared to plots that were mowed when the canopy was dry in the afternoon. The percent reduction in dollar spot control associated with simulated-rain versus rain-free treatments in 2007 and 2008, respectively, was as follows: chlorothalonil 67 and 83%; propiconazole 42 and 79%; boscalid 48 and 70%; and iprodione 33 and 66%. When disease pressure was low, all fungicides subjected to simulated rain provided effective dollar spot control for 7 or more days following the initial application in each year. Across all fungicide-treated plots over 2 years, the average percent reduction in dollar spot associated with morning mowing ranged from 54 to 65%. The reduction in dollar spot severity in morning-mowed plots improved the performance of all fungicides.

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First Report of Dollar Spot, Caused by Sclerotinia homoeocarpa, of Creeping Bentgrass in Norway

Plant Disease ◽

10.1094/pdis-07-14-0775-pdn ◽

2015 ◽

Vol 99 (2) ◽

pp. 287-287 ◽

Cited By ~ 4

Author(s):

T. Espevig ◽

M. B. Brurberg ◽

A. Kvalbein

Keyword(s):

Room Temperature ◽

Aerial Mycelium ◽

Its Region ◽

Creeping Bentgrass ◽

Grass Species ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Running Water ◽

First Report ◽

Plastic Bags

In September 2013, symptoms similar to dollar spot caused by Sclerotinia homoeocarpa F.T. Benn., were observed on creeping bentgrass (Agrostis stolonifera L.) fairways at Losby Golf Course, Lørenskog, Akershus County, in Norway (59.8864′ N, 10.9862′ E). There were small, circular spots and larger irregular patches of sunken, bleached, straw-colored turf. Affected leaves had light-tan lesions with light reddish-brown margins (2). Abundant aerial mycelium was observed in the diseased turf after incubation for 24 h at room temperature in a moist chamber. The mycelium was septate with y-shaped branches. No spores were observed. Diseased leaf segments were washed 30 min in cold running water, surface-sterilized for 60 s using 70% ethanol, placed on water agar, and incubated at room temperature. After 4 days, water agar plugs containing the fungus were transferred to 50% potato dextrose agar (PDA; 19.5 g PDA and 7.5 g agar per 1 liter of media). The fungus colonized the entire 9-cm PDA plates in 6 days. The diameter of the hyphae varied from 2.5 to 12.5 μm. The white, floccose mycelium turned olive green after 7 days and cinnamon brown after 21 days. The cultures became brown from the bottom, forming flat, dark-brown stroma of 0.5 to 5.0 mm in diameter. DNA was extracted from three isolates (from different plants) using a DNeasy Plant Mini Kit (Qiagen). The ribosomal internal transcribed spacer (ITS) region was PCR-amplified using primers ITS1 and ITS4 (3). All three isolates were identical in sequence (GenBank Accession No. KJ775860) and showed up to 97.6% similarity with isolates of S. homoeocarpa of the common type (C-type; e.g., GenBank Accession No. HQ449691) (1). This similarity is considered quite low within a species and indicates that the Norwegian isolates are distinct from other S. homoeocarpa. For Koch's postulates, the fungus was scraped off 21-day-old PDA cultures and chopped, using a sterile scalpel. All three sequenced isolates were pooled and mixed with 200 ml of autoclaved water. Four mature, healthy sod plugs of creeping bentgrass cv. Independence (10-cm-diameter and 10-cm-depth) were taken from an experimental golf green at Landvik, inserted into pots, and inoculated by even distribution of 50 ml of the fungal suspension. Two control pots with creeping bentgrass received 50 ml of sterile water only. All six pots were incubated individually in plastic bags at room temperature and 16-h daylight. After 14 days, 30 to 90% of the inoculated pots of turfgrass exhibited dollar spot symptoms and controls remained healthy. The fungus was recovered from inoculated turf and identified morphologically. This is the first report of dollar spot on any grass species in Norway. For climatic reasons, dollar spot has been considered to be nonexistent in Scandinavia. However, during recent years, symptoms resembling dollar spot have been observed on more than 15 golf courses in Sweden, Denmark, and Norway, and the damage has varied from low to severe. The disease has been given the Norwegian name myntflekk (i.e., coin spot). References: (1) D. Liberti et al. Phytopathology 102:506, 2012. (2) J. D. Smith et al. Fungal diseases of amenity turf grasses. E. & F. E. Spon, London. 1989. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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Effects of Dew Removal and Mowing Frequency on Fungicide Performance for Dollar Spot Control

Plant Disease ◽

10.1094/pdis-12-10-0941 ◽

2011 ◽

Vol 95 (11) ◽

pp. 1427-1432 ◽

Cited By ~ 1

Author(s):

Tanner C. Delvalle ◽

Peter J. Landschoot ◽

John E. Kaminski

Keyword(s):

Severe Disease ◽

Late Summer ◽

Creeping Bentgrass ◽

Weather Conditions ◽

Threshold Level ◽

Agrostis Stolonifera ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Point Of Reference

Dollar spot (Sclerotinia homoeocarpa) is a severe disease problem on creeping bentgrass (Agrostis stolonifera) fairways. The objective of this study was to evaluate the effects of dew removal and mowing frequency on fungicide performance for dollar spot control. In 2009 and 2010, an experiment involving daily dew removal or no dew removal, mowing frequency (2, 4, and 6 days week–1), and fungicides (chlorothalonil, propiconazole, and iprodione) was conducted on creeping bentgrass maintained as a fairway. Daily dew removal resulted in fewer dollar spot infection centers (IC) compared with not removing dew during late summer 2009 and 2010 for all mowing-frequency and fungicide treatments. As mowing frequency increased from 2 to 6 days week–1, dollar spot IC decreased when averaged across all fungicide treatments. For all fungicides, daily dew removal increased the number of days needed to reach a 15-IC plot–1 point of reference when compared with fungicide treatments in which dew was not removed. The number of days required to reach 15 IC varied with fungicide, mowing frequency, and year the test was conducted. Results demonstrate that dollar spot control with fungicides can be extended when daily dew removal is employed and, in some cases, when mowing frequency is increased on dew-covered turf. Benefits of dew-removal practices on dollar spot and fungicide performance can vary with weather conditions, fungicide, threshold level, and possibly other factors.

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First Report of Dollar Spot of Sandbur Caused by Sclerotinia homoeocarpa in Oklahoma

Plant Disease ◽

10.1094/pdis-03-14-0244-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1160-1160

Author(s):

F. Flores ◽

N. R. Walker

Keyword(s):

Warm Season ◽

Its Region ◽

Small Subunit ◽

Type I ◽

Academic Press ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

First Report ◽

Small Subunit Rdna ◽

Disturbed Soils

Sandbur (Cenchrus incertus Curtis) is a warm-season, annual, noxious, grassy weed native to southern North America. It is common in sandy, disturbed soils and can also be found in home lawns and sport fields where low turf density facilitates its establishment. In July 2013, after a period of frequent rainfall and heavy dew, symptoms of dollar spot-like lesions (1) were observed on sandbur plants growing in a mixed stand of turf-type and native warm-season grasses in Logan County, Oklahoma. Lesions, frequently associated with leaf sheaths, were tan and surrounded by a dark margin. Symptomatic leaves were surface sterilized and plated on potato dextrose agar amended with 10 ppm rifampicin, 250 ppm ampicillin, and 5 ppm fenpropathrin. After incubation, a fungus morphologically identical to Sclerotinia homoeocarpa Bennett was consistently isolated. The nuclear ribosomal internal transcribed spacer (ITS) region of two different isolates, SCL2 and SCL3, were amplified using primers ITS4 and ITS5 (2). The DNA products were sequenced and BLAST analyses were used to compare sequences with those in GenBank. The sequence for isolate SLC2 was 869 bp, contained a type I intron in the 18S small subunit rDNA, and was identical to accession EU123803. The ITS sequence for isolate SLC3 was 535 bp and identical to accession EU123802. Twenty-five-day-old seedlings of C. incertus were inoculated by placing 5-mm-diameter agar plugs, colonized by mycelia of each S. homoeocarpa isolate, onto two of the plants' leaves. Plugs were held in place with Parafilm. Two plants were inoculated with each isolate and sterile agar plugs were placed on two leaves of another seedling as control. Plants were incubated in a dew chamber at 20°C and a 12-h photoperiod. After 3 days of incubation, water-soaked lesions surrounded by a dark margin appeared on inoculated plants only. Fungi that were later identified as S. homoeocarpa isolates SLC2 and SLC3 by sequencing of the ITS region were re-isolated from symptomatic leaves, fulfilling Koch's postulates. To our knowledge, this is the first report of dollar spot on sandbur. References: (1) R. W. Smiley et al. Page 22 in: Compendium of Turfgrass Diseases. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2005. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

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