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| Web URL(s): | http://archive.lib.msu.edu/tic/rpr/1999/72304,%20Cornell,%20Harman.PDF
Last checked: 02/25/2013
Requires: PDF Reader |
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| Publication Type:
| Report |
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| Material Type: | Manuscript |
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| Monographic Author(s): | Harman, Gary E.; Ondik, Kristen L.; Nelson, Eric B. |
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| Author Affiliation: | Garman and Ondik: Department of Horticultural Sciences, Cornell University, NYSAES, Geneva, NY; and Nelson: Department of Plant Pathology, Cornell University, Ithaca, NY |
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| Monograph Title: | The Basic Biology and Etiology of Sclerotinia Homoeocarpa, The Casual Agent of the Dollar Spot: 1999 USGA Annual Report, 1999. |
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| Publishing Information: | Geneva, New York: Cornell University NYSAES; Ithaca, New York: Cornell University |
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| # of Pages: | 8 |
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| Collation: | [1], 6, [1] pp. |
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| Abstract/Contents: | "This research was designed to investigate the following objectives: 1. To examine the development, including possible apothetical production, of the pathogen in creeping bentgrass greens when present in leaf tissue, in root tissue, or as isolated stroma and to determine the length of survival of the pathogen in infected tissue or as stroma. 2. To measure the genotypic variation of the pathogen from similar and diverse geographical locations using RAPD analysis and anastomosis groupings. Mesh bags containing an isolate of the fungus were buried in a bentgrass green and then retrieved at various times throughout the year. Upon examination we found that the fungus exhibited two distinct growth phases. One phase grows rapidly and is characterized by copious amounts of hyphae. The other phase is slow growing with smaller colonies for about seven days and then a sudden burst of rapid growth typical of the first phase. We hypothesize that S. homoeocarpa is present most of the time on turf in a dormant, nonpathogenic state. When directed by environmental or other cues, the fungus suddenly grows rapidly and becomes pathogenic, causing an explosive epiphytotic. In order to examine the natural infection of dollar spot, colored tees were used to mark certain dollar spots from which turf samples can be taken repeatedly over time. Nonsymptomatic areas were also marked. As expected, samples taken in August (when dollar spot was infective) showed actively growing phase but not the dormant phase. In November we expect to see the dormant phase of the fungus since the infection phase is finished. Sampling will then resume in the spring, when we once again expect to see the dormant phase, and will continue into late summer when dollar spot epiphytotics usually occur in upstate New York. Epiphytotics of dollar spot can occur at various times in different areas of the United States and pathogenicity levels can vary depending on turfgrass cultivar. Understanding the genetic diversity of S. homoeocarpa is important for controlling and managing the disease. Thus, we collected over 50 isolates of the dollar spot fungus from around the US and Canada to determine their genetic relatedness using RAPDs and anastomosis groupings. Our results are as follows: Great diversity exists among collected isolates of S. homoeocarpa.; Only a few isolates share the same overall banding pattern, mostly those from the same location and the same cultivar of turfgrass.; The isolate sh105ko demonstrates an unusual growth pattern during anastomosis pairings: it coils around the hyphae of the other isolate similar to coiling characteristic of biocontrol interactions. Upcoming Research: 1. Mitochondrial DNA (mDNA) assays will be performed to provide a more complete genetic survey of the isolates. Cladistic analyses will be completed to obtain groups with most similar and most dissimilar genotypes. 2. We will determine whether dissimilar types have similar or different modes of infection and levels of pathogenicity to bentgrass. 3. We will continue to isolate and observe the pathogen from bags in soil and from naturally-infected turf." |
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| Language: | English |
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| References: | 0 |
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| See Also: | See also related summary article, "The basic biology and etiology of Sclerotinia homoeocarpa, the casual agent of dollar spot", 1999 Turfgrass and Environmental Research Summary [USGA], 1999, p. 24, R=72304. R=72304 |
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| Note: | Pictures, b/w
Tables
"USGA Annual Report, November 1999" |
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| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
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