Identification and risk assessment for dollar spot on Scandinavian golf courses

Summary

Dollar spot is a common disease (caused by the fungus Sclerotinia homoeocarpa) on amenity turf in Australasia, North and Central America and continental Europe. During recent years, the disease has been identified on many golf courses in Scandinavia since it was first officially documented in Norway in summer 2013 (Espevig et al., 2015) and in Sweden in 2014 (Espevig et al., in press). Thus, there is need for risk assessment of dollar spot. From July to October 2014, around 30 samples of turf with dollar spot symptoms were collected in Sweden, Denmark and Norway, and presence of S. homoeocarpa was confirmed on seven Swedish, four Danish and one Norwegian golf course. Molecular analysis of the isolates showed that they could be divided into two genetic groups (with 97.6% similarity between the groups).

Group 1 consisted of all Danish and most of the Swedish isolates, while Group 2 contained the Norwegian isolate and two Swedish isolates. The consensus internal transcribed regions (ITS) of the ribosomal DNA of the first group was identical to ITS previously reported in e.g. the USA (GenBank), while the second group clearly constituted a distinct variant or perhaps even a new species of Sclerotinia. In December 2014, we also received four isolates from cool-season grasses and two isolates from warm-season grasses from the Systematic Mycology & Microbiology Lab, US Department of Agriculture, for comparison. These isolates represent a wide swathe of diversity for S. homoeocarpa and they were sequenced by NIBIO Plant Health and Plant Protection in 2015. All four isolates from cool-season turfgrasses belonged to Group 1, while two isolates from warm-season turfgrasses belonged to two other groups (3 and 4). In compliance with the project description, the second project year (2015) was largely devoted to knowledge transfer and publication of the results. Thus, a fact-sheet about dollar spot (myntflekk in Norwegian) was published in English, Swedish and Norwegian on the STERF website, and BSc student Anita Ejderdun
at the University of Gävle defended her dissertation on dollar spot disease. She received four isolates of S. homoeocarpa from NIBIO (one from Sweden, two from Denmark and one from Norway) and tested their pathogenicity at 6 °C, 15 °C and 24 °C on creeping bentgrass (Agrostis stolonifera) from two golf courses. Her findings indicated that the optimal temperature for disease development varied between the isolates and that the pathogen had potential for growing under relatively cold climate conditions.

Fundings (kSEK)

Project objectives

• To identify and monitor dollar spot on 2-3 golf courses in Norway, Denmark and Sweden and provide scientific documentation in the form of a BSc dissertation on dollar spot distribution on Scandinavian golf courses with respect to geography, climate conditions, type of turf, turfgrass species, maintenance practices etc.
• To compare Scandinavian and American Sclerotinia homoeocarpa isolates.
  
• Based on results from this project, the IPM principles, BSc dissertation and literature studies, to develop a STERF fact sheet on dollar spot risk assessment.

 

Project participants

Tatsiana Espevig

Researcher

Norwegian Institute for Bioeconomy (NIBIO), Department for Urban Greening and Environmental Technology, Turfgrass Research Group, Landvik, Reddalsveien 215, 4886 Grimstad, Norway.

+47 406 23 778

Send e-mail