Editorial Type:
Article Category: Research Article
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Online Publication Date: 01 Dec 2010

Susceptibility of Viburnum Species and Cultivars to Phytophthora ramorum

Page Range: 197 – 202
DOI: 10.24266/0738-2898-28.4.197
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Abstract

Phytophthora ramorum causes ramorum blight on Viburnum species, which are commonly grown as ornamentals. This study evaluated 24 different species or cultivars for susceptibility to P. ramorum. Whole plants were inoculated with an NA1 isolate of P. ramorum and placed in dew chambers at 20C (68F). After 5 days, the percentage of necrotic leaves for each plant and the percentage of necrotic area for each leaf were calculated. The percentage of necrotic leaves per plant ranged from 96.1% (V. tinus) to 7.9% (V. opulus ‘Notcutt’) and the percentage of necrotic leaf area ranged from 73.0% (V. × carlcephalum ‘Cayuga’) to 2.4% (V. trilobum ‘Wentworth’). In addition, six species or cultivars were evaluated for their susceptibility to a EU1 isolate of P. ramorum. The isolate had a significant effect on three of the six species or cultivars tested, although one isolate did not always yield the greatest necrosis. Evergreen species and cultivars had a higher percentage of necrotic leaves and higher percentage of necrotic leaf area than semi-evergreen or deciduous species and cultivars. All Viburnum species and cultivars showed some degree of susceptibility to P ramorum.

Keywords: host range; ornamental; ramorum blight; sudden oak death; Allegany lantanaphyllum viburnum (V. × rhytidophylloides ‘Allegany’); arrowwood viburnum (V. dentatum), blue muffin arrowwood viburnum (V. dentatum ‘Blue Muffin’); Burkwood viburnum (V. × burkwoodii), Cayuga hybrid viburnum (Viburnum × carlcephalum ‘Cayuga’); Chesapeake service viburnum (V. utile ‘Chesapeake’); Conoy Burkwood viburnum (V. × burkwoodii ‘Conoy’); Cree leatherleaf viburnum (V. rhytidophyllum ‘Cree’); Cunningham's white rhododendron (Rhododendron ‘Cunningham's White’); dwarf Koreanspice viburnum (V. carlesii ‘Compactum’); Erie linden viburnum (V. dilatatum ‘Erie’); European snowball viburnum (V. opulus ‘Roseum’); fragrant snowball viburnum (V × carlcephalum); Judd viburnum (V. × juddi); laurustinus viburnum (V. tinus); linden viburnum (V. dilatatum); Maries doublefile viburnum (V. plicatum var. tomentosum ‘Mariesii’); Mohawk Burkwood viburnum (V. × burkwoodii ‘Mohawk’); Notcutt European cranberrybush viburnum (V. opulus ‘Notcutt’); Prague viburnum (V. × pragense); Sarco×ii hybrid viburnum (V. × burkwoodii ‘Sarcoxii’); Shasta doublefile viburnum (V. plicatum var. tomentosum ‘Shasta’); summer snowflake doublefile viburnum (V. plicatum var. tomentosum ‘Summer Snowflake’); Wentworth American cranberry viburnum (V. trilobum ‘Wentworth’); willowwood lantanaphyllum viburnum (V. × rhytidophylloides ‘Willowwood’)
Copyright: Copyright, All Rights Reserved 2010

Contributor Notes

The author wishes to thank Steven Dodge for all of his help in the collection of the data and John Phillips, Dana Berner, and Nina Shishkoff for their helpful discussions on statistical analyses of the data. I would also like to thank Nina Shishkoff for her review of the draft manuscript and helpful suggestions. In addition, I would especially like to thank Jim Kohl of Angelica's Nursery and Margaret Pooler of the National Arboretum, for providing plant material. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U.S. Dept. of Agriculture and does not imply its approval to the exclusion of other products or vendors that also may be suitable.

2Research Plant Pathologist. tim.widmer@ars.usda.gov.

Received: 30 Mar 2010
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