sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDU Faculty of Forestry Journal
Serial: A, Number: Special Issue, Year: 2009, ISSN: 1302-7085, Page: 264
RESPONSE OF Alnus tenuifolia TO INOCULATION WITH Valsa
melanodiscus
Glen R. STANOSZ 1* , L. M. TRUMMER 2 , J. K. ROHRS-RICHEY 3 , G. C.
ADAMS 4 , J. T. WORRALL 5
1 Department of Plant Pathology, University of Wisconsin-Madison, WI, 53706, USA
2 USDA Forest Service, Forest Health Protection, Anchorage, AK, 99503, USA
3 Department of Biology and Institute of Arctic Biology, University of Alaska Fairbanks, AK, 99775,
USA
4 Department of Plant Pathology, Michigan State University, East Lansing, MI, 48824, USA
5 USDA Forest Service, Forest Health Management, Gunnison, CO, 81230, USA
* grs@plantpath.wisc.edu
Valsa melanodiscus (anamorph Cytospora umbrina) is associated with cankered
and killed alder (Alnus) stems in western North America from Colorado to Alaska.
The responses of thinleaf alder (A. tenuifolia) stems to inoculation with each of two
isolates of V. melanodiscus were studied in south-central Alaska. At each of two
sites, eight stems per isolate were wounded to expose both inner bark and sapwood
and inoculated in early May 2007 by placing a colonized agar plug over the wound.
Sterile agar plugs were applied to wounded control stems. Sunken, elongated
cankers similar to those with which V. melanodiscus has been associated resulted
on inoculated stems. In contrast, wounded control stems exhibited strong callus
production and wound closure. In September 2007, cankers were harvested and
lengths were recorded. Mean canker lengths measured externally (data for both
isolates pooled) at the two sites were 45 (range 20-156) mm and 73 (range 22-201)
mm. Analysis of variance of log transformed data revealed strong support for effect
of location (P = 0.04), but not that of isolate (P = 0.12) or interaction (P = 0.20) on
canker length. The fungus was reisolated from each inoculated stem, but not from
any control stem. The ability of V. melanodiscus to cause cankers on thinleaf alder
stems is confirmed, and these results support the conclusion that this pathogen is a
cause of alder dieback in western North America.
264