THE AUTHORS 



GERAL I. McDonald is principal pathologist with the 

 Intermountain Research Station's Genetics and Pest 

 Resistance Research Work Unit in Moscow, ID. He re- 

 ceived a B.S. degree in forest management (1963) and 

 Ph.D degree in plant pathology (1969) from Washington 

 State University. Since joining the Station in 1966, he has 

 studied the epidemiology and genetic interaction of the 

 blister rust organism and its hosts. He is now studying the 

 ecological genetics of conlfer-Armillaria interactions. 



NEIL E. MARTIN is research plant pathologist with the 

 Intermountain Research Station's Silviculture and Pathol- 

 ogy Research Work Unit in Moscow, ID. He received a 

 B.S. degree in botany (1961) from Iowa State University, 

 an M.S. degree in plant pathology (1964) from South 

 Dakota State University, and a Ph.D. degree in plant 

 pathology (1972) from Washington State University. Since 

 joining the Station in 1966, he has studied blister rust, 

 dwarf mistletoe, and root rot. 



ALAN E. HARVEY is principal plant pathologist with the 

 Intermountain Station's Forestry Sciences Laboratory in 

 Moscow, ID. He received a B.S. degree in biology (1960), 

 an M.S. degree in plant pathology (1962), and a Ph.D. 

 degree in plant pathology (1968). He completed one 

 academic year of postgraduate work in plant pathology 

 in 1972. 



RESEARCH SUMMARY 



The distribution of Armillaria spp. on National Forests of 

 the Northern Rocky Mountains was investigated through 

 random installation and inspection of 0.04-ha plots. Woody 

 plant species living and dead were searched for fans, rot, 

 or rhizomorphs typical of Armillaria spp., which were then 

 verified through laboratory cultures. Armillaria occurrence 

 was found to be related to a root rot risk-rating system 

 based on the current system for classifying vegetational 

 communities. Armillaria spp. were absent from the warm 

 and dry juniper and pinegrass habitat types (h.t.'s) of the 

 Douglas-fir series, the cold and dry beargrass and grouse 

 whortleberry h.t.'s of the subalpine fir series, the cold and 

 wet twisted stalk h.t.'s of the subalpine fir series, and the 

 frost-pocket dwarf huckleberry h.t.'s of both the Douglas-fir 

 and subalpine fir series. 



Data linking Armillaria spp. to host and ecological 

 function (epiphyte, saprophyte, or pathogen) were also 

 recorded. These data will be reported in future papers 

 after more reliable methods have been developed for 

 assigning isolates to their correct taxonomic positions. We 

 expect to find that certain Armillaria spp. are pathogenic 

 on conifers in general or maybe even on specific conifer 

 species, and that their geographic distribution is related to 

 habitat type. 



August 1987 



Intermountain Research Station 

 324 25th Street 

 Ogden, UT 84401 



