Table 5— Percentage of disagreement between two readers and 

 agreement to disagree with expectation when Armillaria 

 isolates from clones from different plots within a 

 National Forest are challenged 



National Number of 



Forest challenges No Yes Yes and no 



Percent 



ooeur a Aiene 



\ DO 



yo 







d. 



c. 



Colville 



256 



100 











Clearwater 



76 



98 



1 



1 



Flathead 



264 



93 



3 



4 



Kaniksu 



154 



93 



6 



1 



Kootenai 



232 



89 



8 



3 



Lolo 



240 



94 



6 







Nez Perce 



262 



92 



2 



6 



Payette 



395 



95 



2 



3 



St. Joe 



554 



96 



1 



3 



Umatilla 



568 



96 



1 



3 



Wallowa-Whitman 



129 



93 



7 







Total 



3,283 



95 



2 



3 



on conifers that were showing symptoms from the Armil- 

 laria infection. A sixth class contained clones connected, 

 as above, to conifer pathogenicity but were also found in 

 epiphytic associations with hardwoods. 



There are several trends associated with clone habit. 

 The highest percentage of clones was found on healthy 

 hardwoods and on healthy conifers and/or conifer detritus. 

 These tended to be represented as single isolates (table 6). 

 Clones sampled as multiple isolates tended to be on a 

 variety of host types (shrubs and conifers in table 6). Like- 

 wise, pathogenic clones that occurred on both shrubs and 

 conifers tended to exist on a variety of substrates, but 

 those present only as conifer pathogens tended to occur as 

 single isolates. 



DISCUSSION 

 Clone Definitions 



The vegetative samples used in this study of Armillaria 

 spp., as they exist in the Northern Rocky Mountains, 

 separated into 177 separate and distinct clones. We have 

 yet to directly determine their taxonomic affiliations and 

 some other important traits. As a research resource they 

 provide a sizable population of cultures with demonstrated 

 genetic interrelationships that will provide a population on 

 which to build a classification system based on traits as 

 expressed in culture. This should be done on a large 

 population before species relationships are known. As 

 such, it would allow fair and unbiased determination of the 

 stability of the traits. After a classification based on stable 

 traits is developed, it can be verified by determination of 

 the species of each clone. 



Vegetative collections of Armillaria spp. are believed to 

 be diploid, but the occurrence of haploids has not been 

 studied. These clones will provide an ideal resource on 

 which to study this possibility— for example, haploids can 

 be distinguished by their fluffy aerial mycelium (Anderson 

 and Ullrich 1979; Korhonen 1978), haploid nuclei can be 

 separated from diploid nuclei by microspectrophotometric 

 techniques and nuclear volume measurements (Motta 1985; 

 Peabody and Peabody 1984), and finally, a vegetative 

 isolate that is haptoid would behave differently than a 

 diploid in challenge and mating tests. 



The Challenge System 



Results reported in this paper demonstrate that the 

 reading of isolate compatibility is not without ambiguity; 

 however, our level of error is consistent with that 

 reported by others. Within our population of isolates it ap- 

 pears that about 5 percent of the interpretations between 

 closely related genotypes (tables 1 and 2) are subject to 

 error. This level is less than the 10 percent error level 

 reported for similar interactions within closely related 

 genotypes of A. luteobubalina (Kile 1983). Matings be- 

 tween supposedly compatible haploids also yield 5 to 10 

 percent ambiguous interpretations (Kile 1983; Korhonen 

 1978). Placing numerous unrelated cultures in the same 

 confined space apparently did not lead to unstable 

 challenge results. The system of challenges for field 

 diploid isolates, as used in this study, will give repeatable 



Table 6— Characteristics of Armillaria clones obtained from 

 Northern Rocky Mountain National Forests 





Number 



Percent 







of 



of 



Isolates 



Clone source 



clones 



clones 



per clone 



Hardwood shrubs 



42 



24 



1.2 



Healthy and detritus conifer 



64 



36 



1.4 



Shrubs and conifers 



32 



18 



4.1 



Free soil rhizomorph 



4 



2 



1.0 



Pathogenic on conifers 



22 



12 



1.4 



Shrubs and pathogenic on 









conifers 



13 



7 



4.3 



Total clones 



177 







Number of Clones per Plot 



The average number of clones per plot was 2.3. The 

 average number of isolates per plot was 5.4. Plot SJ-1 

 (table 16, appendix) provided 12 isolates and three clones. 

 A nearby plot, SJ-4 about 17 km northwest, gave the 

 largest number of clones, which was six among eight 

 isolates. 



Clone Habits 



The clones were classified according to their host affilia- 

 tions (table 6). Six mutually exclusive classes were estab- 

 lished. The first included clones existing as rhizomorphs 

 epiphytic on apparently healthy hardwood brush. The 

 second was epiphytic on healthy conifers, as well as 

 conifer detritus. The third class included epiphytic rhizo- 

 morphs on both conifers and hardwoods. The fourth was 

 composed of clones from rhizomorphs unattached to any 

 organic material in the soil. The fifth included clones that 

 were restricted to conifers and connected to conifer patho- 

 genicity by having both fan isolates and epiphytic growth 



7 



