Activities during July consisted of intensive field examination of in- 

 fected trees, and laboratory isolation, pure culture, and attempted identifica- 

 tion of the associated fungi. These activities were conducted in fulfillment 

 of purposes 1 and 2. During August and early September the field procedure 

 developed was employed in preliminary extensive tree examinations in two drain- 

 ages, in fulfillment of purpose 3. Beginning in late June and continuing into 

 early September, similar examinations were made of bettle-attacked trees, in 

 fulfillment of purpose 4. 



INTENSIVE TREE EXAMINATION 



A preliminary field examination of the roots of infected trees was 

 deemed desirable as a background for methods and techniques to be used in this 

 study. Four areas were studied which appeared to be centers of root diseases. 

 These were in 10-20, 41-60, 61-80, and 161-200 year age classes. Roots of 

 27 trees were examined by baring the roots, peeling their bark, and recording 

 detailed observations, a tree bared for examination is shown in plate 1-B. 



The results of the examination showed that: an examination confined to 

 the root surfaces adjacent to the root collar would not disclose the presence 

 of all infection since infection apparently may start at any point on the 

 root surface; the appearance of the crown may be a good indicator of the 

 seriousness of infection; the rapidity of fungal activity varies greatly; 

 rhizormorphs are abundant in the soil of the white pine type; measurements of 

 the annual rings above infected and uninfected lateral roots yield worth- 

 while information on the duration of serious infection. 



CULTURE OF ASSOCIATED FUNGI 



Since it was found difficult at the start to distinguish between the 

 diseases on the basis of their symptomatology, it was decided to attempt the 

 isolation of the associated fungi from the roots of a number of the inten- 

 sively examined trees. Approximately half of the attempted sets of isolations 

 from mycelial fans and infected sapwood were successful and of 52 separate 

 isolates, 31 represented Armillaria mellea , 10 Fomes annosus , and 11 unidenti- 

 fied fungi. None of the attempted isolations from rhizomorphs proved suc- 

 cessful. Fruiting bodies of A. mellea are shown in plate 1-A. 



EXTENSIVE TREE EXAMINATION 



The exploratory work in field and laboratory had shown that a relatively 

 rapid tree-examination procedure could be expected to disclose advanced in- 

 fection in the root collar and, in most cases, permit its diagnosis. Since 

 information was lacking on the rate of spread of infection in the individual 

 tree and the possible influence of site and tree vigor upon this rate, precise 

 data on incidence of infection could have but little meaning. Information on 

 the incidence of infection so advanced that it could be presumed to be retard- 

 ing increment appreciably and dooming the tree to early death was deemed of 

 significance, however. Because a relatively rapid tree-examination procedure 



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