A RAPID TECHNIQUE FOR THE DETERMINATION OF CRONARTIUM 

 RIBICJLA MYCELIUM IN WHITE PINE BARK TISSUE 



R. M. Rauter and L. Zufa 

 Research Branch, Ontario Department of Lands & Forests, 

 Maple 3 Ontario 3 Canada 



.ABSTRACT 



Freshly-collected longitudinal bark sections obtained with a 

 scalpel from living tissue adjacent to suspect Cronartiun 

 ribicola cankers were killed in. 50% ethyl alcohol, stained using 

 a modified safranin- fast green schedule, washed in absolute ethyl 

 alcohol, and mounted in "Euparol" or "Permount." Rust mycelium 

 was detected readily from its bright red-stained nuclei and 

 because of its characteristically wide*, green-stained, inter- 

 cellular hyphae. 



INTRODUCTION 



Many bark abnormalities, such as shallow and deep lesions, partial 

 girdling and girdling necroses, wound periderm formations, etc., often 

 resemble Cronartivm ribicola J.C. Fisch. ex Rabenh. symptoms. A technique 

 developed for a rapid and positive confirmation of blister rust mycelium 

 in white pine bark tissue would be of value in such cases. 



REVIEW OF LITERATURE 



Most microscopic analysis and identification of white pine blister 

 rust has involved embedding or freezing the stem of the host tree and 

 sectioning the material on a microtome (Boyer, 1964, 1967; Waterman, 1955). 



Boyer (1967) fixed and embedded his material, then stained with 

 safranin-fast green. Ordinarily this double stain is used in an alcohol 

 series and requires several hours to complete. Waterman's (1955) procedure 

 was shorter. She did not use a fixative and, after boiling the wood block, 

 mounted it on a microtome to obtain sections. Her staining was combined 

 into one step and could be accomplished in 1 hour. Jewell (1958) prepared 

 a rapid stain for rusts using orseillin (or safranin) and aniline blue. 

 He reduced the staining times, but he maintained a multi-stepped staining 

 schedule. The Gram-Jorgensen (1953) staining procedure, used to identify 

 fungi in xylem tissue, requires little time. It takes only a matter of 

 minutes for the stain to take effect. 



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