390 R - M. RAUTER AND L. ZUFA 



The described technique will determine whether blister rust mycelium 

 is present in trees which often lack Cronartium ribieola symptoms. It 

 will establish the presence or absence of blister rust in a latent stage 

 in spme healthy looking but slow growing, blister rust-inoculated plants. 

 This technique will also be of value for an early confirmation of a 

 blister rust attack, as we were able to identify the blister rust mycelium 

 in the bark tissue of seedlings 5 months after inoculation. 



SUMMARY 



A double stain consisting of safranin and fast green applied as a 

 single solution gives differentially stained and cleared slides in 10 

 minutes, showing the wide green hyphae and red nuclei of blister rust 

 when present. 



LITERATURE CITED 



Boyer, M. G. 1964. Studies on white pine phenols in relation to blister 



rust. Can. J. Bot. 42: 979-987. 

 Boyer, M. G. 1967. The relation of growth regulators to the development 



of symptoms and the expression of stem resistance in white pine 



infected with blister rust. Can. J. Bot. 45: 501-513. 

 Gram, K. and E. Jorgensen. 1953. An easy, rapid and efficient method of 



counter-staining plant tissues and hyphae in wood-sections by means of 



fast green or light green and safranin. FRIESIA IV, 4-5: 262-266. 

 Hirt, R. R. 1964. Cronartium ribieola, its growth and reproduction in 



the tissues of eastern white pine. State Univ. Coll. Forest. Tech. 



Publ. 86, Syracuse. 30 p. 

 Jewell, F. F. 1958. Stain technique for rapid diagnosis of rust in 



southern pines. Forest Sci. 4(1): 42-44. 

 Waterman, A. M. 1955. A stain technique for diagnosing blister rust in 



cankers on white pine. Forest Sci. 1(3): 219-221. 



FLOOR DISCUSSION 



SCHUTT: Can you distinguish blister rust mycelium from mycelium 

 of other organisms, and did you compare blister rust mycelium with 

 mycelium of other organisms? 



ZUFA: We did not make any comparison of this kind. 



JEWELL: The hastorium shown on the slide identified the fungus as 

 a basidiomveete. Therefore, it's likely that it was blister rust. 



