Dasyscyphae on Conifers in North America. III. Dasyscypha Pini

SUMMARY

Investigation of a large-spored, brown-excipled Dasyscypha species, associated with a destructive canker of native Pinus Strobus, P. monticola and P. albicaulis in North America and on P. sylvestris in northern Scandinavia, has shown the pathogen to be distinct from the innocuous saprophyte, D. fuscosanguinea Rehm (1881), with which it hitherto has been regarded as synonymous.

The highland parasite is referred to Brunchorst's species Lachnella Pini (1892) with the new combination,Dasyscypha Pini (Brunchorst) Hahn & Ayers. Morphological and physiological data are presented to support the separation of Brunchorst's parasite from Rehm's Alpine saprophyte of central Europe. Culture characters of D. Pini are given.

D. Pini appears to have a circumpolar distribution, and is to be found only at north latitudes and usually at high elevations (3000′-6000′) on cold mountain slopes or in Arctic pine barrens where climatologie conditions are exceedingly severe. A phytogeographical discussion is given.

Since Brunchorst gave the first description of the disease, very little further study has been made of it in Norway. Lagerberg in Sweden contributed valuable pathological and mycological data with respect to the fungus. In North American the fungus was reported for the first time in 1926. Although it is now known to have been present in the United States for many years, generally distributed over the western white pine region of the Inland Empire at high elevations, the first collection of the fungus was not made until 1922. The disease has been confused with white pine blister rust in the Pacific Northwest; in the Upper Peninsula, Michigan, where it has recently been found, it presents a similar problem. A culture study has shown that North American forms isolated from the three native hosts show satisfactory agreement with isolations from Swedish material collected on Scotch pine at Tärendö in the Arctic region.

The canker caused by D. Pini is very similar to that caused by D. Willkommii (Hartig) Rehm on larch species. The fruiting cups of the former are always to be found, as in the case of the latter, in immediate association with resinous lesions in which the pathogen continues to fruit even after the branch is killed. The organism does not spread saprophytically out into the killed branch beyond. In Scandinavia, Lachnellula chrysophthalma (Pers.) Karst, may colonize such dead parts, in this respect resembling the saprophyte D. calycina Fuckel, which colonizes branches killed or weakened by the European larch canker parasite.

Grateful acknowledgment is due the Director, Dr. Gunnar Samuelsson, and Dr. Th. Arwidsson of Riksmuseets Botaniska Avdelning, Stockholm for affording the authors the opportunity of examining first-hand Rehm's personal herbarium specimens of Dasyscypha for this study; to Prof. Dr. Torsten Lagerberg for herbarium and fresh specimens of Dasyscypha (Lachnella) Pini; to Mr. Ivar Jørstad, Statsmycolog, Oslo, for information on the fungus in Norway. In the United States the authors are also indebted to Dr. J. S. Boyce, Osborn Botanical Laboratory, Yale University, for the privilege of access to his field notes and his herbarium which contains specimens of the fungus examined critically by Prof. J. Dearness, London, Ontario, Canada; to Mr. J. R. Harisbrough and other members of the Division of Forest Pathology, Bureau of Plant Industry who have collected and submitted specimens for this study; to Mr. L. W. Hodgkins and Mr. K. K. Kroeber and other members of the Division of Blister Rust Control, who likewise sent specimens for study; and to Drs. F. J. Seaver, W. W. Diehl, J. H. Faull, D. V. Baxter, H. H. Hubert and Mr. C. R. Stillinger, who have rendered valuable assistance in collecting data for the manuscript.