DANGEROUS INTERNATIONAL FOREST TREE DISEASES 89 



Canker Stain of Plane Trees 



Curtis May 



Agricultural Research Service, U.S. Department of Agriculture, 



Beltsville, Maryland 



Ceratocystis fimbriata Ell. & Halst. (Endoconidiophora fimbriata 

 (Ell. & Halst.) Davidson f. platani Walter) . A lethal bark canker and 

 wood-stain of plane trees in the United States. London plane (Plat- 

 anus aceri folia Willd.), extensively planted as a street tree in the 

 United States, is killed by the disease and Platanus occidentals L. is 

 damaged but rarely killed. Cankers on young, yellow or green bark 

 are at first slightly sunken, lens-shaped, or elongated areas in line with 

 the grain of the underlying wood. Older cankers are sunken, elongate, 

 irregular in outline, becoming rough and blackened. Infected bark 

 dries, cracks, and falls. Wood is discolored reddish brown or bluish 

 black, especially the medullary rays. In cross section, discolored areas 

 of wood often are wedge-shaped. Cankers eventually coalesce. Limbs 

 and trunk are girdled ; members distal to the cankers die. 



The first leaf symptoms to appear are usually dwarfing and yellow- 

 ing. Leaves eventually wilt and fall in summer. On small branches 

 or small stems the disease may cause wilting and defoliation of normal- 

 size green leaves. By the time leaf symptoms become evident, canker 

 development and invasion of wood are extensive. 



Canner stain it, the most serious disease of Platanus acerifolia in 

 the United States. Although canker stain is most destructive on the 

 introduced London plane, the disease has been observed on the native 

 P. Occident alls in wild areas far from cultivated London plane trees. 

 The causal fungus is readily transmitted on prunning tools of all kinds. 

 The fungus invades through wounds. Natural spread occurs but does 

 not appear to be important in comparison with spread through use of 

 contaminated pruning tools and contaminated, non-antiseptic tree 

 wound paintis. In limited tests, isolates of the fungus from London 

 plane were not pathogenic to sweet potato or to cacao seedlings. 



Conidia and perithelia containing ascospores are produced on 

 cankers. Thickrwalled, brown spores form in invaded wood. All 

 spore types can m feet. 



The fungus is indistinguishable morphologically from Ceratocystis 

 ■fimbriata. Ascospores 4.5-8 X 2.5-5/x. Endoconidia 11-16 X 4.5//.. 



Range : Eastern United States 

 Hosts: Platanaceae — 



Platanus acerifolia Willd. 

 P. occidentalis L. 

 P. orientalis L. 

 Literature : 

 Hunt, J. Taxonomy of the genus Ceratocystis. Lloydia 19 : 1-59. 



March 1956. 

 Walter, J. M. Canker stain of plane trees. U.S. Dept. Agr. 

 Yearbook 1943-47 : 481-^84. 1947. 



Canker stain of plane trees. U.S. Dept. Agr. Cir. 742. Jan. 



1946. P " 



Rex, E. G., and Schrieber, R. The rate of progress and de- 



structiveness of canker stain of plane trees. Phytopathology 

 42:236-239. 1952. 



