REV. M. J. BERKELEY ON VARIOUS FORMS OF CANKER. 23 



V. On Various Forms of Canker. 

 By the Eev. M. J. Berkeley, M.A., F.B.H.S. 



It is scarcely possible to give much attention to the subject of 

 Vegetable Pathology without recognizing the fact that diseases 

 apparently very closely connected with each other may be due 

 to entirely dhTerent causes. This is especially true of the vari- 

 ous affections which pass under the name of Canker, than which 

 few are more injurious to the cultivator, and which are so fre- 

 quent in some localities as to make the cultivation of particular 

 varieties a labour, if not entirely hopeless, at least full of vexa- 

 tion and comparative disappointment. 



Many forms of this formidable disease were indicated in the 

 series of articles which appeared some years since in the ' Gar- 

 deners' Chronicle,' on Vegetable Pathology, but which, from 

 various causes, though many applications have been made with a 

 view to their publication in a separate volume, have never passed 

 beyond the pages of that journal. The subject of Canker is, 

 however, of such importance to the cultivator, that, with the 

 sanction of the highest authority in this country on pomology, 

 I have been induced to reconsider the various forms which it as- 

 sumes, and to publish the results in this Journal. 



Every one on hearing . the name will call to mind the ravages 

 which he has witnessed amongst his apple-trees, insomuch that, 

 after a year or two, the most promising young plants either lose 

 whole branches or the trunk exhibits unsightly cavities which 

 at length, by their confluence, become so extensive as to impair 

 materially their fertility and ultimately to cause death. But 

 these are far from being the only cases ; and, unless I am greatly 

 mistaken, some affections which at first sight seem of a very dif- 

 ferent character are referable to the same group. Nor is the 

 disease confined to trees or the harder structures ; a very com- 

 mon form occurs on the fruit itself ; and such diseases as the Ta- 

 con, which is so fatal to the Saffron-growers in Prance, and has 

 lately done so much mischief amongst the cultivators of the fine 

 varieties of Gladiolus, appear to belong justly to the same ca- 

 tegory. 



In some cases, the Canker-patches affect at once the whole 

 circumference of the branch ; but far more frequently they are 

 scattered here and there, without one being able to give any 

 reason why one portion of the tree should be affected rather 



