326 



canker, nevertheless, they are interesting. Parliinson (1629)' in a rare 

 volume discusses canker after the following manner: "The canker is a 

 slirewd disease when it hapijeueth to a tree; for it will eate the barka 

 lound, and so kill the very heart in a little space. It must be looked into 

 in time befoi'e it hath runne too farre; most men do wholly cut away as 

 nnuh as is fretted with the Canker, and then dresse it, or wet it with 

 vinegar, or Cowes dung and urine, etc., until it be destroyed, and after 

 healed againe with your salve before appointed * * *."' Hales (17;12)- 

 wrote iu regard to the manner in which canker spreads. Marshall? 

 (ITitO)' says: "The canker is a disease that originates ehietiy in the soil, 

 pervades the juices of the plant, and tinally operates towards its dissolu- 

 tion." 



Other workers have discussed canker, but I'adibck ("OSj' was first 

 to present anything definite regarding the New York apple tree canker. 

 Mangin ('02)^ and Delacroix ('03)'' described an apple disease. Until 

 recent years there has been confusion as to the cause of the leaf-spot or 

 "frog-eye" disease, but Sc-ott and Rorer ('OS)' proved its identity with the 

 canker disease. 



GeoffraijJiical Distribution. — The disease is known to occur in Eng- 

 land, France, Austria, Italy, probably in Scotland, South Africa and in 

 America. In our country it is found in practically all apple growing dis- 

 tricts. 



Economic Importance. — From careful conservative estimates it has 

 been determined that this disease is second in importance among the fun- 

 gous disea.ses of the apple. The annual loss can be safely put at $10,000,- 

 000, which makes it apparent that the disease is a serious one. 



Symptoms. — The first signs of canker are usually the dying out of the 

 top of affected trees (Fig. 1). Upon approaching more closely, the 

 bai'k is found to be roughened in more or less definite areas (Fig. 2). 



'1629. Parkinson, Jjhn. Pardisus Terrestris, London. 1629:.5.'0. 



'17.32. Hales, Stephen. Statical Essays. 1732:264-265. 



• 1799. Marshall 7 An Inquiry into the Cause of Diseases in Plants with Hints Respecting their 

 Cure or Prevention. Edinburg (J. Ruthven and .Sons). 1799:24. 



•'98. Paddock, W. An .\pple Canker. Science n. s. 8:.i9.5-596. 1898. 



•'02. Mangin, L. Sur une nouvelle maladie dcs Pommiers causee par le "Diplodia pseudo- 

 Diplodia." Jour. d'Agr. Prat. 2:138-139. 1902. 



'03. Delacroix, G. .Sur un chancre du Pommier produit par le .Sphaeropsis malorum Pk. Bull. 

 Soc. Myc. France. 19:132-142. 1903. 



''08. Scott, W. M. and Rorer, J. B. .\pple I,eaf-Spot Caused by Sphaeropsis malorum. U. S. 

 D. A., Bu.Pl.Ind.BulI. 121:48. 1908. 



