326 



cankor, novortlu'lcss. they are interesting. I'ai-lunson (1029)' in a rare 

 \(^luiiH' (lis<-nss('s canker after tlic r<ill<)\\iim iiininici': "'i'lie canlier is a 

 slircwd disease wlieii it hajipenetli to a tree; for it will eate the barka 

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

 in tin'.e i)el'(>i-e it liatli ruiiiie t(ii) larre; most men do wholly cut away as 

 much as is fretted with the ("anker, and then dresse it, or wet it with 

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

 healed a^'aine with your salve before appointed * * *." Hales (17;il2)- 

 wrote in regard to the manner in wliich canker spreads. Marshall? 

 (1799)'' says: "'I'he canker is a disease that originates chiefly in the soil, 

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

 tion." 



Other workers have discussed canker, but I'addi:c-k CDS)' was first 

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

 Maugiu ('02)" and Delacroix ('()3)'' described an apple dfsease. ITntil 

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

 "frog-eye" disease, but Scott and R<jrer ('08)' proved its identity with the 

 caidcer disease. 



Geographical 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 Iiitportancc. — From careful conservative estimates it has 

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

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

 0(X), which makes it apparent that the disease is a serious one. 



l^i.Ditptotiis. — The first signs of canker are usually the dying out of the 

 top of affected trees (Fig. 1). Upon ai)i)roaching more closely, the 

 bark is found to be roughened in more or less delinite areas (Fig. 2). 



'1629. Parkinson, J ihn. I'anlisus 'IViri'sUis, London, l(i29:o,"0. 



'1732. Hales, Stoplicn. Statical K.s.siiys. 1732:2()4-2ti5. 



•1799. Marshall? An Inquiry into the Cau.si- of Diseases in Plants with Hints Hespect ins their 

 Cure or Prevention. Kdinburg (J. Iluthvcn and Sons). 1799:24. 



•'98. Paddock, W. An Apple Canker. Science n. 9. 8:595-596. 1898. 



•'02. Mangin, L. Sur une nouvelle inaladie des I'omniiers causee par le "Oiplodia pscudo- 

 Diplodia." Jour. d'Asr. Prat. 2:l{8-i;ii). 11)02. 



•03. Delacroix, G. Sur un cluincn^ dii Poiiunier produil par Ic Spliacropsis iiialoruiii Pk. Bull. 

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



''08. Scott, \V. M. and Horer, .1. M. Apple I.i-af .Spot Caused by Sphacropsis lualoruni. I'. S. 

 D. A., Hu. PI. hid. Hull. 121:IS. HKIS. 



