THE NEW YORK APPLE-TREE OAI^KER. 



Wendell Paddock. 



SUMMARY. 



Attention has but recently been called to this canker of apple 

 trees, probably because the injuries were thought to be due en- 

 tirely to sun scald. 



Experiments extending through two seasons prove that this 

 canker. is caused by attacks of Siihaeropsis malorum Pk. (see p. 

 355), the fungus that causes the black rot of apple, pear, and 

 quince fruits. The experiments also indicate that this fungus 

 occurs on a number of other plants. 



This disease is widely distributed in the orchards of the State 

 as well as in those of adjacent States. In many instances it has 

 been very destructive. 



By way of treatment it is recommended : That the trees be 

 kej)t in tlie best growing condition ; that cankered limbs be re- 

 moved where practicable ; that the trees be sprayed with Bordeaux 

 mixture as recommended on page 343 ; and that in some instances 

 the trunks and larger limbs be scraped and washed as recom- 

 mended on page 343. 



CANKER.— WHAT IS IT? 



The term canker, as applied to plant diseases, has been in use 

 in Europe for a long time, where it is commonly used to desig- 

 nate the injury done to trees by species of Nectria. (See Plate 



Reprint of Bulletin No. 103. 



