THE NEW YORK APPLE-TREE CANKER.” 
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 Sphaeropsis 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 
kept in the 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. 163. 
