APPLE CANKER. 



MERICAN APPLE CANKER {Spha- 

 ^^ eropsis malorum. — The popular edi- 

 6S tion of Bulletin 185, Geneva, New 

 ^^^r York, is devoted to this subject. 

 The disease has become very prevalent in 

 Nova Scotia and not infrequent in Ontario, 

 where it has been attributed 

 to sun-scald, frost, etc., 

 when in fact it is a fungus 

 growth. It is therefore in 

 place to give the following 

 extract : 



"To cause the destruc- 

 tion of cankers which girdle 

 the limbs, the germs of the 

 disease must get through 

 the tough outer layer of the 

 bark into the growing layer 

 beneath, the cambium. An 

 injury to the bark of some 

 sort is necessary to this 

 entrance; for the fungous 

 threads can not penetrate 

 the unbroken bark. Sun- 

 scald, as well as mechanical 

 abrasions, may cause such 

 injuries. The bark is killed 

 by the sun and frost, and 

 cracks or peels, when the 

 germ finds ready entrance 

 and rapidly extends the in- 

 injured area in canker form. 

 Sunscald or sunburn is 

 a common trouble in this 

 state, probably more com- 

 mon than generally sup- 

 FiG. 2127. posed, especially on tender 

 American Apple varieties. The long areas 

 of reddish bark on the south 

 and southwest sides of limbs and young 

 trunks are inconspicuous when they first 

 are scalded and so escape notice ; but 

 they are all too common, and may be- 



come the seat of serious harm to the trees. 

 Trees of tender varieties should be protected 

 from the direct rays of the sun by training 

 them to low, thick heads which shade both 

 trunks and branches. Additional protection 

 may be given by a coat of whitewash upon 

 the trunks ; which helps to prevent absorp- 

 tion of the sun's rays and also exerts a 

 favorable influence upon the bark itself. A 

 good mixture is : 



Lime (unslaked) 30 lbs. 



Tallow 4 " 



Salt.... 5 " 



Dilute with water enough to make i 

 spray easily. 



Treatment of canker.- — ^In addition to the 

 protection from sunscald, thorough spraying 



Fig. 2128. European Apple Canker. 



