170 EXPERIMENT STATION. [Jan. 



of an orclmrd that one should be careful not to bruise or injure 

 the trees. 



The wind is probably the greatest agent for conveying the 

 spores from tree to tree. Eemedial measures consist in prun- 

 ing off the knots and burning, and it has been advised that they 

 be cut out when young, and the exposed area coated with paint. 

 Observations and experiments have shown that early spring 

 spraying materially lessens the infection. 



Plum Leaf Spot or Shot Hole (Cylindrosporkim Padi, 



Karst). 

 This disease causes spots on the leaves somewhat circular in 

 outline, which often become joined. These aifected parts 

 usually have a reddish outline, and finally the diseased tissue 

 turns dark brown and falls out. The leaves turn a yellowish 

 color and often begin to fall in July, but the most severe defo- 

 liation usually occurs in August and early in September. The 

 great loss from this disease is caused by defoliation before the 

 tree stores up sufficient starch and ripens its wood enough to 

 enable it to stand the cold of winter. Continual attacks very 

 much weaken the tree and eventually kill it, but if lime sulphur 

 , is used thoroughly, little trouble will be experienced from this 

 disease. This same disease also affects the cherry. 



Peach Skot Hole (Cercospora circumscissa, Sacc). 

 The effects of this disease resemble those caused by Cylindro- 

 sporium of the plum. The diseased spots fall out. and the small 

 branches are also attacked, often causing a great nundier of the 

 young shoots to die. Spray with lime sulphur, as for j^each leaf 

 curl. 



Shot JTolc Effort caused hy improperly mixed Bordeaux. 



When improporh^ mixed Bordeaux is used for a summer 

 spray, we invariably find the leaves badly riddled with holes, 

 due to the burning of the tissues. One can readily distinguish 

 this type of shot hole from those previously described, for the 

 leaves which come out ou the new shoots remain unaffected, 



