170 EXPERIMENT STATION. [Jan. 



of an orchard 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. Remedial measures consist in prun- 

 ing off the knots and l)urniiii:, iiud it has been advised that they 

 l)e cut out when young, and the exposed area coated with paint. 

 Observations and experiments have showm that early spring 

 spraying materially lessens the infection. 



Plum Leaf Spot or Shot Hole (CyVindrosporhim Padi, 



Karst). 

 This disease causes spots on the leaves somewhat circular in 

 outline, which often become joined. These affected parts 

 usually have a reddish outline, and finally the diseased tissue 

 turns dark browai 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 

 mu(di weaken the tree and eventually kill it, but if lime sul])hur 

 is used thoroughly, little trouble will be experienced from this 

 disease. This same disease also affects the cherry. 



Peacti Shot Hole (Cercospora rlraim.<tcissa, Sacc). 

 The effects of this disease resemble those caused by CyUndro- 

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

 liranches are also attacked, often causing a great nund)er of the 

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

 curl. 



Sliof TTolc Effect caused hy improperly mixed Bordeaux. 



When im])roperly 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 como out on the now shoots reinain unaffected, 



