EXPERIMENT STATION BULLETINS. 



371 



centers of infection. Furthermore, the mycelium which has caused the knot 

 is capable of spreading into any new shoots which may arise near it. Sometimes 

 trees become so badly infested with this disease as to present a mass of knotted 

 limbs which have just enough vitality to i)ush out a few leaves and riiake a feeble 

 growth, while many of the branches die each season. 



Treatvient. — As the knots form early in the growing season they should be re- 

 moved at once and not left to produce spores. The branch bearing the knot should 

 be cut several inches below the swelling to remove all mycelium. Burn the 

 knots as soon as removed. While the thorough removal of the knots will usually 

 serve to keep this disease in check it may be advisable to spray with some 

 fungicide especially if there are wild cherry trees or other plum trees in the 

 neighborhood on which the disease is allowed to exist. 



BROWN ROT. 



(Sclerotinia fructigena (Kze. & Schm.) Norton.) 



This fungus undoubtedly destroys more plums thany any otlier one disease. 

 It is also very destructive to peaches, especially the early varieties which fre- 

 quently rot badly on the trees and in transportation and storage. The cherry 



".Fig. 22. — Plums affected with brown rot found on trees in February, showing mummified con- 

 .dition. These plums still retain the ability to give off spores (conidia). 



