DISEASES OF THE PLUM 1195 



they are in poor condition and of inferior quality, or may be an 

 entire loss. 



Diseased plums may fall or they may cling to the tree; in either 

 case they shrivel, due to the loss of water, and become the 

 mummy " so familiar to orchardists. It has been stated that 

 the summer spores may live over winter. In this connection it 

 should also be borne in mind that the fungus also passes the 

 winter in the mummies just mentioned. From the mummies, 

 which cling to the tree throughout the winter, there is developed, 

 in the spring, a new crop of the summer spores. These infect 

 the blossoms and young fruits. From the fallen mummies in 

 the spring, there arise cup-shaped, stalked bodies. These organs 

 furnish another kind of spores, known as ascospores, for the spring 

 infection of blossoms. 



The diseased blossoms become brownish and often are confused 

 with frost effects. The causal fungus may spread from infected 

 blossoms to adjacent twigs through the flower stalks. Twigs and 

 limbs may also become diseased from the infected fruit, the fungus 

 growing directly through the fruit stalk into these organs. The 

 twigs and limbs are also infected through wounds in the bark. 



The control of plum brown rot, based on the foregoing state- 

 ments, proceeds as follows : The fruit should be protected by spray- 

 ing with lime-sulphur solution, 1-50. Since moisture is highly 

 favorable to the disease, the tops of the trees should be so primed 

 us to admit sunshine, the heat of which evaporates the moisture. 

 The fruits should be thinned so that no two touch, for, it will be 

 remembered, the fungus is able to travel from one plum to another 

 if the fruit hang in clusters or touch one another. The extermina- 

 tion of mummies, in which the fungus hibernates, is doubtless 

 of some value; this method alone fails in that the complete 

 destruction of all the mummies is never accomplished. 



LEAF SPOT 



This disease is caused by Coccomyces prunophorce Higgins. 

 Many of the stone fruits suffer from fungi which produce a shot- 

 hole trouble. In such cases the leaf is killed in more or less 

 circular areas, which dry up and fall out, leaving a shot-hole 



