374 



STATE BOARD OF AGRICULTURE. 



Fig. 24. — Leaf plum affected with the shot hole fungus. 



GUMirOSIS OR GUMMIXG OF .STONE FRUIT.S. 



The flow of gum from liranches of plum, peach, cherry, almond, etc., has in 

 some cases been attributed to the presence in the tissues of a parasitic fungus. 

 Thus Massee describes a gummosis of the flowering almond due to the attacks 

 of Cladosporiiim epipJujUum and a similar trouble on the same plant has beeu 

 noted by the writer under the head of Brown Rot of Plum (Sclerotinia fructi- 

 gena) . 



Cladosporiiim epiphyUum has also been found causing gummosis on the purple- 

 leaved variety of the Myrobalan plum grown for ornament at the Agricultural 

 College while the same disease on cultivated plums has been found to be asso- 

 ciated with a species of Cladosporium. In many cases the trouble probably begins 

 in some crack or wound which allows the fungous parasite to gain an entrance. 

 The presence of the mycelium induces a flow of sap which exudes and hardens 

 forming tear-like drops, sometimes of considerable size. This gum is partly 

 utilized by the fungus in the production of more spores. The portion of branch 

 beyond the affected spot may in some cases be killed or permanently weakened. 

 In such cases the branch should be cut off below the diseased area and burned. 

 The use of fungicides will serve to reduce the tendency toward gumming. 



Boring insects of the peach, plum and cherry may also cause a flow of gum 

 from the wound made in entering and these wounds probably often serve to 

 allow the entrance of fungi, hence the desirability of combating the insect enemies 

 of these trees. 



