A Bacterial Disease of Stone Fruits 417 



Still the writer has frequently olDtainecl cultures of the organism from 

 both feeding and egg punctures of curculio on fruit, and in a number of 

 cases it has been practically certain that the insect was the agent of in- 

 oculation. 



Infected leaves are often l^lown about by the wind, and no doul^t are 

 sometimes responsible for the occurrence of primary infection. Yet 

 danger from this source is comparatively .slight, since the leaves soon dry 

 out and the bacteria quickly lose their vitality. The disease usually 

 advances in the orchard in all directions from a center of infection, often 

 forming a more or less circular diseased area. After the organism has 

 become established, the movement of limbs and branches caused by high 

 wind during storms also furnishes a means of conveyance for the bacteria 

 from diseased to healthy organs. 



Old neglected trees, the plum in particular, often serve as sources of 

 inoculum. In the past seven years two outl^reaks of the disease on the 

 Missouri State Fruit Experiment Station grounds were traced directly 

 to infected Burbank, Abundance, and Golden plum trees. 



Where the organism has become well established, diseased trees may serve 

 as a source of inoculum and young trees planted in adjoining fields grad- 

 ually become diseased. In 1906 a very striking case of this sort came under 

 observation. A tract of one hundred and sixty acres of land on the east side 

 of an old peach orchard at Koshkonong, Missouri, which contained many 

 infected trees, was planted in the spring with two-years-old Elberta peach 

 trees. In October the fohage and twigs of the trees in the ten rows next 

 to the old trees were badly diseased. During 1907 the organism gradually 

 advanced, and by the close of the season the trees in one hundred and ten 

 rows were infected. The disease, however, was much worse in the first 

 thirty rows than in the others. During 1908 the organism spread entire!}^ 

 across the orchard and every tree in the entire tract was injured to a greater 

 or less extent. The trees in the first thirty rows next to the old orchard 

 suffered most severely, and many of them were permanently injured. 



Man himself is often an important agent of inoculation. In selecting 

 material for budding, nurser;yiiien frecjuently cut twigs from diseased 

 trees, and thus, by inserting the infected bud material, inoculate the 

 stock. 



In 1907, on the Missouri vState Fruit Experiment Station grounds, 

 several thousand healthy peach seedlings were budded with buds taken 



