206 



THE MONTHLY BULLETIN. 



disease only rarely caused serious trouble in the cherry orchards, 

 although a few cases have been observed where the disease was especially 

 virulent. 



Plums, peaches, almonds and apricots are often severely diseased. 

 Different varieties of peaches, Muir, Salway and Lovell, have been arti- 



FiG. 72. — Peach limb artificially inoculated with the 

 crown gall organism February 15, 1912. Photo- 

 graphed February, 1916. (Original.) 



ficially infected, as well as the different varieties of almond that are 

 used as rootstocks. Much more resistance is shown among plums, 

 especially the German prune and Damson, while the Myrobalan, whicli 

 is a popular rootstoek, is more readily infected. Orchards of peach and 

 almond often show a high percentage of diseased trees, and there is 

 little chance of a badly infected tree outgrowing the disease. 



The English walnut is susceptible to the disease when on English 

 roots, as much as 50 per cent of nursery trees being sometimes affected. 



