58 CAUSli AND NATURE OF CROWN-GALL 



Carelessness on the part of orchardists, at least to some extent, 

 accounts for the wide dissemination of crown-gall in the Salt 

 River Valley. The following specific example is suggestive : 



The diseased trees dug up at the Glendale orchard were cut 

 into stovewood and sold to various farmers throughout the 

 neighbcrhood. 



The stumps of these trees had a great man}' large galls upon 

 them, as shown in Fig. 30, and in the transportation of this 

 wood the galls became scattered throughout the neighborhood. 

 It hardly seems necessary to suggest that all galls should be 

 carefully gathered and burned when removed from the trees, 

 and that the diseased trunks should never be removed from the 

 premises. 



LOSSES CAUSED BY CROWN-GALL. 



With a plant disease that has been so little studied and so 

 little understood, it is not possible to arrive at definite conclu- 

 sions concerning losses incurred. From its wide dissemination 

 and the great variety of economic plants that it infests, the 

 yearly losses caused by it must be very great. As the disease 

 usually attacks its host-plant underground, it has frequently 

 been overlooked by the fruit-grower and has not received the 

 attention that it merits. Thousands of trees have dwindled and 

 died or have failed to fruit or make a desirable annual growth 

 of wood without the owner recognizing the source of the trouble. 

 After carefully examining hundreds of trees in many different 

 orchards during the past seven years, I am convinced that at 

 least in Salt River Valley much of the trouble can be directly 

 credited to crown -gall. 



Fig. 31 shows the present condition of an almond orchard at 

 Glendale, Arizona, that four years ago, at first appearance, im- 

 pressed me as being one of the finest and most promising almond 

 orchards that I had ever seen. Although at that time the trees 

 were badly diseased, but little evidence of it appeared above 

 ground. With each succeeding year a greater number of the 

 trees died outright or broke off at or just beneath the surface of 

 the ground, where developing galls had gradually weakened 

 the stem. A very conservative estimate would place the losses 



