CAUSE AND NATURE OF CROWN-GALL 15 



certain the communicability of the disease and the effect of 

 various fungicides and corrective measures upon it. 



In February, 1896, the first experiments were begun. The 

 orchard was a square forty. The trees were set twenty feet 

 apart and were five years from the nursery. Probably 85 per 

 cent., of the trees were more or less badly infested with crown- 

 gall. The soil was rather heavy, but uniform in character 

 throughout the orchard, and the surface practically level. In 

 order to make the work of as general an average as possible, two 

 rows of trees were selected for the experiments, one being 

 diagonal to the other. Row 16, counting from the east side of 

 the orchard and extending north and south, was examined and 

 the diseased trees treated with a fungicide. The work was 

 begun at the north border of the orchard and forty consecutive 

 trees of the above row examined. At the fortieth tree the 

 diagonal row extended to the northwest, thirty-one trees being 

 examined and treated. 



A detailed record was kept of the condition and general ap- 

 pearance of the seventy-one trees examined, as the crowns were 

 uncovered and the surface roots exposed. Photographs were 

 made illustrating exactly the condition of many of the trees and. 

 a record was made of the number, size, and position of the galls 

 on the surface roots and crowns. Of the forty trees examined 

 in row 16 thirty -four were more or less badly diseased. Twenty - 

 three of the thirty-one trees in the diagonal row were also affected . 



The diseased trees in row 16 were treated as follows: The 

 crown was exposed by carefully moving the soil. The exposed 

 galls were all removed and the wounds treated with Bordeaux 

 mixture. Afterward a coating of tar was applied and the earth 

 filled in about the trees. The trees in the diagonal row were 

 treated in a similar manner, with the exception that the wounds 

 were coated with paint instead of tar. 



These trees were examined in April and September, 1896 ; 

 February and May, 1897 ! September, 1898, and when the 

 orchard was visited in November, 1899, the trees that remained 

 alive were. being cut down and burned. As the complete his- 

 tory of each tree during the three years cannot be entered into, 

 I present the records that I have regarding a few of the treated 

 trees and the conclusions that the experiments seem to justify. 



