CAUSE AND NATURE OF CROWN-GALL 



27 



The Milestone and copperas were crushed to a fine powder, 

 thoroughly mixed with the lime after slaking, and enough water 

 added to form a paste. This paste was mixed with the minced 

 galls and placed in the drills with the seeds. Rows 23 to 25, 

 inclusive, were planted with almonds ; 26 and 27 with peaches ; 

 28 and 29 with apricots ; 30 and 31 with English walnuts ; 32 

 with prunes ; 33 with grapes, and 34 with apples. Minced 

 galls from the Gleudale orchard were placed in the drills with 

 the seeds in all the rows from 23 to 34, inclusive. 



As in the previous year, a portion of the seedlings damped 

 off soon after coming up. A sufficient number, however, re- 

 mained alive to give value to the experiment. They were 



Fig. 8.— Almond seedlings from a single row, showing the relative number of dis- 

 eased to undiseased trees, in soil previously inoculated with minced galls. 



harvested October 26, 1899. The thirty-seven trees obtained 

 from rows 1 to 5, inclusive, had no galls upon the roots or 

 steins. The eighty-three trees which grew in rows 6 to 11, in- 

 clusive, also showed no galls upon them, and as the seeds from 

 which these trees grew were obtained from a tree with badly 

 diseased roots it clearly shows that the infection is local and 

 cannot be carried by the seed. This inference is confirmed by 

 the recent experiments of Halsted. No galls were found on 

 the nine apricot and eleven peach trees grown in rows 12 to 15, 

 inclusive. Only three plants with galls upon the roots were 

 found among the nineteen trees which grew in rows 16 to 19, 

 inclusive, which were treated to minced galls and bluestone, 

 while only one diseased tree was found among the twenty-four 



