26 CAUSE AND NATURE OF CROWN-GALL 



EXPERIMENTS IN INOCULATING SOIL WITH MINCED GALLS 

 IN 1898-1899. 



Although the experiments with seedlings in the green-house 

 the previous year clearly indicated the infectious character of 

 the crown- gall, the almond was the only tree experimented with. 

 As the disease occurs upon a great variety of trees, a series of 

 experiments were undertaken in 1898 in order to ascertain if 

 the disease occurring on the almond could be communicated to 

 the peach, apricot, apple, grape, and other plants. I also de- 

 sired to duplicate my experiments of the previous year and to 

 vary them somewhat before drawing definite conclusions respect- 

 ing the communicable nature of the disease. Therefore, on Jan- 

 uary 5, 1898, thirty-four rows of various seeds were planted in 

 the green-house in freshly prepared soil. Twenty-five seeds 

 were planted in each row, unless otherwise stated, and the seeds 

 used, with the exception of those planted in rows 6 to 11, in- 

 clusive, were obtained from non-infested plants. Rows 1 to 5, 

 inclusive, were planted with almonds. The purpose of this 

 planting was that the resulting seedlings might serve as a check 

 on other plantings, and that healthy seedlings might be secured 

 for inoculation experiments the coming fall. Rows 6 to 11, in- 

 clusive, were also planted with almonds. The seeds used for 

 these rows were, however, obtained from a badly diseased tree 

 and were not allowed to come in contact with the soil in the 

 orchard before collecting them. Rows 12 and 13 were planted 

 with apricots, and rows 14 and 15 with peaches, all under nor- 

 mal conditions. Rows 16 to 22, inclusive, were planted with 

 almonds. In rows 16 to 19, inclusive, about one quart of 

 minced galls from the Glendale orchard was mixed with one- 

 half pound of bluestone and placed in the rows with the seeds 

 which were planted as in the experiments of the previous year. 

 In every instance boards were placed between the rows, repre- 

 senting different conditions of planting and soil infection. In 

 rows 20 to 22, inclusive, minced galls were mixed with one- 

 fourth their weight of a mixture of bluestone, copperas, and 

 quicklime in the following proportions, namely : Two parts of 

 bluestone, one part of copperas, and three parts of quicklime. 



