THE CROWN GALL CONTROVERSY. 253 



the slime mould group. Unfortunately he did not prove to the 

 satisfaction of all that he had located the organism, and until 

 later experiments are performed the cause of crown gall must 

 remain a debatable question. 



IS CROWN GALL COMMUNICABLE? 



According to the great preponderance of evidence this ques: 

 tion should undoubtedly be answered in the affirmative. Pro- 

 fessor Heald of the University of Nebraska has succeeded with 

 very little difficulty in producing the galls upon perfectly 

 healthy raspberry plants by inoculating the crown of the root 

 with bits of crown gall. Professor Selby in bulletin 121 of the 

 Ohio Experiment Station, says " soil which causes this sort of 

 growth upon peach trees has been known to produce the same 

 upon the apple and conversely." And in bulletin 111 he gives 

 as a result of an experiment carried on by the Ohio station 

 that peach trees set in a raspberry plantation affected with 

 crown gall became attacked by crown gall to the extent of 70,8 

 per cent, in two years. Professor Toumey of the Arizona 

 Station was able to transfer the disease from seedling to seed- 

 ling with ease, and found that almond seedlings grown in soil 

 into which minced galls had been introduced, showed a larger 

 percentage of infected trees than similar seedlings grown in 

 soil where the minced galls were absent. In opening bundles of 

 trees where there are trees infected with crown gall, it has often 

 been noticed that several diseased trees would be found 

 together, indicating that they were near each other in the nur- 

 sery row. All these examples tend to show that from what is 

 known at present crown gall should be looked upon as com- 

 municable. 



HOW MUCH DAMAGE DOES CROWN GALL DO? 



Our authorities are divided upon this point also. The botanist 

 of the Michigan Experiment Station in bulletin 25 says: "The 

 effect of this disease upon the tree is to produce a spindling or 

 stunted growth and usually leads to the death of the tree. 

 Trees affected with crown gall when planted from the nursery 

 seldom reach bearing size, but frequently die the first season. " 

 On the other hand a nurseryman in writing to the New York 



