750 ANNUAL, REPORT OF THE Off. Doc. 



"This latter proposition of course is radical and is going perhaps 

 to the extreme of caution, still if a man is setting out an orchard on 

 good land he very naturally wants to take every precaution to get 

 healthy trees. The Department, as well as some of the Stations, 

 is studying this disease along the same lines as Prof. Toumey, and 

 we hope to obtain some more definite information than we have at 

 present. The practice of grafting on pieces of root so that the cal- 

 lus is about on or below the surface of the ground, is probably re- 

 sponsible for a great deal of crown gall. We have observed, and I 

 think it is the general conclusion of all who have studied the ques- 

 tion, that the callus offers a most favorable location for the devel- 

 opment of this crown gall parasite. In fact, the parasite seems to 

 get in nearly always through some serious wound at this portion of 

 the tree, or through the callus made by grafting. It seems quite 

 likely, though the matter has not received sufficient investigation 

 yet to make a definite statement, that if whole roots could be used 

 and budded instead of grafted, that there would be less danger of the 

 development of this disease and especially less danger of its ob- 

 taining a foothold in the more vital portions of the tree. 



"In conclusion, therefore, you will see that no fixed and positive 

 statement can be made regarding the question of using or discarding 

 the trees. For my own part, if I were to answer your question No. 

 23 in the program, I should say, "No, do not plant trees that are 

 visibly affected with crown gall." 



"Trusting this information may be of some service in your discus- 

 sion, I am, 



"Very truly yours, 



"A. F. WOODS, 

 "Pathologist and Physiologist, 

 "IT. S. Department of Agriculture." 



Mr. Wertz asked Prof. Johnson's views on the subject under dis- 

 cussion. 



PROF. JOHNSON: The question has been so ably answered in the 

 paper just read, and my views are so fully embodied in Prof. Woods' 

 paper, that but little need be added. As stated by Prof. Woods the 

 subject is being investigated by the Department of Agriculture at 

 Washington, and in his opinion it may be eliminated or controlled. 



It is almost impossible to find a locality where this disease does 

 not exist. Its nature and origin seem considerable of a mystery. 

 In Central Illinois it is a verv serious matter, and some.mav be ob- 

 liged to go out of business. I have made some experiments with 

 infected trees, and the results show that they are dwarfed in growth 

 and shorter lived. It is most likely to attack trees at the point of 

 union between graft and root. A two and one-half per cent, solu- 

 tion of formalin used as a dip, has given satisfactory results. 



