798 ANNUAL REPORT OF THE Off. Doc. 



orowii gall or hairy root on the seedling stocks for grafting or bud- 

 ding. Second, we have advocated in a recent paper before the Ap- 

 ple Growers' Congress the trial of disinfection of apple seedlings 

 before grafting. This matter has not been put to the test as yet 

 , and, therefore, too new to recommend in commercial work. The 

 material which we shall try for disinfecting consists of formalin di- 

 luted at the rate of one pint to thirty gallons of water. Third, ap- 

 ple nurseries should be planted out on land which has not been in 

 nursery stock for several years, or, if possible, land which has not 

 been planted to the apple or perhaps other fruit trees for some time 

 previous. 



"Yours very truly, 



"M. B. WAITE, 

 "Pathologist in Charge of Investigations of Diseases of Orchard 

 Fruits." 



PROF. VAN DEMAN: In some parts of the West nurserymen have 

 had serious trouble with crown gall. Trees may be infected when 

 grown in nursery blocks, and even in seedling beds. I have seen the 

 disease on seedlings when brought to the grafting table, and it may 

 be transmitted from root to root by the grafting knife. The union 

 of root and graft is the most vulnerable point, and if germs are in 

 the soil, the trouble will likely first manifest itself at that point. 

 Again, a tree may be entirely free, and if set in an orchard where 

 infected trees have stood, it will readily take the disease. 



DR. FUNK: Where the hairy root is in evidence do we not usually 

 find wooly aphis? 



PROF. VAN DEMAN: The knots or growth caused by wooly aphis 

 are distinct from crown gall. I do not think wooly aphis causes 

 hairy root. 



PROF. BUTZ: You can always satisfy yourself whether it is 

 crown gall or woolly aphis, by cutting with a knife. In the former 

 the gall is hard and woody, in the latter it is soft. Hairy root is 

 most likely to be found in wet soil, but we do not find any enlarge- 

 ment except where crown gall exists. 



MR. BRINTON: Some 45 years ago Mr. Thos. M. Harvey conducted 

 a nursery and had some of the worst cases of crown gall I ever 

 saw. He sold trees all over Chester and Lancaster counties, and 

 some of the best orchards grew from those trees. His manager said 

 the trees would come all right and they apparently did. I saw in 

 West Chester nurseries 20 years ago the worst cases of woolly aphis 

 I ever saw, and the following year there was none to be seen. It 

 seems to be the case with insects frequently, that they come and go 

 without any apparent cause, or effort to destroy them. 



