METHOD FOR THE COXTEOL OF CPvOWX GALL. 



graft 



This proved to be the case. In a number of experiments 

 performed in 19:25 complete conhrmation of results of experiments 

 initiated in 1921 with the formaldelnxle solution and in 19:^:3 with the 

 organic-mercury preparation has been obtained. In practically all 

 of these experiments the grafts were wrapped either with raffia or 

 with a cheap grade of muslin in such a manner as to cover completely 

 the graft unions. The trees were dug as 1-year grafts. Neither the 

 stand nor the amount of growth was reduced by the use of the or- 

 ganic-mercury compound as compared with untreated grafts grown 

 as checks. The trees were classified into three grades: (1) Galled 

 trees, with further subdivision into those with large and those with 

 small galls; (2) doubtful trees, that is. trees exhibiting symptoms so 

 slight as to be open 

 to question or dilier- 

 ence of opinion; and 

 (3) clean trees, that 

 is, those trees which 

 showed no symptoms 

 of gall or hairy-root. 

 It should be stated 

 that practically all of 

 the so-called doubtful 

 trees Avould have been 

 classified as clean 

 trees in an ordinary 

 inspection. The ac- 

 companying illustra- 

 tions were made from 

 photographs of 

 trees grown in the 

 experiments of 1925. 

 Figure 1 illustrates 

 examples of clean 

 trees. Figure 2 illus- 

 trates the t^'pe of 

 tree which has been 

 classified as possess- 

 ing a small gall, 

 whereas Figure 3 



illustrates two types of trees classified as having large galls, which 

 have invariably encircled more than 40 per cent of the circumference 

 of the tree. Figure 4 represents one of the types of trees classified 

 as doubtful. 



Table 1. — Comparisoji of results obtained ii-ith all grafts treated icith the 

 organic-mercury com}jound and untreated grafts grown as cheeks 



Fig. 2. — Type of tree classified as possessing a small gall 



Treated grafts 



Untreated grafts 





Number 



Percentage of galls 





Number 



Percentage of galls 





Large Total 



Large Total 



2,619... 





2. fi 1 



2.619 





28. 7 32. 6 







