BLIGHT. 139 



could be inoculated with blight, facts now strongly prove 

 that any supposed inoculation must have been simply a local 

 irritation that could not have resulted in blight. On the ist 

 of June I steeped blighted leaves, wood and bark in water, 

 leaving, them four days, until the liquid became dark red. 

 This was inserted freely into cuts made as for budding, and 

 the young pear shoots dipped into it. The experiments were 

 made on a three-year-old Bartlett, a five-year-old Idaho and 

 an eight-year-old bearing Le Conte. At this time, six weeks 

 after, there is not the slightest sign of blight on any of the 

 trees. At my request, Mr. E. W. Kirkpatrick, of McKinney, 

 in North Texas, and Mr. S. K. Wheeler, of Arcadia, in South 

 Texas, also vainly attempted to inoculate healthy trees with 

 blighted sap and bark, not a single case showing the slightest 

 effect. This demonstrates absolutely that this disease is of 

 internal origin, and results only when trees are subjected to 

 the aforementioned conditions. While I have suggested in 

 this chapter a preventive treatment for trees now growing, it 

 may be of doubtful value. No surface-rooted trees, like those 

 in nearly all pear orchards elsewhere, can keep the sap in free 

 motion during a severe drouth, especially if bearing a crop of 

 fruit. Even though not pruned or stimulated out of season, 

 much would depend on the character of the winter and spring. 

 Having now shown from the foregoing incontrovertible 

 facts that the bacterial disease of blight is of internal origin, 

 and the result of certain conditions, the question naturally 

 arises, May not other forms of bacterial tree diseases, such as 

 yellows, black-knot, root tumor, etc., be of similar origin? 

 Reasoning from analogy, we would naturally come to the same 

 conclusion, nor will any other theory cover the cases. All 

 such diseases must be the result of inherent weakness aggra- 

 vated by favoring conditions, and none will deny that the more 

 vigorous we can make our trees the less liable they will be to 

 attack. On this principle I have demonstrated that the viru- 

 lent root tumor of the South can be entirely cured by planting 

 affected trees in very small holes, after cutting off the roots 

 very closely and fertilizing them well. One thousand plum 

 trees thus treated four years ago were examined recently, and 



