318 Report of the Horticulturist of the 



varies according to the natural susceptibility of the variety to its 

 attacks; that with any given variety it varies in different locali- 

 ties and in different seasons, and that the conditions of light, tem- 

 perature and moisture, especially when the fruit it setting, have 

 much to do with the prevalence of the disease. 



So far as known to the writer, it has never been shown that the 

 composition of the soil influences in any perceptible degree the 

 susceptibility of the foliage and fruit to attack of the scab except 

 as it affects the amount of moisture. Whether the ability of 

 the foliage and fruit to resist the scab may be increased by the 

 application of a certain class of fertilizers to the soil, or whether by 

 the use of certain other kinds of fertilizers the liability to injury 

 from this disease may be increased, are questions which have per- 

 plexed the minds of thoughtful fruit growers. Joseph Harris 

 brought up this question in a paper on fertilizers at the 1891 meet- 

 ing of the Western New York Horticultural Society.* He said: 

 " I cannot but think that anything calculated to increase the 

 growth, vigor and luxuriance of the trees will render them less 

 liable to injury from fungous diseases. If this is true then fer- 

 tilizers will help us." 



In a discussion in the same societyf in 1893 the idea was ad- 

 vanced that trees may be fed so as to fit them to resist fungi; 

 that too liberal use of highly nitrogenous fertilizers, such as stable 

 manure, fosters conditions which render the trees more liable to 

 injury from fungous diseases, and that such tendencies may be 

 corrected by the use of plant food containing more potash and 

 phosphoric acid. Some were inclined to think that the applica- 

 tion of hard-wood ashes to the soil increased the ability of the 

 tree to resist the scab. In order to discover whether liberal ap- 

 plications of hard-wood ashes to the soil would have any percep- 

 tible influence on the immunity of the foliage and fruit from the 

 scab fungus, an investigation was started at this Station in 1893 

 which has continued to the present time. The results are here 

 offered as a contribution to our knowledge on this subject. 



•Proc. W. N. Y. Hort. Soc, Rochester, 1891, p. 100. 



tProc. W. N. Y. Hort. Soc, Rochester, 1893, pp. 19, 140, 141. 



