254 MASS. EXPERIMENT STATION BULLETIN 194. 



The Relation of Variations in Fertilizer Application to Rust. 



In the brief statement of the objects in view in the fertihzer experiment, 

 already given, occurred the phrase: "... to include . . . studies 

 ... of effects of the varied treatments upon: ... (2) the plant as 

 influencing the character of its development, its phj^siology and its 

 health." 



In this brief reference I had in mind particularly any influence upon 

 the extent of injury from rust, which at the time the experiments were 

 planned was the only disease of asparagus which was proving at all 

 serious. This line of investigation was suggested by the fact that numer- 

 ous investigators had become convinced, as a result of their studies, that 

 variations in the kinds, amounts, and perhaps also in the seasons of 

 application, of chemical fertihzers had an important relation to the 

 capacity of different cultivated plants to resist disease. One of the 

 earliest in this country to believe this, both from liis study of results 

 obtained through the experience of others and from experiments conducted 

 by himself, was the late Dr. C. A. Goessmann, who became convinced 

 that peach yellows could be prevented by suitable applications of potash.^ 



It is not possible to demonstrate by means of figures showing the yields 

 of commercial asparagus in the experiments in Concord that such varia- 

 tions in fertUizer treatment as were made in those experiments either did 

 or did not affect the amount of rust. The principal reason why this is 

 true is because the attacks of rust were determined chiefly by the location 

 of plots both as to direction and distance from sources of infection, — in 

 other words, from fields of the old and highly susceptible varieties of 

 asparagus found in various parts of the district in Concord in which our 

 experiments were located. It was impossible, therefore, to measure in 

 figures any difference which might have been caused by variations in 

 fertUizer treatment. 



My conclusion, however, based upon frequent examinations of the 

 growth, especially subsequent to the end of the cutting season when the 

 tops and foliage were developing or fuUy developed, was that there was 

 no influence on the amount of rust that could be attributed to a difference 

 in the kind of chemicals used in the experiments. On the other hand, 

 my examination of the plots — most important, the one made in late 

 September in 1911, the year of the heaviest infestation of rust — led to 

 the conclusion that variation in the time of apphcation of the nitrate of 

 soda did have considerable effect. At my request Mr. J. B. Norton, who 

 saw the bed much more frequently than I, made a particular point of 

 attempting to trace any effect of rust due to variation in fertUizer treat- 

 ment. Mr. Norton, working entirely independently and without knowing 

 what differences if any I had noticed, agreed with me almost absolutely 

 as to relative amounts of rust on different plots. Our conclusion was 



» Agriculture of Massachusetts, 1881, p. 84; 1882, p. 440; 1883, p. 360. 



