508 Report of the Mycologist of thb 



Rows a were planted with badly diseased tubers. 



Rows h were planted with healthy portions of diseased tubers; 

 that is, the pieces planted showed no brown spots. 



Rows c were planted with tubers which showed only a trace of 

 the disease. 



Rows d were planted with healthy tubers. 



All conditions of soil, cultivation and amount of fertilizer were 

 as nearly as possible the same. The same variety, Grreen Mountain, 

 was planted throughout. The small yield is due, in part, at least, 

 to attacks of blight, Phytoplithora infestans, which killed the tops 

 prematurely. This, however, does not affect the experiment, be- 

 cause none of the tubers rotted, and on account of the alterna- 

 tion of rows of badly diseased seed with rows of slightly diseased 

 seed it is not likely that blight injured the one more than the 

 other. 



It is to be regretted that the check of perfectly healthy seed 

 was not larger. Being so small it is of no value and will not be 

 considered. The whole experiment is on too small a scale; but 

 since it is so planned that all conditions (save the amount of dis- 

 ease in the seed) are parallel, and the results are so marked and 

 so consistent with themselves, the experiment is worthy of con- 

 sideration. 



First, let us compare rows a and &, Rows a were planted with 

 badly diseased tubers. Rows 6 were planted with healthy part of 

 diseased tubers. With the exception of rows 7, 9, 19 and 21 the 

 yield of 6 was larger, proportionately, than a. In five cases the 

 eighty-eight feet of b yielded more than the one hundred feet of a. 



Second, let us compare rows a and 6 with rows c. Rows c were 

 planted with tubers showing only traces of the disease. Rows a 

 yielded at the rate of one hundred sixty-nine bushels per acre; 

 rows 6 yielded at the rate of one hundred eighty bushels per 

 acre, while rows e yield at the rate of two hundred six bushels 

 per acre. 



It should be observed that in each couplet of rows the combined 

 length of a and 6 is equal to the length of c; viz., 188 feet; but 

 only in one case (rows 9 and 10) does the combined yield of ft 

 and 6 equal the yield of c. This is a very significant fact. 



