FlKIvD EXPERIAIENTS. 45 



September lo the Irish Cobblers had "turned" and were 

 fallen down. The Green Mountains were still vigorous. The 

 flea beetles were numerous. On September 14 the lower part 

 of the field went down with the frost. On September 15 the 

 Irish Cobblers were all dead and on September 28 they were 

 dug. On October 13 the Green Mountains were harvested. 



THE YIELDS. 



Irish Cobblers. 1070 feet of row yielded 1000 pounds oif 

 tubers. This is at the rate of 15,430 pounds per acre or 257 

 bushels. Compared with other Irish Cobblers, the tubers were 

 almost thee times as large, many weighing two pounds. The 

 average yield of other Cobblers in a formaldehyrle experiment 

 was 220 bushels per acre, and in a general spraying experi- 

 ment Cobblers yielded at the rate of 150 bushels per acre. 



Green Mountains. 11 64 feet of row yielded 1760 pounds of 

 tubers at the rate of 24,968 pounds, or 416 bushels per acre. 

 The average yield of other Green Mountains in a culture ex- 

 periment was 303 bushels per acre. 



CONCLUSIONS. 



That wild mustard if it had been present would have been 

 killed by these three applications of iron sulphate admits of 

 little doubt. 



The effect of the iron sulphate upon the potato tops was 

 quite similar to that of a hard freeze. They recovered in much 

 the same way as frosted vines do. 



That the increased yield was due to the treatment there is 

 little doubt. But it does not follow that similar results would 

 happen in different seasons under other climatic condition'^ 



The temporary checking of a tuber forming plant may have 

 stimulated tuber growth. It is a common belief that too great 

 a development of vine interferes with tuber setting. That the 

 increased yield was fortuitous seems to be the more plausible 

 explanation. The experiment will be repeated on a larger and 

 more thorough scale at Aroostook Farm in 1914. 



The experience indic3,tes that with a field of potatoes badly 

 infested with mustard spraying with sulphate of iron solution 

 may be resorted to with a reasonable expectation that the yield 



