222 Report of the Botanical Department of the 



the nmisiially long growing season gave the bordeaux an opportu- 

 nitj to exert its full influence. Had frost come on October 1, aa 

 frequently happens, the difference in yield between sprayed and 

 unsprayed rows would have been much smaller ; and had frost come 

 on September 14, when potato fields in many localities in the 

 State were killed, the gain from spraying would probably have 

 been very small. 



Several persons who saw the experiment during October after 

 the contrast had become marked raised the question as to whether 

 the sprayed rows were increasing their yield at that time. They 

 must have been increasing their yield rapidly else they could not 

 have outyielded the unsprayed rows by as much as 93 bu. per 

 acre. 



Apparently, the increased yield of the sprayed rows was due 

 chiefly to the larger average size of the tubers. On the rows 

 sprayed seven times the tubers were quite large — so large, in 

 fact, that some difficulty might have been experienced in selling 

 them at full price in the regular potato market. 



The potatoes were dug by hand and the product of each row 

 sorted and weighed as in previous years. The yield by rows is 

 shown in the following table : 



Table XIX. — Yields in the Experiments at Geneva in 1911. 



Row. 



1. 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 

 10. 

 11. 

 12. 

 13. 

 14. 

 15. 



Treatment. 



Sprayed 3 times. 

 Sprayed 7 times. 



Unsprayed 



Sprayed 3 times. 

 Sprayed 7 times. 



Unsprayed 



Sprayed 3 times. 

 Sprayed 7 times. 



Unsprayed 



Sprayed 3 times. 

 Sprayed 7 times. 



Unspra.ved 



Sprayed 3 times. 

 Sprayed 7 times. 

 Unsprayed 



♦ Rows 290.4 feet long by 3 feet wide, making the area of each row exactly one-fiftieth acre. 



t At the time of the second spraying, Row 15 was sprayed with bordeaux by mistake. Thia 



Erobably explains, in part, why it yielded so much more than the other check rows; but there must 

 ave been, also., 8ome other disturbing factor else it would not have outyielded Row 13 sprayed 

 three times. 



