360 ANNUAL REPORT OF THE OS. Doc. 



to be regarded with suspicion in most years, especially if the eyes 

 are longer than usual and clustered closely around the seed end. 

 Prof. C. L. Fitch, in Iowa Extension Bulletin, No. 20, states, that 

 "Flatness and relative shortness are the result of healthy growth and 

 signs of strength." One exception I have noticed is that in seasons 

 like 1909 and 1912 when a long drouth was followed by plenty of 

 rain after the tubers had reached their usual shape, I have seen all 

 the best hills in a field of tubers longer than the usual variety of 

 type. Where seed selection was not practiced by neighbors the en- 

 largement took the shape of knots or prongs. The poorer hills died 

 earlier and their tubers were of the usual variety type. When these 

 best hills were used as seed the following seasons the shape went back 

 to normal. Prof. Wm. Stuart, of the National Department of Agri- 

 culture, states, that shape is often affected by the nature of the soil 

 and culture methods as well as the season. So for the present we 

 are not warranted in depending too much on any rigid type as a 

 means of selecting the best seed potatoes. Any one making a tuber- 

 unit test will be greatly surprised at the variation between different 

 units although the seed tubers may have been as near exactly alike 

 as it was possible to select from the bin. 



MARKING AND SAVING HILLS WITH LARGE TOPS 



The large tops are often believed to indicate large yield. While 

 this is often advocated and appears at first thought very probable, 

 I have never been able to find any scientific experiment in which seed 

 from hills with large tops was compared with that from hills judged 

 on the basis of yield and appearance of tubers. My own experience 

 in 11 years of seed selection with a total of over 50 varieties is that 

 hills with large tops are seldom the best yielders. Selection on the 

 basis of yield has practically eliminated the extra large tops. Prof. 

 W. A. Orton, one of our best potato disease experts believes that large 

 and late growing tops may be an indication that the plants have been 

 injured by the heat. I have found them in blue-sprout, white-sprout 

 and Irish Cobbler varieties. Usually each hill has a small number 

 of very large potatoes which are coarse, deep-eyed and often hollow. 

 As these are almost unsalable in large cities, this is another objection 

 to saving hills with large tops. 



BLIGHT RESISTANCE 



A few years ago there was demand for blight resistant potatoes. 

 Sometimes these late growing hills were saved on that account. One 

 of the best potato bulletins we have, Ohio No. 218, by Prof. F. H. 

 Ballon, states, that "Experiments coupled with many observations 

 suggest that little is gained by selecting parent hills on the basis of 

 disease resistance of the plants over selecting parent hills because of 

 superior individual yields. It is the actual work done within the 

 hill that should most interest the potato breeder. The later growing 

 hills simply demonstrate that there develops, through natural plant 

 variation these tardy, deliberate, slow-maturing strains which we 

 should not mistake for strains of special disease resistance. At the 

 Vermont Station hundreds of varieties have been tested for blight 

 resistance. Few showed much, and these were commercially useless 

 from other defects in yield, shape, etc. 



