BUD SELECTION 397 
10 per cent. according to Stuart) of weak, diseased or unproductive 
plants are to be found in all unselected varieties. It is equally certain 
that in the vast majority of cases in ordinary field practice these are 
unrecognized and the resultant effect upon yield is unnoted. Even 
though lack of vigor and low yield is entirely due to disease and hill or 
tuber selection does nothing but eliminate these undesirables, it will be 
well worth doing. But other characters, as well as yield and vigor, 
should be kept in mind in attempting to produce an improved strain of 
potatoes. The ideal market tuber is of medium size, round or oblong in 
outline and somewhat flattened. The eye should be shallow. The 
eating quality should not be overlooked, but varieties and tastes differ 
greatly in this respect. In addition to these, adaptability to local 
conditions and disease resistance should receive attention. 
“The selection of a large number of high-yielding hills which are then thrown 
together for mass planting the ensuing year is not likely to result in any marked 
improvement except by the elimination of the diseased or unproductive plants. 
The only certain method of securing a superior strain is to plant each selection 
separately. . . . Every progressive farmer should have his selection plot, 
in which to grow his yearly selections; and, in addition, he should have his in- 
crease plot, where the promising selections may be increased for the field-crop 
planting” (Stuart). 
Certified Seed Potatoes.—The certification of seed potatoes based on 
official inspections during the growing season and after harvesting has 
been adopted in some states. According to Milward the summer in- 
spection considers stand, vigor of vine, specific and non-specific diseases 
and varietal purity; and bin inspection looks after conformity to type, 
diseases, market condition, quality and yield. In view of the increasing 
importance attached to disease in the degeneration of potato varieties 
some such system of inspection and certification should be adopted in 
every state where potatoes are extensively grown. But it must be borne 
in mind that complete protection against failure or loss is by no means 
assured even under a system of seed certification. Stewart has recently 
reported several instances of sudden degeneration of prolific strains, 
at the Cornell University Experiment Station, through the invasion of 
some obscure disease of which there are a number that infest the potato. 
In some cases only the larger tubers in a hill are affected while the smaller 
tubers are apparently healthy. Stewart’s conclusions follow: 
“(1) Neither normal foliage nor high yield is a guaranty of productivity in 
the progeny of the following season. Degeneration may occur quite suddenly. 
(2) It is unsafe to select seed potatoes from fields containing many degenerate 
plants. Even the normal plants from such fields are liable to produce worthless 
progeny. (3) Mosaic threatens to become an important factor in the production 
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