EXPERIMENT STATION BULLETINS. 359 



GRADING 



The careful grading of potatoes as to size and quality is essential. Pota- 

 toes of high quality that are carefully graded generally bring a premium over 

 potatoes that are not well graded. There is always a good demand for the 

 best quality stock. 



It is a good plan to grade potatoes over a mechanical sorter before they are 

 placed in storage. This process removes much of the dirt from the potatoes 

 and separates the culls from the marketable stock. The mechanical sorter 

 will grade potatoes as to size, but the task of removing ill-shaped, scabby or 

 mechanically injured potatoes rests with the operator. 



Not only is it important that potatoes be graded, but it is equally as im- 

 portant that the grades be standardized, so that buyers and sellers of potatoes 

 will have a common basis on which to do business. 



The following standard grades are recommended by the U. S. Department 

 of Agriculture. (Department Circular 238, July, 1922.) 



U. S. No. 1 



U. S. No. 1 shall consist of potatoes of similar varietal characteristics which 

 are not badly mis-shapen, which are free from freezing injury and soft rot, 

 and from damage caused by dirt or other foreign matter, sunburn, second 

 growth, growth cracks, hollow-heart, cuts, scab, blight, dry rot, disease 

 insects, or mechanical or other means. 



The diameter of potatoes of round varieties shall not be less than one and 

 seven-eighths inches, and of potatoes of long varieties, one and three-fourths 

 inches. 



In order to allow for variations incident to proper grading and handling, 

 not more than five per cent, by weight, of any lot may be below the pre- 

 scribed size, and, in addition, not more than six per cent, by weight, may 

 be below the remaining requirements of this grade, but not to exceed one- 

 third of this six per cent tolerance shall be allowed for potatoes affected by 

 soft rot. 



V. S. No. 1 Small 



U. S. No. 1 Small shall consist of potatoes ranging in size from one and 

 one-half inches to one and seven-eighths inches in diameter but meeting all 

 the other requirements of U. S. No. 1. 



In order to allow for variations incident to proper grading and handling 

 not more than twenty-five per cent, by weight, of any lot may vary from the 

 prescribed size, but not to exceed one-fifth of this tolerance shall be allowed 

 for potatoes under one and one-half inches in diameter. In addition not more 

 than six per cent, by weight, may be below the remaining requirements of 

 this grade, but not to exceed one-third of this six per cent tolerance shall be 

 allowed for potatoes affected by soft rot. 



U. S. No. 2 



U. S. No. 2 shall consist of potatoes of similar varietal characteristics which 

 are free from freezing injury and soft rot, and from serious damage caused 

 by sunburn, cuts, scab, blight, dry rot, disease, insects, or mechanical or 

 other means. 



