For purity: Allowing "a" to represent the component being consid- 

 ered and "b" the difference between that percentage and 100, according 

 to the following formula: 



( a X b ) 

 Pure seed tolerance— 0.6 4- ( 0.2 .\ ) 



' ( 100 ) 



a sample of timothy guaranteed 99.20 would have an allowable variation 

 of .75 or could test as high as 99.95 or as low as 98.45 and be "satisfactory." 



For germination: The following tolerances are applicable: 

 Healthy sprouts found by test in each 100 seeds Tolerance 



96 or over 5 



90 or over but less than 96 6 



80 or over but less than 90 7 



70 or over but less than 80 8 



60 or over but less than 70 9 



Less than 60 10 



Therefore, a sample of seed guaranteed 85 % for germination may be as 

 high as 92';^ or as low as 78' < and be "satisfactory 



>> 



For weed seeds: The law requires in the labeling of agricultural 

 seed (1) that the percentage of all weed seeds present shall be shown on 

 the tag, (2) that no primary noxious weed seeds shall be present in the 

 sample, and (3) that secondary noxious weed seeds shall be given by name 

 and approximate number, per ounce in groups (A) and (B) and per pound 

 in groups (C) and (D), when present singly or collectively in excess of — 



(A) One seed or bulblet in each 5 grams of Agrostis species, Poa 

 species, Rhodes grass, Bermuda grass, timothy, orchard grass, fescues 

 (except meadow fescue), alsike and white clover, reed canary grass, Dallis 

 grass, and other agricultural seeds of similar size and weight, or mixtures 

 within this group; 



(B) One seed or bulblet in each 10 grams of ryegrass, meadow fescue, 

 foxtail millet, alfalfa, red clover, sweetclovers, lespedezas, smooth brome. 

 crimson clover, Brassica species, flax, Agropyron species, and other agri- 

 cultural seeds of similar size and weight, or mixtures within this group, 

 or of this group with (A) ; 



(C) One seed or bulblet in each 25 grams of proso, Sudan grass and 

 other agricultural seeds of similar size and weight, or mixtures not 

 specified in (A), (B), or (D) ; 



(D) One seed or bulblet in each 100 grams of wheat, oats, rye, barley, 

 buckwheat, sorghum (except Sudan grass), vetches, and other agricultural 

 seeds of a size and weight similar to or greater than those within this 

 group, or any mixtures within this group. 



Certain tolerances are allowed, however, to provide for variations and 

 unavoidable errors, but only within very narrow limits and for which there 

 is always a standard formula for computation. Examples: (1) Timothy 

 guaranteed only 2 per cent weed seeds will not be condemned if it has a 

 2.59 per cent. (2) No primary noxious weed seeds are allowed, but the 

 presence of two such seeds in 50 grams of timothy would not be considered 

 a violation. (3) Similarly, some slight variation from the minimum re- 

 quirement for labeling secondary noxious weed seeds will be passed as 

 satisfactory. 



9 



