52 



ENGLISH SUMMARY. 



Should not the reports on the purity of seeds indicate expressly the per- 

 centage by weight of weed seeds and the names of those most plentiful in 

 the samples analysed; and what species are to be described as weeds P 



BY 



Pbof. Leion Bussard, 

 Assistant Director, Seed-Testing Station, Paris. 



Three years ago, at the Copenhagen Congress, Director Bruijning, of 

 the Wageningen station, after demanding that the term " grade " should 

 be substituted for " cultural value "or " real value," suggested the 

 following formula : 



^ , Purity X Germinating power ^^ , . , „ 



Grade = tt^tj Percentage of weeds x 3. 



taking as a base the incontrovertible fact that the presence of weeds in 

 a parcel of seeds is more harmful than that of inert matter, because crops 

 become contaminated through their introduction into the soil. 



The result of the discussion on Director Bruijning's proposal showed 

 that most of those present were not in agreement with it. There are, in 

 fact, several objections to be made. 



The co-efficient 3 for weeds is arbitrary. 



In deducting the percentage of weeds from the 

 Purity X Germinating power 

 100 

 this percentage is reckoned twice, coming, as it also does, into the test for 

 purity. 



Harmless and noxious weeds cannot be given the same importance in 

 the calculations. 



The discrepancy between the figures under the old method and under 

 the new grade one, appears excessive when due to the presence of harmless 

 weeds. 



The latter is difficult of comprehension for growers and seedsmen, and 

 might give rise to mistaken interpretations. 



To avoid confusion, stations should keep to the simple formula : 



„ , Puritv X Germinating power 

 Grade = ~- ^ 



Director Bruijning w£is, however, quite jiastified in stating that it is 

 necessary to let the growers and seedsnaen know the quantities and kinds 

 of weeds in the analysed samples. 



What rules are to be applied ? 



If only a few weeds are in the samples it would be easy and useful to 

 enumerate them. If they are numerous it is useless to name them 

 separately, and no notice need be taken of those of which only 1—2 seeds are 

 found. 



The percentage of weed seeds can be determined by taking the total 

 of all kinds when the percentage of each kind is less than • 30 per cent, of 

 small seeds and • 50 per cent, of large seeds, and by taking the separate 

 percentage of each when in excess of these figures. 



An important question with regard to these rules is : What are to be 

 considered as weeds ? 



In our opinion every extraneous plant in a crop is a weed, such as barley 

 among oats, etc. But the term " weeds " can be restricted to meaning 

 only plants of no cultural value, distinguishing between useful and noxious 

 seeds, this being the interpretation we shall adopt, and the most generally 

 admitted one. 



The limits between useful seeds and noxious seeds is not alwaj^ strictly 

 defined, for in the U.S. Seed Importation Act of 1912, forage plants such a^ 

 Medicago lupulina and Anthyllis vulneraria are counted as weeds. 



