SEVENTH ANNUAL YEAR BOOK-PART V. 193 



COST OF EXTERMINATING WEEDS INTRODUCED IN BAD SEEDS. 



It will cost the farmers of the State a good many thousand dollars to 

 exterminate the Canada thistle, quack grass and rib-plantain introduced 

 carelessly with impure seeds. It has been estimated that it will cost 

 from ten to fifteen dollars per acre to remove these weeds from the farms 

 of Iowa. The financial loss, therefore, to the farmers of the State will be 

 enormous. Can we afford to introduce these weeds with impure seeds? 

 It has been estimated that samples of clover seed containing 1 per cent 

 of weed seeds as impurities contain about one thousand weed seeds per 

 pound. That in another case where the per cent was 2%, the number 

 was 27,600 weed seeds per pound. Mr. Pieters says: "If fifteen pounds 

 were sown per acre, the farmer plants about 414,000 seeds of weeds, 

 which have an equal chance with the crops in which they grow." From 

 our investigation, we may cite what was found in one sample of red 

 clover. The percentage of impurities was as follows: Canada thistle, 

 .707; bull thistle, 1.04; timothy, 1.267; field sorrel, .75; curled dock, 2.05; 

 yellow foxtail, 3.704; green foxtail, 1.25; other weeds, 2.02. The farmer 

 who sent this sample of clover seed would have thoroughly sown his field 

 of ten acres with Canada thistle at the rate of 10,000 plants per acre, 

 15,000 bull thistle, and 30,000 common curled dock; in addition, foxtail 

 and other weed seeds to the amount of 2,000,000 per acre. It would have 

 kept the farmer busy for three years exterminating these bad weeds. We 

 advised the farmer not to sow this seed. The farmers of the county in 

 which this seed was offered for sale refused to buy the same. In some 

 Iowa grown clover seed, some years ago, Mr. Stewart, in the writer's 

 laboratory, found impurities to the amount of 3 to 67 per cent weed seed. 

 Fortunately, most of these impurities were weeds which were common to 

 Iowa. 



IMPURITIES IN CLOVER SEED. 



Rib-grass was found seven times. The Canada thistle and common 

 dodder did not occur in the Iowa grass seed. In our own recent investiga- 

 tion, out of 238 samples of red clover seed examined, 155 samples con- 

 tained timothy, 137 contained dirt and sand, 128 yellow foxtail, 125 con- 

 tained green foxtail. 111 Rugel's plaintain, 105 crab or quack grass, 61 

 rough pig-weed, 44 lamb's quarter, 35 bracted plantain, 27 old witch grass, 

 27 dooryard plantain, 21 Canada thistle, 20 barnyard grass, 20 cockle, 20 

 smooth crab-grass, 15 bull thistle, 10 dodder, 7 wild carrot, 7 starry com- 

 pion, 4 blue vervain, 4 hoary vervain, 4 spurge, 3 English charlock, 3 pep- 

 pergrass, 3 ragweed, 2 cowherd, 2 black bindweed, 1 chickory, 1 couch 

 grass, 1 water hemp, 1 yellow trefoil. 



PER CENT OF IMPURITIES. 



The percentage of impurities of these 238 samples varied greatly. In 

 a. few cases there were no impurities, but in other cases the impurities 

 amounted to 18.606 per cent. The average for red clover was 1.93 per 

 cent. The sample of alfalfa showed a better state of affairs. The highest 

 was 2.417 per cent, with an average impurity of .838 per cent. Alsike 

 13 



