42 



PLANT PKOrAGATION 



If only 10,000,000 seeds are sown to the acre. Sample 1 wouM 

 provide over 20 weed seeds to the square 3'ard, while Sample No. 3 

 would distribute 240. But notice also the number of good seeds ob- 

 tained for a cent and figure out how much is being paid for inferior 

 and weed seeds in each case; then judge the help that pure seed 

 will be in preventing weed growth on the farm. 



The Canadian Department of Agriculture found that "red 

 clover" seed sold in Ontario contained 6,000 to 15,000 weed seeds 

 to the pound and in alsike as high as 23,550 to 49,830. 



An American .sample of alfalfa gave 6.8 per cent or about 



32,500 seeds in a pound of 

 weed seeds, including 5.490 of 

 dodder (see C, 72), one of 

 the worst of weeds, because, 

 being parasitic, it kills all the 

 alfalfa it reaches. 



In certain parts of the 

 United States, it is stated, 

 clover seed tailings are some- 

 times used on the farm, the 

 clean seed being sold. Such 

 tailings have been found to 

 contain over 273,000 weed 

 seeds to the pound. Such 

 seed will soon make any 

 farm a weed paradise. 



72. Losses due to low- 

 grade seeds are evident 

 frf)m the examples cited. 

 The.se may be grouped 

 under the following 

 head.s: A. Direct loss 

 on the purchase. B. 

 Loss of crop due to in- 

 sufficient good seed 

 sown to the acre, with 

 possible total loss in 

 worst cases. C. Loss 

 due to direct destruction 

 of crop because of intro- 

 duced parasites such as 

 dodder and broom rape. 

 FIG. 33-RHizoMEs Y) Neccssary cost of ex- 



1. Iris showing old rhizome at 4eft and + i • .u j 



new at right. 2. Rhubarb rhizome. ^ra Cleaning tnC SCeQ 



