254 ELEMENTS OF AGRICULTURE 



Oat smut is carried by the seed and may be controlled 

 in the same manner, using one pint of formalin to fifty 

 gallons of water. The oats are sprinkled with this solu- 

 tion until they are moist enough to nearly pack in the hand. 

 Shovel into a pile, cover and leave two hours. Spread out to 

 dry before sowing. Or they may be dipped in the solution. 



Wheat smut cannot be controlled in this way, because 

 the disease is inside the seed. Corn smut cannot be con- 

 trolled, because the disease lives over winter in the fields 

 and is blown about by the wind. The various rusts of the 

 grain plants cannot be controlled. 



The blight of potatoes may be controlled if the plants 

 are kept coated with Bordeaux mixture, to prevent the 

 entrance of the fungus. About five sprayings are commonly 

 given. In rainy seasons it sometimes pays to give* more. 



Parasitic Flowering Plants 



Relatively few flowering plants live as parasites upon 

 other plants. Perhaps the most common and destructive 

 of these are the dodders, which live on many wild plants 

 and on some of our cultivated ones, such as clover, alfalfa, 

 etc. The dodder stems are long yellow strands with no 

 leaves, growing in mats over their host plants. They twine 

 about the host and send haustoria or suckers into their 

 stems, from which they secure water and food substances. 



Dodder seeds are usually small and are carried with 

 the alfalfa and clover seeds. The best way to control the 

 parasite is to secure seed from a field that does not contain 

 dodder. The seeds of some species, of dodder may be separ- 

 ated out by sieves. 



