274 Diseases of Economic Plants 



Seed treated as indicated may be planted as soon as it is 

 sufficiently dry to run freely through the drills, making al- 

 lowance for the swollen seed. 



The long hot-water treatment or pasteurization consists in 

 subjecting the seed to a temperature of 45° C. (113° F.) for 

 three hours, the permissible range being 44° to 46° C. (1 1 1° to 

 115° F.). The advantages of this method are greater effi- 

 ciency, less danger of killing the seed, and the need of but a 

 single bath. It is difficult, however, to maintain the proper 

 temperature for so long a time. 



These hot-water treatments, though effective against both 

 smuts of wheat and of barley, are used primarily for the loose 

 smuts of barley and wheat, and are generally combined with 

 the seed-plat, see p. 275, and rogueing. Hot-water treat- 

 ments are much simpler and more accurate of application 

 if steam is available for heating purposes. 



Injury to seed by treatment. — The germinating power of 

 treated seed should be tested, and if low, the rate of planting 

 should be correspondingly increased. The formalin treat- 

 ment does but inappreciable injury to sound seed, though 

 cracked seed are injured by chemicals. The softer wheats are 

 more often cracked than the harder varieties, therefore are 

 more liable to injury by chemical treatments. Seed sub- 

 jected to wetting may be injured in germination power if 

 dried too slowly. However, poor stands attributed to seed 

 injury often are really due to the use of too little seed, since 

 the treated, swollen grain feeds more slowly through the drill. 

 The sensitiveness of various seeds ^-'' to treatments is 

 indicated in the following table. shows no injury, tr a trace 

 only, H — 1-+ very serious, 4-+ less serious. It is to be added, 

 however, that some experimenters report injury to wheat from 

 the dry treatment. 



Wheat Rye Oats Barley 



Formalin 



Dip 



Sprinkle 



Dry 



Soaking 1 hour 



