272 Diseases of Economic Plants 



cases where formalin can be used, and will therefore not be 

 described further. The directions for the modified hot-water 

 treatment, drawn from Freeman and Johnson, ^-'^ with slight 

 changes, are as follows: 



After the seed has been cleaned by thorough fanning and 

 sifting, it should l)e soaked for from five to seven hours 

 in water at ordinary room temperature, 17° to 22° C. (63° 

 to 72° F.), then placed in small, loose sacks or wire baskets, 

 containing not more than one-half peck each, and drained 

 for a short time. The seed must be treated in small lots 

 in order that all of the grain may quickly and uniformly 

 reach the desired temperature. Two tubs or vats of water 

 should be provided. In one tub (No. 2) the exact tempera- 

 ture required should be maintained. The other tub (No. 1) 

 is used for bringing the grain to the temperature of the 

 treatment, so as not to lower the temperature in tub No. 2. 

 Galvanized iron tubs of 20 to 40 gallons capacity, and 

 kerosene or gasoline double-burner stoves, are convenient. 

 The drained sacks or baskets of seed should be plunged into 

 tub No. 1 for a minute, then transferred to tub No. 2, and 

 kept agitated while immersed at temperatures and for the 

 periods specified below, the temperatures mentioned being 

 maintained as nearly as possible: For barley, 13 minutes 

 at 52° C. (125.6° F.); for wheat, 10 minutes at 54° C. 

 (129.2° F.). In treating barley, if the temperature should 

 rise above 52° C. (125.6° F.), the time of immersion must 

 be reduced to ten minutes at 53° C. (127.4° F.), or five min- 

 utes at 54° C. (129.2° F.). Above 54° C. (129.2° F.) there 

 is no safe margin. If the temperature falls slightly below 

 52° C. (125.6° F.), the time of treatment should be increased 

 in proportion. A temperature lower than 51° C. (123.8° F.) 

 is not effective. In treating wheat, if the temperature should 

 rise above 54° C. (129.2° F.) or fall lielow 52° C. (125.6° F.), 

 the time for immersion must be diminished or increased ac- 

 cordingly. Under no circumstances should a temperature of 

 more than 55° C. (131° F.) be allowed. Temperatures be- 

 low 51° C. (123.8° F.) are ineffective. A reliable thermometer 



