14 FARMERS' BULLETIN 996. 



the seed in sowing, or by contamination \vith adjoining diseased 

 soil if the bed has not been kept covered after having been sterilized. 

 Diluting material, like punk, can be readily sterilized at the time of 

 steaming the soil by placing it in a bucket inserted under the pan, 

 or it may be kept in the oven of a kitchen stove for several hours at 

 a moderate temperature. 



The seed may be safely sown 12 hours after the steaming of the 

 beds. Dry seeds only should be used. There is a temporary injurious 

 action in the soil after steaming which retards the growth of the 

 young plant for 10 to 14 days and sometimes longer. Sprouted seed 

 is more readily injured by this temporary effect of steaming, but 

 when dry seed is sown the effect has largely disappeared when the 

 first shoots appear. This condition may sometimes retard the develop- 

 ment of the plants appreciably during the first three weeks after sow- 

 ing, but this is followed by a decided stimulating action, so that 

 plants in sterilized beds are usually ready for setting two weeks 

 earlier than plants on unsteamed beds. 



Steamed seed beds require much more water to produce a crop 

 of seedlings than untreated seed beds. The surface soil is inclined 

 to dry or crumble, and because of this tendency it is advisable to 

 locate the seed beds near an easily available water supply. During 

 clear, bright weather the beds should be inspected late in the morn- 

 ing and again in the middle of the afternoon, as the soil is very 

 likely to dry out, killing young seedlings. Because steamed soil re- 

 quires larger quantities of. water the tendency is to overwater. In 

 this, care must be used, especially if the beds are sown rather thickly, 

 since there is danger of the occurrence pf damping-off under certain 

 conditions. It is an advantage to keep the seed beds occupied after 

 the tobacco plants are taken off. Steamed beds are especially 

 adapted for growing late vegetable crops, which practice tends to 

 keep the beds free from weeds. 



THE FORMALDEHYDE METHOD OF STERILIZING SEED BEDS. 



When steam sterilization can not be used, formaldehyde may be 

 employed to control seed-bed diseases. One gallon of commercial 

 40-per-cent formaldehyde solution is diluted in 50 gallons of water. 

 This solution is applied at the rate of 2 quarts per square foot of 

 seed bed, using a common sprinkling can. 



The seed bed should be prepared for sowing, and to do the most 

 effective work the soil should be dry enough to absorb all of the 

 formaldehyde solution. To prevent the washing of the soil, the 

 necessary quantity should be put on in a number of applications at 

 intervals of, say, 20 to 30 minutes. When all the solution is ab- 

 sorbed the bed should be covered with blankets for 24 hours to 



