METHOD OF PREVENTING DAMPING OFF 195 



In thoroughly pulverized soil the temperatures at given depths 

 are practically uniform throughout. If the soil is not physically uni- 

 form the temperature secured will vary considerably, as hard lumps 

 are not readily penetrated. Hence it is necessary to have the soil 

 thoroughly pulverized before treatment is given. 



An equal area in each of these beds was sown to jack pine, Nor- 

 way spruce. Black Hills (Engelmann) spruce, Austrian pine and 

 western yellow pine. An equal amount of seed of each species was 

 sown in each bed. At the end of the growing season, October 5, a 

 full count of all seedlings in each bed gave the average number of 

 seedlings per square foot as follows : 



Number of Seedling per Square Foot. 



Bed No. 2 steamed 45 mijputes . . 

 Bed No. 3 steamed 30 minutes. . 

 Bed No. 4 steamed 15 minutes. . 

 Bed No. 5 not steamed, seed 



covered with sterilized sand. . . 

 Bed No. 6 not steamed, seed 



covered with sand not steriHzed 



The greatest number of seedlings of each species must b.e considered 

 a normal stand. The number of seeds sown per square foot was not, 

 ascertained by count.. An equal quantity of the three species of pines 

 was sown on an equal area, 16 square feet in each bed. One-half the 

 quantity of each of the species of spruce was sown on eight square 

 feet in each bed. As the seed of the jack pine is much smaller than 

 that of the Austrian or western yellow pines, a large number were sown. 

 The seeds of the spruces are much smaller than those of the jack 

 pine. • Probably the number of seeds of the spruce, sown per unit 

 area of seedbed was fully double the number of seed sown of the 

 jack pine. 



The dififerent beds were given the same care and treatment through- 

 out except for the differences mentioned. 



The seed in the unsterilized beds, numbers 5 and 6, were from two 

 to four days slower in germinating than the seeds in the sterilized 

 beds. From the time the seeds germinated the seedlings in the steri- 

 lized beds made a more vigorous and thrifty growth than the seedlings 

 in the unsterilized beds. At the close of the growing season the seed- 

 lings of the three species of pines in the sterilized beds were from two 



