A PRACTICAL METHOD OF PREVENTING THE DAMPING 

 OFF OF CONIFEROUS SEEDLINGS 



By Ct]as. a. Scott 

 Department of Forestry, Kansas State Experiment Station 



A practical method of sterilizing forest nursery seedbeds with high 

 pressure steam to reduce the loss of evergreen seedlings by damping 

 off, has been recently developed at the Kansas State Experiment Station. 

 The investigations have been prosecuted through two seasons of 

 weather conditions very favorable for the development of the damping 

 off fungus, and the efficiency of the treatment has been given a 

 thorough test. The results have been highly satisfactory from every 

 standpoint. 



Sterilizing the beds reduced the loss from damping oft' to an 

 insignificant degree, excepting in the Engelmann spruce beds, while 

 the seedlings of all the species in the unsterilized beds were nearly an 

 entire loss. 



Germination was secured two to four days earlier in the sterilized 

 beds than in the untreated beds, and a larger percentage of the seeds 

 germinated in the sterilized beds. In a large nursery this would 

 amount to a big item in the purchase of seed. 



Sterilizing the seedbeds destroyed all of the weed seeds and elimi- 

 nated the cost of weeding. This saving equalled the cost of sterilizing 

 the beds. 



The seedlings in the sterilized beds made a more vigorous growth 

 than the seedlings growing in the untreated beds, and at the close of 

 the first season were from two to four times larger than seedlings of 

 the same species grown in the untreated beds. 



METHOD OF TREATMENT 



The seedbeds in the Kansas State Forest Nursery are 4 by 16 feet 

 and spaced uniformily. The steaming pan is 4' 4" by 16' 4" by 6" 

 made of No. 11 gauge boiler iron. The seedbed soil was worked over 

 and thoroughly pulverized to a depth of 8 inches a few days before 

 the beds were sterilized and they were spaded and thoroughly worked 

 over immediately before they were steamed. 



The steaming pan was set over the bed in an inverted position, the 



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