4 BULLETIN 818, U. S. DEPARTMENT OF AGEICULTURE. 



Section 4 received an application of approximately 17,000 c. c. 

 (17 liters) of cold water and acted as a check. To sections 1, 2, and 3 

 were applied, respectively, 8,500, 13,500, and 17,000 c. c. of boiling 

 water, whicli is approximately equivalent to an application of 750, 

 1,000, and 1,500 c. c. per 8-incli pot of soil. In the case o*f section 1 

 the whole quantity was applied at one time; on sections 2 and 3 the 

 hot water was applied in two doses put on a few minutes apart, for 

 the reasons that the soil would not take up the entire volume of 

 water at one time, and, furthermore, the means for heating this 

 quantity at once were not at hand. In the case of section 1 the 

 water applied was sufficient to wet thoroughly aU the soU, and a 

 smaU proportion ran through. In sections 2 and 3 a considerable 

 proportion of water ran through, but it was noted that the first dose 

 compacted the soil to a certain extent, so that the second dose ran 

 through but slowly. To further assist in holding the heat in the soil, 

 the sections were covered with newspapers immediately following 

 the treatment. The bench sections were left for seven days, to allow 

 the soil to dry out sufficiently for planting. 



PLANTING OF SEED. 



In the 4 and 8 inch pot experiments, Stone tomato seeds were sown 

 five days after the treatment, fairly thick, but as uniformly as possible. 

 In the bench sections two rows each of Stone tomatoes and Big 

 Boston lettuce were sown in a similar manner, especial care being 

 taken to make the sowings as uniform as possible in the different 

 sections. 



RESULTS. 



The results from these experiments were recorded in the form of 

 comparative germination counts taken two weeks after planting, and 

 notes made at intervals on the damping-off and nematode infection 

 and on the size and vigor of the plants. All the plants were allowed to 

 grow for about seven weeks, and the experiment was then terminated. 

 All the plants were removed from the pots and benches, and the soil 

 was washed carefully from the roots, especial care being taken to 

 preserve the entire root systems intact. The plants were then 

 examined for nematode galls or injuries due to the attacks of soil 

 fungi, records being made of the number and severity of each. Iso- 

 lations were made to determine the organism responsible for the 

 damping-off and root discolorations found. PytMum debaryanum 

 was found to be the cause of damping-off, while Rhizoctonia species 

 caused stem lesions and root discolorations. All data obtained 

 were supported by photographs taken at various stages during the 

 progress of the experiment to illustrate the important results noted. 

 The details of the results are given in Tables I and II. 



