SOIL DISIIiTFECTION WITH HOT WATER. 3 



TREATMENT OK THE SOIL. 



The soil was then placed in standard 4 and 8 inch unglazed earthen 

 pots and in a section of a raised greenhouse bench. Inasmuch as 

 the soil i^ different containers received different treatments, each 

 series of experiments is here considered separately. 



Four-incJi jyots. — The 4-inch pots were treated by immersing them 

 for 2 1, 5, and 10 minutes, respectively, in boiling water at 98° C. 

 (208° F.). Three pots were included in each treatment, and one was 

 left untreated as a check. The soil used was taken from the green- 

 house bench described, but was not further infected by the addition 

 of nematode-infested roots. During the immersion of the pots the 

 water was kept boiling by means of two large Bunsen burners. The 

 check pot was immersed for a short time in cold water. Following 

 the immersion, the pots were removed and the surplus water allowed 

 to drain off. They were then placed on the greenhouse bench, 

 which was covered with a layer of fresh cinders, to reduce the pos- 

 sibility of reinfestation with nematodes, and allowed to dry for five 

 days before planting. 



This experiment was duplicated, using the same sifted soil plus 

 nematode galls of tomato roots. These galls were cut up into small 

 pieces, about one-third inch long, and mixed with the soil in the top 

 half of the pots. 



Eight-inch pots. — The 8-inch pots were filled with the infested soil 

 to within 1 to 1^ inches of the top when well shaken down. Three 

 pots each were then treated by applying 1,000, 2,000, and 3,000 c. c, 

 respectively, of boihng water at 98° C. (208° F.). An additional 

 pot was thoroughly wet down with cold water and left as a check. 

 In the case of the 1,000 c. c. treatment, the boiling water was all 

 applied at one time, but with the larger treatments it was added as 

 rapidly as it penetrated the soil. 



As soon as the respective quantities of water were added, the pots 

 were covered with newspapers to hold in the heat, and the surplus 

 water was allowed to drain off. The pots were then left on the 

 greenhouse bench to dry for five days previous to planting. 



This experiment was also duplicated, using sifted infested soil 

 plus nematode-infested tomato roots cut up and thoroughly mixed 

 with the topsoil in the pots. 



Greenhouse bench. — ^A portion of a greenhouse bench about 3 by 4 

 feet was divided into four sections approximately 18 by 26 inches 

 by means of 1-inch boards which extended to the bottom of the 

 bench and about 2 inches above the surface of the soil, which was 

 about 5 inches deep. The soil was the same as that used for the pot 

 experiments described above, except that it was not sifted and did 

 not receive additional nematode-infested tomato roots. 



