40 Diseases of Greenhouse Crops 



A New Method of Steam Sterilization for 

 Controlling Nematodes* 



It has been our common experience, when at- 

 tempting to control nematodes by steam steriliza- 

 tion of the soil, that very frequently one is unable 

 to secure sufficient steam pressure satisfactorily to 

 use the common harrow-type of sterilizer, the in- 

 verted pan or any modification of these types. 

 When the steam pressure is only 50 to 60 pounds 

 or less at the boiler, and where it becomes necessary 

 to carry this a considerable distance in the green- 

 house, condensation takes place, and as a result 

 these sterilizers cause puddling of the soil and other- 

 wise inefficient work. In our experiments, all modi- 

 fied types of steam sterilizers which originated from 

 those already mentioned were equally unsatisfac- 

 tory; therefore, a method which could utilize a low 

 steam pressure and still do good work without in- 

 jury to the soil, seemed urgent. 



The method to be described herewith was used 

 in a span of fifteen greenhouses, which had the soil 

 badly infected with nematodes. For two successive 

 seasons previous to the treatment of the soil, the 

 entire crops of tomatoes and cucumbers were a total 

 loss. After unsuccessfully trying out all styles of 

 steam sterilizers, the device herein described was de- 

 vised and proved successful. 



It should be remembered where 80 pounds or 



*By L. E. Melchers, Kansas State Agricultural Experiment 

 Station. 



