1 



UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 818 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Cliief 



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Washington, D.C. 



PROFESSIONAL PAPER 



January 5, 1920 



SOIL DISINFECTION WITH HOT WATER TO CON- 

 TROL THE ROOT-KNOT NEMATODE AND PARA- 

 SITIC SOIL FUNGI. 



By L. P. Byars and W. W. Gilbert, Pathologists, Office of Cotton, Truck, and 

 Forage Crop Disease Investigations. 



CONTENTS. 



Page. 



Objects of the investigations 1 



Experiment Series 1 2 



Method of procedure 2 



Results 4 



Discussion of results 6 



Page. 



Experiment Series II 8 



Method of procedure 8 



Results 9 



Discussion of results 10 



Summary 13 



OBJECTS OF THE INVESTIGATIONS. 



The experiments described in the following pages were undertaken 

 to obtain more accurate data on the effectiveness of hot water as a 

 means of ridding soil of the root-knot nematode (Heterodera radi- 

 cicola) (Greef .) Miiller) and parasitic fungi usually associated with 

 damping-off and other root troubles. 



The great need of a simple, practical method for disinfecting small 

 quantities of soil in which to grow healthy seedlings for home-garden 

 planting has always existed, but because of the great extension of 

 tomato and other club work in recent years, the need has become 

 more pronounced and more apparent. Such a method would also 

 be especially adapted for disinfecting soil in pots and shallow green- 

 house benches. Very successful results have been obtained by one 

 of the writers in killing the root-knot nematode in infested dasheen 

 tubers, to be used for planting purposes, by soaking them in hot 

 water, without appreciably impairing their viability. Furthermore, 

 a method of soil disinfection by hot water has been used with some 

 success in vegetable greenhouses in the Boston district, but no care- 

 ful experiments have been carried out to determine the temperatures 

 required or the quantity of water necessary to control the soil troubles 



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