SOIL DISINFECTION WITH HOT WATER. 



13 



Table V. — Soil-disinfcdion tests with tomato plants grown in shallow bench sections, 

 with hot- water treatment, in May and June, 1918. 



[The bench sections were 



filled with nematode and 



fungus infested soil thoroughly mixed by sifting.] 





Application of boil- 

 ing water (at 98° C.)- 



p. 



"o 



Root infection on Juno 13 (end of experiment). 



Plant notes, 

 May 28. 



Bench 



section. 



No 



a* 

 o 



o 



a ^ 



11 



-A 



< 



Nematode. 



Rhizoctonia. 



to 







6 

 M 



■■3 



•6 



1 





11 



F 



Vigor. 



1 



C.C. 

 11,250 

 22,500 

 33,750 



1 

 1 



2 



C.C. 

 937 



1,875 

 2,812 



107 

 66 

 126 

 102 





 

 



2 



8 











3S 



70 



7 



3 



58 



78 

 7 

 3 



98 



73 

 11 

 2 

 96 





 2 

 2 

 2 





 3 



2 

 2 



7n. 

 5 

 4 



4-5 



4 



Healthy. 



2 



Do. 



3 



Do. 



4 check i . . 



(^) 













1 Saturated with cold water. 



2 One plant damped olT. 



Table VI. 



-Record of temperatures in hot-water disinfection tests of soil in 8-inch 

 pots and bench sections. 



[Treatmentswere with boiling water (at 98° C). Two series of time obser\'ations (in minutes) were made, 

 as follows: Series A, time reiiiiired to reach the temperature indicated; series B, time during which soil 

 temperatures remained above the points indicated. Temperatures were ascertained by inserting stand- 

 ard thermometers to a depth of 3 to 4 inches in the center of the pots and at two points in the bench 

 section (No. 3).] 



Observation 



Water ap- 

 phed(c. c). 



d 



o 



p-l 



a? 



Temperatures (° C). 



data. 



50 



55 



60 



64 



66 



70 



72 



75 



76 



77 



78 



79 



80 



81 



82 



83 



Time, series A : 



( 3,000 



1 4,000 

 |33, 750 



f 3,000 



1 4,000 

 |33, 750 



( 1 



\ 2 

 I 3 

 / 1 

 \ 2 



I 1 

 i 2 

 3 

 / 1 

 I 2 







4 



5 



4 



2.5 



5.5 



'&.5 







6 

 6 

 5 

 4 

 6.5 



'"5 



7 



7 



6 



4.5 



7.5 



9 



7.5 



6.5 



5 



8 



6 



10 





























8.5 

 7 

 6 

 9 



9 

 9.' 5 



10 



8 



6.5 

 10 



10.5 



9 



7 

 12.5 

























S-Lnch pots. . 



G 



"3" 



7.5 



"4" 

 9.5 









7.5 



9 















7 









13 



















33 

 28 

 33 

 40 



38.5 





19 

 19 

 23 



27.5 

 25.5 



9 



ie.'s 

 22 

 20 

 10 



5 

 13 































9.5 

 11 

 14 



14 





4 

 7 



10.5 

 8 















57 



65.5 



63.5 



61.5 



48.5 













S-inch pots. . 



G 



16.' 2 

 80.5 



.53" 

 36.5 



41" 5 







9 

 3.5 



6.5 























tionJ 























































1 The application of hot water to the bench section (No. 3) was at the rate of 3,000 c. c. per 8-inch pot ol 

 soil. 



SUMMARY. 



1. The root-knot nematode {Heterodera radicicola), Rhizoctonia 

 species, and PytJiium deharyanum can be eliminated from soil in 

 4-inch pots by submersion for 5 minutes in water at 98° C. (208° F.). 



2. These organisms can also be killed in 8-inch pots by the appli- 

 cation of 3,000 c. c. of water heated to 98° C. (208° F.). This treat- 

 ment is the equivalent of an application of about 7 gallons per cubic 

 foot of soil. 



3. These pathogenes are almost entirely destroyed in 8-inch pots 

 by treatment with 2,000 c. c. of boiling water (5 gallons per cubic 

 foot). 



