SOIL DISIlN^FECTION WITH HOT WATER. 7 



to 4 to 5 inches in height, and all were vigorous and healthy in ap- 

 pearance. Differences existing at the end of the experiment in 

 number, size, and general appearance of the plants in pots receiving 

 the different treatments are shown in Plate IT, figure 2. Compare 

 with Plate II, figure 1, which shows sonic of the same pots at a very- 

 early stage in the experiment. 



4. The application of 3,000 c. c. of boiling water per 8-inch pot 

 (180 cubic inches of soil) gave complete control of both nematodes 

 and soil fungi in both sets of pots. Applications of 1,000 c. c. and 

 2,000 c. c. gave partial control of the pathogenes. An average of 

 20 and 13 per cent, respectively, of the plants in these pots showed 

 mild nematode infection, as compared with 83 per cent of nematode 

 infection in the check pots, most of which was severe. In two of 

 the six pots receiving the 2,000 c. c. treatment no Rhizoctonia infec- 

 tion occurred, while plants in the remaining pots showed slight root 

 discolorations. Nearly aU plants, however, which received the 1,000 

 c. c. treatment showed root discolorations. The roots of the plants 

 in the untreated check pots were badly discolored, many being 

 entirely destroyed by the fungous parasites. A comparison of the 

 appearance of the roots from plants grown in treated and untreated 

 soil is shown in Plate III. 



Table II. — Soil-disinfection tests ivith tomato and lettuce plants grown in shallow 

 bench sections, with hot-water treatment, in February and March, 1918. 



[The bench sections were 5 to 6 inches deep and filled with nematode and fungus-infested soil thoroughly 



mixed by sifting.] 







Application of boil- 





















ing water (at 





Results observed 



an Mar. 8, 1918 (end of experiment). 







98^0.). 





































Pvthium 







Kind of plants 

 and bench 



o 







i 



"3 



O 



a 





Nematode infesta- 

 tion of roots. 



and Rhi- 

 zoctonia 

 infection 



Plant notes. 



section No. 



o 





2 



1 













of roots. 













n 



o 





















s: 



+3 



■V 



ofc 



W 















.^ 











a 

 9? 



9 



a* 

 "a 



o 



o 

 1 



ft 



o 





ft 



3 



i 



>, 



a 



a 



•a 



"3 





o 



|ft 



0^ 



1 



to 



Color.' 





CO 



^ 



Z 



< 



ft 



e 



w 



S 



S 



e 



Ph 



^ 



p-l 



H 





Tomato: 



Inches. 



C.c. 





c.c. 



No. 



















In. 





1 



26 by 18... 

 26 by 16... 

 24 by 18... 

 24 by 16... 



8,500 

 13,500 

 17, 000 



1 

 2 



9 



750 

 1,000 

 1,500 



3 

 

 

 15 



108 

 94 



204 

 75 





 

 

 15 











4 



21 



43 

 28 

 10 

 18 



43 

 28 

 14 

 54 



40 

 30 



7 

 72 



66 

 

 3 



75 



61 







14 



100 



6 

 6 



7 

 4 



Hg. 

 Hg. 



2 



3... 



4 checks. . 





Sy.8 



Lettuce: 













1.. 



26 by 18... 

 26 by 16... 

 24 by 18... 

 24 by 16... 



8,500 

 13,500 

 17,000 



1 



2 

 ? 



750 

 1,000 

 1,500 



65 

 5 

 



25 



178 

 197 

 210 

 32 





 

 

 6 



28 

 

 



12 



43 



21 



2 



2 



71 



21 



2 



20 



40 



11 



1 



64 



178 



32 







32 



100 



16 







100 



2i 

 3 

 5 

 2 



Y. 



2 



Hg. 



3 



Hg. 



4 checks. . 





Sg.« 







1 







' Abbreviations used: Hg= Healthy green, Sg= Sickly green, Sy= Stunted yellow. 

 2 Saturated with cold water, spoor stand. < Stand 25 per cent. 



From the details of the bench experiments, which are given in 

 Table II, the results are here briefly stated. ' 



