56 



Levi Otto Gratz 



the same amount of water. Again the germination was 100 per cent, 

 but only 35 per cent of the plants came through the soil, the remaining 

 65 per cent exhibiting definite, blackened, dead sprouts that had emerged 

 from the seeds. Of the 35 per cent, all developed wire stem. All the 

 seeds not covered with sand reached the surface of the soil, and only one- 

 third of these damped-off or developed wire stem. 



Per cent of 

 damping-off 



100 



80 



60 



40 



20 







100- 



80 



60 -4 



40 



20- 

 



Sand- cohered 



S'<%_ 



34-Q7n 



Not sand- cohered 



20 



Figure 15. 



90 100 120 140 160 

 Hours after inoculation 



— 1 1 1 1 1 — 



180 200 220 240 260 300 



INCREASE IN RATE OF DAMPING-OFF OF CABBAGE SEEDLINGS IN SOIL 

 COVERED WITH A LAYER OF FINE QUARTZ SAND (TABLE 19) 

 Soil moistures are given as percentages 



