July 15, 1924 
Depth Distribution of Root-Knot Nematode 
97 
Introduction Garden at Brooksville, 
Fla. Here the upper soil is a fertile 
sandy loam and the subsoil a heavy 
sticky clay. The subsoil very obviously 
limits the spread of the nematodes 
downward. Here, again, extreme vari¬ 
ation from one month to another is 
shown, due no doubt to the actual 
difference in nematode content of the 
different areas sampled. 
soil, considerable infestation occurs to 
the maximum depth sampled. The 
regions of maximum infestation are on 
the whole, near the surface, though 
below the ordinary plow depth. In 
some of the samples, notably those of 
October, 1921, and March, 1922, very 
abundant infestation was present deep 
in the soil. 
0 HW/W2WZ4 4* 6-0# 
Fig. 4.—Depth distribution of root-knot nematodes in sandy soil at Brooksville, Fla., from April 25, 1921, 
to May 5, 1922 
Figure 4 shows the results of an ex¬ 
periment in which sandy soil from vari¬ 
ous depths in a root-knot infested field 
at Brooksville, Fla., was sampled and 
potted, and planted with tomatoes, at 
the Plant Introduction Garden. The 
results in root-knot infestation were 
recorded by estimates of the relative 
numbers of knots present on the roots. 
As in the first year’s samples of sandy 
Experiment No. 4 was conducted in 
a similar manner to and simultaneously 
with experiment No. 3, except that 
Brooksville hammock land soil was 
used. The monthly variations in depth 
of the regions of maximum infestation, 
as shown in Figure 5, are certainly not 
significant, as regards seasons, and are 
obviously due to variations,in the soils 
sampled. This is indicated by com- 
