348 
cheaper but more effective than a pressure which falls below this, and 
the amount and cross section area of the tile [pipe] is important. The 
cost of heating soil depends upon the equipment employed and cost 
of labour, &c. Probably not far from 100 cubic feet of soil under 
the most favourable conditions can be heated in one hour’s time to 
00° F he minimum amount of heat 
nematodes. Many other greenhouse pests are killed. The 
relating to the sterilisation of soil by steam, are given in Bull. 
o. 55, Hatch Experiment Station, Mass., U.S.A. 
It has been suggested that dressing the soil with rape meal 
destroys eelworms. This may possibly hold in check or kill active 
eelworms, but it will not kill the eggs. 
It is well known that a poor physical condition of the soil not 
only favours the spread of eelworms, but also prevents their 
. . 
destruction, owing to the difficulty of diffusion and permeation of 
the remedial agent applied. 
otassium permanganate, 1 part in 200 parts, kills eelworms, if 
the soil is saturated at intervals of ten days, and does not injure 
growing plants. This again may be used to save a growing crop, 
but as it has no effect on the eggs, it must not be depended upon 
for exterminating the pests. Finally, carbon bisulphide injected 
t 
. 
pes 
into the soil will kill any active eelworms present. 
Heterodera schachtii, Schm.—The sugar beet eelworm differs from 
H, radicicola in not forming galls or knots on the roots of the host- 
plant. e young females only penetrate the peripheral layer of 
the rootlet, and on increasing in size burst through to the surface, 
remaining attached by a narrowed portion only, hence an attacked 
rootlet presents a knotted appearance, figs. 1 and 8, the knots 
being the external distended females and not galls of plant tissue. 
H, schachtii is a serious pest in the sugar beet fields in Germany 
but up to the present, so far as I am aware, has not been recorded 
on sugar beet in this country. Quite recently, however, HZ. schachtii 
has proved destructive to potatoes in Scotland, where the rootlets 
are attacked in a similar manner to the rootlets of sugar beet, 
ig. 8. This discovery is of some importance, as plants belonging 
to Solanaceae, Papaveraceae, Compositae and Umbelliferae respec- 
tively are stated by Voigt to be free from the attacks of this 
st. Potatoes have been recommended for growing on infested 
t-growing land, along with a trap crop of rape, for the double 
purpose of obtaining a crop and reducing the number of eelworms at 
the same time. It certainly would not be wise to follow this course in 
Great Britain. It may be stated that Oospora scabies, a fungus causing 
‘a scab on potato tubers, also attacks sugar beet, which is an addi- 
tional reason why these two crops should not alternate, as O. scabies 
