DISEASES DUE TO FUNGI 71 
by baking will destroy the disease organisms in the 
soil. 
Root Rot of the Carnation.—The first sign of this 
disease is the yellowing of the leaves. Generally the 
entire plant is affected, but in some cases only a shoot 
or two may show the yellowing. Later, when the fungus 
is firmly established in the plant, wilting during intervals 
of intense sunlight may occur. The disease is caused 
by Rhizoctonia solani Kuhn, which confines itself mainly 
to the roots and lower parts of the plant, where a brown 
rot may develop. High temperatures, over-watering, 
excessive feeding, and deep planting favour the disease. 
Control methods are similar to those described on page 60. 
_ Root Rots of the Sweet-pea. Rhizoctonia Root Rot.— 
This is much the same disease as already described for 
the carnation, but it is more serious than in the latter. 
BULB ROTS 
Sclerotium Disease.—This disease, due to Sclerotium 
tuliparum Klebahn, is found on tulip and other bulbs, 
Towards the end of the flowering period the plants assume 
an abnormally unhealthy appearance, and on lifting the 
bulbs small black sclerotia may be seen in the scales, 
and especially on the inner side of the outer ones. 
Affected bulbs become desiccated and finally die 
(Fig. 12). 
The disease has been investigated by J. K. Rams- 
bottom (40). Infected soil may be sterilized by means 
of steam, while a dressing of flowers of sulphur has fre- 
quently proved beneficial. 
Botrytis Rot.—This disease, which shows itself by the 
development of the typical grey Botrytis mould upon the 
leaves and bulb scales (Fig. 13), and the consequent 
rapid decay of the diseased tissue, is largely connected 
with bad cultural conditions. Hot, moist conditions, 
