32 Potato Disease and Allied Diseases [cH. 
Baryanum. This fungus is capable of living for a time 
on the decaying matter in soils; on reaching a plant 
its mycelium bores into the cells and soon kills them. 
The stem is thus weakened at the ground level and 
topples over. The non-septate! mycelium of the 
fungus may be found between the cells of a diseased 
seedling. After a time the tips of some of the hyphae 
become round and swollen and are cut off by cross 
walls. These round bodies are the conidia. Placed in 
a hanging drop they give rise to zoospores, like those 
of the potato disease fungus, which germinate and 
produce a mycelium like that on which they were 
borne. The area of the patches in which plants damp 
off increases through the spread of these zoospores or 
of the mycelium along the soil. Unlike the potato 
disease, but like the majority of fungi, this fungus 
produces as the result of fertilization another kind of 
spore which is thick walled and capable of resisting 
adverse conditions for some time. These are known 
as winter spores, and as they remain in the soil through 
the winter, seed beds which are attacked one season 
are very liable to be attacked during the following 
season unless the soil is treated and the spores killed. 
Remedial Measures. 
The conditions which favour the fungus are warmth, 
moisture, and shade. If possible we must try and get 
rid of these by avoiding shady spots for seed beds, and 
also by using soil which allows water to pass through 
freely. 
1 In a non-septate mycelium the hyphae have no cross walls. 
