54 Mildews [CH. 
clean crop, as these varieties are so specialized that the 
one attacking any particular cereal will not attack the 
others. 
Remedial Measures. 
The whole of this fungus is on the outside of the 
plant, and consequently we should expect to be able 
to keep it in check by the use of a suitable fungicide. 
In the case of cereals the difficulties of spraying are 
so great that it is not usual to make application of 
this kind. Damp shady places should be avoided if 
possible as they provide conditions favourable to the 
growth and spread of the fungus. 
Hop and Strawberry Mildew (Sphaerotheca humult). 
This mildew or mould as it is often called belongs to 
the ‘true mildews,” and therefore grows on the outside 
of its host. In wet seasons it has been known to do 
a considerable amount of damage. The first symptoms 
of the disease are small light-coloured spots on the 
leaves. In damp weather the white mycelium of the 
fungus soon appears and begins to spread rapidly. It 
also spreads from plant to plant by means of conidia 
very similar to those of Hrysiphe graminis. After a 
time it becomes a greyish colour. In autumn the 
resting stage or spore-cases are formed; these are of 
a dark brown colour. The greatest amount of damage 
is done when the mildew spreads to the cones. The 
reddening of the cones by the spore-cases has given the 
name of “red mould” to this stage. 
The spore-cases are very similar externally to those 
of Erysiphe graminis. Internally they are different as 
they contain only a single spore-sac or ascus, as may 
