152 THE HOP. 



been carried out. Possibly lime might help to destroy 

 the spore cases. 



2. Certain varieties of hops seem to be specially 

 liable to suffer from this trouble, but apart from possi- 

 ble inherent differences in the plants, more careful 

 manuring should be adopted in order to produce a 

 healthy growth. Excessive amounts of nitrogenous 

 manures make the leaves more readily attackable by 

 mold. Anything which reduces the vitality of the hop 

 — such as cold and damp nights, long continued 

 drouth, or wet weather and want of proper amount of 

 sunshine and fresh air — rindirectly aids mold in its rav- 

 ages. It is generally in ''housed-in" parts where the 

 air is still and damp and wdiere light does not easily 

 penetrate that the worst effects are seen. Systems of 

 training hops should aim at reducing these drawbacks 

 to a minimum. Early training of the lower part of the 

 bine diminishes the likelihood of attack from the soil 

 and also allows of better air circulation. 



3. The hop-mold fungus not only lives upon 

 hops, but also upon many wild plants — groundsel, dan- 

 delion, strawberry, avens, meadow sweet, and many 

 others. There is little doubt that it is from such 

 sources outside the yard that many attacks of mold 

 are begun. 



4. The fungus lives and develops almost entirely 

 upon the outside of the leaf, and on this account it 

 would appear more easy to deal with it by means of 

 washes and external applications of powdered sub- 

 stances that those cases like the potato disease, where 

 the growth of the fungus goes on chiefly inside the 

 leaf. The application by hand or bellows or by spe- 

 cially constructed sulphurators of finely powdered sul- 

 phur to the affected leaf is a remedy for mildews of 

 various kinds, which has been employed for about half 

 a century. 



Mechanically powdered sulphur — roll brimstone 



