PESTS OF THE HOP CROP. 155 



accomplished, but until it is effected, washes and appli- 

 cations of powders will be uncertain in their action. 



To the following may be added Whitehead's sum- 

 mary: The action of sulphur is materially influenced 

 by conditions of weather. It is more powerful in heat, 

 when volatilization takes place, and appears to be in- 

 operative in dull, cold seasons. It should always be 

 put on the plants in sunny, still weather, if possible, 

 and as soon as they have got well over the poles. 

 Another sulphuring should be given in about three 

 weeks, and a third later on, especially if there are any 

 traces of mildew upon the "burr." Should the fungus 

 attack the cones when developing or when they are 

 out, sulphur must be used again, though, if possible, 

 this should be avoided, as brewers object sometimes 

 to hops that have been sulphured when fully out. The 

 quantity of sulphur applied for mildew varies from 40 

 to 60 pounds per acre, according to its lightness and 

 quality. In France, very small quantities are put on 

 at a time, with hand bellows, or soufflets. Sulphate of 

 copper solutions have been tried by a few hop planters 

 for mildew, but as yet no definite conclusions have 

 been reached. 



A hop blight more or less common in America, but not 

 injurious is Cylindrosporium hnmuli, E & E. A prominent 

 leaf spot on the hop is Phyllosticta humuli, S. & S. Halstead 

 has found an anthracnose of the genus Cotetotrichum, which 

 causes blotches in the leaves, that turn white and fall away, 

 leaving the foliage full of holes. In Oregon, the hop root 

 bruised is apt to develop n fungus growth called "black 

 knot." If cut off promptly it does no material damage, but 

 if allowed to grow will cause the root to die in a couple of 

 years. 



OTHER PESTS 



Late frosts in spring may be partly guarded against 

 by hilling up the young vines. Early frosts in fall may 

 .be mitigated by spraying with cold water, or by thick 

 clouds of smoke from bonfires when frost threatens. 



Hail, wind and flood often do much damage. If 



