PESTS OF THE HOP CROP. 



147 



trouble, and that it would prove the best possible remedy 

 to prevent the spread of or damage by the aphides." 



The eelworm disease causes sickly looking bines 

 and curling of the leaf. The trouble is due to a minute 

 eelworm, which slits and injures the delicate rootlets. 

 The accompanying cut (Fig. 75) is from The Journal of 

 the Wye Agricultural College for April, 1895. I shows 

 the leaves, sgialler in size than usual, a under, b upper, 

 surface, showing characteristic curling of edges and 



FIG. 76. THREADS OF HYPHAE OF HOP MOLD (SphCBTOtheca 



castagnei). 



Summer, or active stage, a. Erect hypha, giving rise to chains of spores (conidia). 

 6, Free "spore" (conidium). 



puckering of veins; natural size. II, Cross-section of 

 leaf, enlarged forty times, showing abnormal tissue. 

 Ill, As in II, showing further growth of tissue at side 

 of midrib. IV, Cross-section of root, natural size, and 

 V, lengthwise section, both showing effect of stern- 

 eel worm (Tylcnchus dcvastatrix). VI, Hop rootlet with 

 attached females of eelworm (Hctcrodera schachtii\ 

 almost natural size. VII, Magnified cross-section of 

 rootlet, showing eelworms at work. VIII, a, female 



