594 [ DISEASES OF THE VINE. 



and separates from the wood, which dies and becomes 

 black and rotten. Diseased vines should be uprooted 

 and burned, and the soil allowed to rest for some years 

 before replanting. 



DISEASES CAUSED BY ANIMAL PESTS. 



The eel-worm, Heterodera rad'icicola Mull., a nema- 

 tode worm belonging to the Anguillulidae, attacks the 

 roots of the vine especially in badly drained lands, caus- 

 ing the formation of small roundish galls on the rootlets, 

 within which the eel-worm is coiled. A serious attack of 

 eel-worm in spring may simulate an attack of Phylloxera 

 but the root galls of the latter are distinctly curved or 

 hooked, and at the same time an attack of eel-worm is 

 hardly ever directly fatal. 



7 etranychus telarius, L., a "red-spider" belonging 

 to the Acarinae, attacks the foliage sucking its juices, 

 and causing the formation of roundish spots of dry tissue 

 chiefly on the under surface, which may be so numerous 

 as to coalesce, and cover the whole leaf. Another minute 

 arthropod belonging to the same order is Phytopt^ls 

 Vitis, Land., which is the cause of erinosis or phytoptosis 

 of the vine. This well known disease of the foliage is 

 met with at all stages of active vegetation, being present 

 on quite tender leaves, as well as on the foliage which is 

 about to drop off in autumn, and is shown by characteris- 

 tic blisters of variable size on t u e upper surface, while 

 the corresponding pare of the under surface there is a 

 thick production of felt-like silvery hairs, which after- 

 wards become yellowish red or brown. Against these 

 parasites it is recjomrneded to collect and burn all dry 

 foliage in winter and spring. 



Acridtum migratorium. L., the common locust, A. 

 coerulescens, L., the blue winged locust, A.femur-ruhrum, 

 L , the red-legged locust, are three species whose larvae 



