FRUITS 239 



pecially if the weather is damp and showery when 

 the grapes are ripening. 



Root rot is an obscure trouble which has not been 

 sufficiently studied, and its real cause is not under- 

 stood. A whitening of the layers between the 

 outer and inner bark is always noticeable, and the 

 small roots gradually die and rot ; but so far it has 

 not been possible to connect the disease with any 

 specific fungus. It occurs in all parts of the South, 

 especially in the dry hill lands, and has been tlie 

 cause of the early death of a great number of vine- 

 yards. The 7'otundifoUa grapes seem to be entirely 

 immune to this disease. The Bourquineana varieties, 

 while not fully immune, show a pronounced power 

 of resistance, while- all the other classes are about 

 equally susceptible. It is probable that grafting 

 these other kinds on some strong-growing, resistant 

 kind like the Herbemont would do much to obviate 

 this trouble and to prolong the life of Southern vine- 

 yards. The Delaware, although a slow grower and 

 usually considered delicate, has a pronounced power 

 of resistance, and in many parts of the South it will 

 continue to live and bear crops long after the Con- 

 cord, Ives, and other strong-growing kinds have been 

 entirely destroyed. 



The Phylloxera is a plant louse that occurs in two 

 forms: one causing small galls on the leaves, and the 

 other living on and causing distortions of the roots. 

 It is the root form that does most damage and causes 

 the death of susceptible kinds. It is a native Ameri- 

 can insect, and all the American species of grapes 

 have developed a greater or less immunity to it ; so 



