Drupaceous Fruits 87 



Excision should be practiced. Spraying lessens the disease 

 but is not wholly effective. 



Coryneum-blight '^^' ^'^ {Coryneum heijennckii Oud.). ^ 

 First noted by Pierce and fully descriljed by Smith, Cory- 

 neum-blight, troublesome in California for years, has been 

 observed as far east as New York, also in Europe and Aus- 

 tralia. 



The symptoms are djdng of the buds of fruiting wood, 

 spotting of green twigs, and dropping or underdevelopment 

 of young leaves antl fruit, accompanied l)y gimimy exudate, 

 especially upon the one-year-old fruiting twigs. Leaves 

 opening from buds which survive the disease are marked by 

 small dead areas of tissue, which soon fall out, leaving "shot 

 holes." It is essentially a winter or early spring disease of 

 fruiting twigs and one-year-old wood, and the principal dam- 

 age is from death of buds and twigs before the fruit de- 

 velops. Infection occurs in winter before new growth begins. 



Pruning, followed by spraying with Bordeaux mixture or 

 other dormant sprays, during the early winter (in California 

 between November 1 and December 15), produces best 

 results. 



• Crown-gall and Hairy-root ^*' ^°-' """ (Pseudomonas tume- 

 faciens EFS.). — Crown-gall causes a tumor-like outgrowth 

 near the ground line on certain trees and shrubs (Fig. 44), 

 particularly upon members of the rose family, pomes, drupes, 

 raspberries, etc. Hairy-root consists of a profuse develop- 

 ment of small tufts of fine roots. 



Careful cross inoculations by Hedgcock, using fragments 

 of galls, have demonstrated that crown-gall of the almond, 

 apricot, blackberry, cherry, peach, plum, prune, chestnut, 

 and walnut are intercommunicable. It has also been demon- 

 strated by Smith and Townsend that crown-gall of the peach 

 tree as well as of tomato, potato, tobacco, beet, hop, carna- 

 tion, grape, raspberry, and apple can be produced by inocula- 

 tion with Pseudomonas tumefaciens, also that the organisms 

 of the peach, apple, hop, rose, and chestnut galls are inter- 

 changeable. 



