256 



MANUAL OF FRUIT DISEASES 



time. However, the majority die in winter. Occasionally 

 longitudinally ribbed excrescences develop on the trunk or arm 

 of diseased vines. These outgrowths are not fleshy, nor are 

 they hard, and they should not be confused with crown-gall 

 (see page 253) and outgrowths following winter-injury. In- 

 ternal symptoms are characterized by a dry heart-rot of the 



trunks in affected por- 

 tions. 



In June or early July 

 the leaves show a peculiar 

 yellowing, dwarfing and 

 curling. Later, the dis- 

 coloration disappears, al- 

 though the other abnor- 

 malities persist. Such 

 vines, while apparently 

 on the road to recovery, 

 are found to be dead or 

 are considerably weakened 

 the following year. The 

 vines may die during the 

 summer and as a result 

 the leaves wilt. Many 

 vines freeze to death as a 

 result of a weak growth 

 the previous season. 

 On the green shoots, petioles, peduncles and leaf-veins small 

 reddish brown or black spots are produced (Fig. 68). These 

 may be deep, in which case V-shaped slits are noticeable; or 

 they are more superficial, and are so numerous as to coat the 

 affected part for some distance. When these lesions are older, 

 they show either as reddish elevations or as a longitudinal 

 cracking. 

 Berries affected with the dead-arm disease exhibit a rotting 



FIG. 68. Dead-arm on grape-canes. 



