1 68 DISEASES OF CULTIVATED PLANTS 



elongated, and produce the Phoma form of fructification, as 

 on the leaves. The first indication of injury to the fruit 

 consists in the appearance of a small, livid spot on the skin. 

 At this stage the flesh of the grape below the skin is perfectly 

 sound, proving that infection has occurred from without. 

 The livid spot gradually extends, its mycelium passing into 

 the flesh of the berry, which commences to shrivel, and is 

 soon dead. When the berry commences to shrivel, numerous 

 fructifications of the Phoma type stud its surface, the spores 

 from which quickly infect adjoining berries, and as a rule the 

 entire bunch is destroyed. Along with the Phoma, a second 

 type of perithecium is often present in considerable numbers. 

 These perithecia contain myriads of very minute, rod-shaped, 

 hyaline spermatia about 5 x 0-5 /*. These bodies have not 

 been seen to germinate, and probably represent the spermo- 

 gonia and spermatia met with in many other kinds of fungi, 

 and which are supposed to represent the male or fertilising 

 bodies of earlier times when a trichogyne, to which they 

 became attached, was produced by the oogonium or its 

 equivalent. The fact that they just precede the development 

 of the ascigerous fruit supports this view, although they are 

 not considered as of functional value at the present day, but 

 merely survivals, During the winter or early spring, those 

 shrivelled and mummified grapes that have been killed by the 

 conidial condition of the fungus, bear a crop of ascigerous 

 fruit, the asci being produced in the same perithecia that 

 previously contained the Phoma form of fruit. 



Phoma form. Perithecia minute, black, immersed in the 

 matrix, the mouth above protruding and rupturing the 

 epidermis. Conidia broadly elliptical, hyaline, 4-5 X 3-4 ^, 

 sometimes larger, or variable. 



Ascigerous form. Asci narrowly obovate, containing eight 

 hyaline, obliquely elliptical spores, continuous, 12-14 X 6-7 p. 

 Paraphyses absent. 



Reddick and Wilson, who have paid much attention to this 

 disease in the United States, recommend the following line of 

 treatment. The first and most important point is to destroy 

 all the old mummified berries, as it is the ascigerous fruit 

 produced on these that commence the disease in the spring. 

 All such should be removed from the vines that have re- 

 mained hanging, and those lying on the ground should be 

 buried by ploughing or otherwise. Never allow basal shoots 

 to spread out over the ground. Spray thoroughly, first with 



