1050 



THE FRUIT INDUSTRY IN NEW YORK STATE 



attack. The spots on the leaves vary in size from a pinhead to 

 a pea. They are round, oblong, or irregular areas with curved 

 or angular margins. The center is somewhat transparent and 

 gray in color, this color being especially noticeable on the upper 



surface. Within the affected area one 



can plainly discern, especially in old 

 leaves, several minute black specks, 

 the fruit bodies of the causal fungus 

 (Fig. 325). 



The disease is caused by the fungus 

 Mycosphaerella seniina, which pro- 

 duces numerous needle-shaped spores 

 in minute fruit bodies, mentioned as 

 occurring in the spots on the leaves. 

 The spores adhering to each other 

 are forced out of the fruit bodies in 

 long, dark-colored, ropelike strands 

 and are disseminated to other leaves 

 by wind or by spattering raindrops. 

 In the presence of moisture the spores 

 germinate and infect the leaf. 

 The fungus winters on the fallen leaves and produces there the 

 winter fruit bodies from which sexual spores are discharged dur- 

 ing the following spring. These are responsible for bringing about 

 the first infection of the year. 



The disease can be largely prevented by the applications given 

 for the control of pear scab. 



FIG. 325. LEAF SPOT ON 

 PEAR 



LEAF BLIGHT 



This disease is general in the Appalachian region and occurs 

 commonly in practically all nursery districts. In New York it 

 is said to be more abundant in the orchards of the Hudson Valley. 

 It may become severe on pears and quinces and is reported to 

 attack hawthorne, apple, and a few other related plants. Most 

 varieties of pears are susceptible, although Duchess and Kieffer 

 are reported to be resistant, and, of varieties in the nursery, the 

 Kieffer, Angouleme, and Flemish Beauty are said to be freest 

 from p.tt--"k 



