16 



Several blotches may occur on the same fruit, and in the Ozarks 

 during the past season it was not uncommon to find 20 to 50 blotches 

 on a single apple, covering practically the entire surface. The tissues 

 of the invaded area being dwarfed by the action of the fungvis, further 

 growth of the apple results in a cracking of the fruit similar to that pro- 

 duced by the apple scab fungus. The cracks range from one-fourth to 

 1 inch in length and frequently extend almost to the center of the apple. 

 In extreme cases a crack may almost encircle the apple, practically 

 dividing it in half, and one crack may intersect another, forming a 

 cross. Fruits only slightly affected with the disease may go through 

 the season without developing cracks. These are more commonly 

 developed shortly before the fruit matures, though a few may occur 

 earlier in the season. The skin being thus broken, the fruit becomes 



an easy prey to other 

 fungi and soon goes down 

 in decay. As a rule the 

 affected fruit drops pre- 

 maturely, and the un- 

 sprayed Ben Davis trees 

 left as checks in the 

 demonstration blocks at 

 Bentonville, Ark., shed 

 50 per cent of their crop 

 some days before picking 

 time. 



PERIOD OF IISTFECTION. 



Fig. 



-A Maiden Blush apple affected with apple blotch. 

 (Original.) 



Infection does not be- 

 gin to take place until 

 the fruit is nearly half 

 grown. The blotch was 

 first observed on the check trees June 26, and only a few affected 

 fruits could be found on that date. On July 16 a large percentage of 

 the Ben Davis apples was affected, and by the middle of August it 

 was clearly seen that the crop was practically lost. It developed first 

 on fruit on the lower branches and within the shaded portions of the 

 tree, but finally spread to almost the entire crop. 



THE CAUSE. 



Apple blotch appears to be the same disease as that described from 

 Illinois by Clinton « as due to an undescribed fungus, belonging to 

 the genus Phyllosticta. This fungus is under investigation by Messrs. 

 Korer and Scott, of the Bureau of Plant Industry, who expect to 

 report on it at the end of another season. 



o University of Illinois Agric. Exp. Sta. Bui. 69, pp. 190-192, PL B, fig. 1. 

 283 



