38 Diseases of Economic Plants 



distinct identity was not recognized until 1895. Since then 

 the disease has been observed in the Eastern and South- 

 eastern states, though not in 

 serious form. Its most destructive 

 center, heretofore, has been in the 

 Ozarks of Arkansas and Missouri 

 and in southern Ilhnois, Ohio, and 

 Indiana where a large per cent of 

 the crop is commonly rendered 

 unfit for barreling. One county 

 alone in Arkansas is estimated to 

 have suffered a loss of $950,000 in 

 1906. Owing to its superficial 

 similarity, blotch has been con- 

 founded with scab in some in- 

 stances. The first publication con- 

 cerning the disease appeared in 

 1902, and the first detailed de- 

 scription in 1907. 



Upon fruit the blotches are from 

 5-20 mm. in diameter, dark in 

 color, with an advancing margin 

 of peculiar, irregular, jagged, or 

 fringed appearance. By coales- 

 cence large spots may form, and 

 owing to tension, cracks appear, 

 enlarging to a centimeter in length, 

 or even girdling the fruit, and 

 reaching to the core. In the older 



„ , . . , , , ^ 1 portions of the blotch, minute 



Fig. 14. — Apple blotch on ' -i- i i t^u i i + i, 



twigs. Original. pycmdia develop. These blotches 



mar the appearance of the fruit 

 and injure it as a salable product. 



Upon twigs, spurs, or shoots are produced cankers, which, 

 during the first year, consist of small spots 2-10 mm. in 

 diameter, tan-colored, each bearing several pycnidia. The 

 margins of the spots are sharply limited, and are usually 



