12 



N. H. AGR. EXPERIMENT STATION. 



[Bulletin 157 



Fig. 11.— Chlamydos- 

 pores from a fruit spot. 



seems to check the development of the spots, but in cellar 

 storage they often become more sunken and spread deeper into 

 the tissue of the apple. They become brown and are much 

 enlarged sometimes attaining a diameter of one half inch (Fig. 7). 

 In late stages of the disease numerous 

 minute black elevations appear in the spots, 

 caused by the develop- 

 ment of p3'cnidia be- 

 neath the epidermis. 

 The pycnidia are some- 

 times arranged in the 

 form of a circle. They 

 break through to the 

 surface and set free 

 numerous minute spores 

 (Fig. 10). 



Thick walled spores 

 known as chlamydospores are common in 

 the apple tissue and are probably impor- 

 tant in carrying the disease over the 

 winter (Fig. 11). Another spore that is 

 found in the host tissue and is extremely common in cultures 

 of the fungus is shown in Fig. 12. These spores are produced 



in indefinite numbers from 

 knob-like projections on 

 the side of the fungous 

 threads (Fig. 13). 



Recent experiments^ 

 have shown that the 

 fungus causing the fruit 

 spot of apples is also 

 responsible for a similar 

 spot on quinces known as 

 "quince blotch." The dis- 

 ease may spread from one 

 host to the other. 



Treatment. The fungus 

 does not attack the apples until thej' are nearly grown. Con- 



Fig. 12. — Spores of Phoma 

 Pomi from a fruit spot. 



Fig. 13. — Spore formation of Phoma Pomi in 

 cultures. 



1 Brooks, Charles, and Black, Caroline A. Apple Fruit Spot and Quince Blotch. Phytopath- 

 ology II, 63-73, 1912. 



