392 



MANUAL OF FRUIT DISEASES 



and related plants like the juneberry, hawthorn and apple. 

 But in order to complete the life-history it must have the red 

 cedar, or juniper (Juniperus communis and J. virginiana). 

 On the red cedar twigs there are produced peculiar canker-like 



lesions (Fig. 116). These diseased- 

 spots begin their development in 

 midsummer. The fungus hibernates 

 within the twig as mycelium. With 

 the advent of the first warm, moist 

 spring weather the fungus resumes 

 growth and development. On the 

 surface of the affected area numerous 

 yellow, gelatinous masses appear, 

 the teliospores of the fungus. Each 

 teliospore germinates by develop- 

 ing a short tube (promycelium) on 

 which four sporidia are borne. These 

 sporidia are discharged in thousands, 

 carried by the wind, and some of 

 them infect the quince or the related 

 plants already listed. The sporidia 

 never reinfect the cedars. On the 

 quince, the sporidia germinate, form- 

 ing germtubes which grow into the 

 tissues of the fruit and twig, causing 

 the distortions and malformations 

 already described. Finally the tubu- 

 lar projections, which in mass are 

 an orange fringe-like growth, develop 

 another sort of spores, aecio-spores. 

 These are peculiar, like the sporidia 



developed on the cedar, in that they cannot reinfect the 

 quince, but may infect the cedars. About one year is re- 

 quired for the completion of the life-history of this pathogene. 



FIG. 116. Quince-rust on 

 red cedar. 



