24 



These diseased spots become white and are surrounded with a purplish 

 border. On these dead, white areas may be found in early summer 

 blackish specks which are the fruit-spots of the fungus. When examined 

 carefully each speck is seen to be composed of minute tufts of spore-bearing 

 stalks which arise from a mass of mycelium lying beneath the epidermis. 

 On the rupture of the epidermis the spores are set free and are capable of 

 spreading the disease during the summer. A winter form of spore is also 

 produced in autumn on leaves that have been killed by the fungus. Such 

 spores (ascospores) are borne in sacs enclosed in black perithecia which 

 in turn are embedded mthin the tissues of the leaf. Each perithecium 

 has a projecting mouth or opening through which the spores at maturity 

 escape in the spring. There are several sacs (asci) in each perithecium, 

 and eight two-celled spores in each sac. These winter spores are capable 

 of starting the disease afresh on the new leaves (Fig. 2). 



Treatment — The leaves should be removed and burned after the fruit 

 is picked so as to destroy the winter form of the fungus. The plants should 

 be sprayed twice with Bordeaux, once when the new leaves are appearing 

 and again before the flowers open. Only healthy unspotted plants should 

 be set out. The practice of setting out a new plantation every year 

 prevents the development of the disease. 



