312 



STATE HORTICUL.TUKAL SOCIETY. 



remedy for the last two diseases is to spray, and then see that all diseased 

 fruits are destroyed. 



Were a different treatment required for each of the^ diseases of the 

 quince, one would soon be discouraged, but, as in most other cases, the 

 sprayings recommended for one will suffice for all, and the^labor is after all 

 not burdensome. 



FUNGOUS DISEASES OF THE GRAPE. 

 DOWNY MILDEW OF THE GRAPE {Plasmopara viticola (B. & C), Bed. & De Ton.). 



Fig. 28.— Downy Mildew of the Geape, Plasmopara viticola. 



1. Sectioa of leaf (greatly magnified) shewing conidial stage. 



2. Showing the same, lees magnified. 



3. The same, showing the effect of the fungus, the leaf brown and shriveled. 



4. Germinating conidia. 



5-8. Development of conidia through zoospore and swarm-spore stages. 



9. Spore. 



10. Germinating spore. 

 11-13. Fertilization of oogonium and development of the oospore. 



14. Section of leaf greatly magnified, showing mycelial thread passing between 

 the cells, and sending its hanstoria into them. 



15. Branching myceliam, the spots representing haostoria. — After Viala. 



