196 FUNGOUS DISEASES OF PLANTS 



apparently requires two hosts to complete its development and is, 

 therefore, an instance of what is denoted hetercecism, a condition 

 discussed more at length under the rust fungi. 



Sclerotinia Rhododendri Fischer, 1 like the preceding, appears 

 to be hetercecious in character. It is found on Rhododendron 

 ferrugineum and Rhododendron hirsutum. 



VIII. GRAY MOLD, OR BOTRYTIS DISEASE 

 Sclerotinia Fuckeliana De Bary 



Brooks, F. T. Observations on the Biology of Botrytis cinerea. Ann. Bot. 



22: 479-484. ,figs. 1-4. 1908. 

 Tstvanffi, G. DE. Etudes microbiologiques et mycologiques sur le rot gris de 



la vigne. Ann. d. l'institut central ampel. roy. Hongrois (1905) : 183-360. 

 Kissling, E. Zur Biologie der Botrytis cinerea. Hedwigia 28 : 227-256. 



1889. 

 Nordhausen, M. Beitrage zur Biologie parasitaren Pilze. Jahrb. f. wiss. 



Bot. 33: 1-46. 1898. 

 Smith, R. E. Botrytis and Sclerotinia. Botan. Gaz. 29 : 369-407. pis. 23- 



27- fig s - J ~3- *9°°- 

 Smith, R. E. The Parasitism of Botrytis cinerea. Botan. Gaz. 38: 421-436. 

 1902. 



Occurrence and effects. In the conidial stage this is one of the 

 most common fungi known upon vegetation. It may propagate 

 itself indefinitely as a saprophyte upon fallen or dejected flowers 

 and leaves, or upon decaying organic matter. Again, it may, as 

 a parasite, produce a variety of rots, decays, or stem diseases, 

 especially in greenhouse or other plants grown under moist, 

 warm conditions. 



In Europe it is important as a disease of the leaves and fruit 

 of the grape. While such injuries may be serious, the abundance 

 of this fungus on the fruit, in certain regions, late in the season 

 gives promise of high-class wine production. The grapes are then 

 juicy and rich in sugar. It attacks other woody plants. Smith re- 

 gards the Botrytis Douglasii Tubeuf, 2 reported destructive to 

 young conifers, as synonymous with this species, and he has 

 found it responsible for a disease of the linden {Tiliaparviflora) 

 in the nursery. It seems to be the less frequent cause of lettuce 

 " drop " in the greenhouse. This disease, subsequently discussed 



1 Fischer. Ber. d. schweiz. bot. Ges. 1894. 



2 Tubeuf, K. von. Botan. Centrbl. 33 : 347. 1888. 



