270 DISEASES OF CULTIVATED PLANTS 



time considered as an independent plant. The mature 

 conidia have a strong smell, resembling almonds, that proves 

 attractive to flies, who unconsciously convey the spores on to 

 the stigma of the Vaccinium flowers. Such conidia germinate 

 on the stigma, and send their germ-tubes down into the ovary, 

 where they form a sclerotium. Such infected fruits soon 

 become hard and dry and fall to the ground where they 

 remain until the following spring, when they give origin to one 

 or more ascophores. 



Ascophores often solitary, rarely two from a sclerotium, 

 chestnut colour, 5-15 mm. across, stem often crooked, slender, 

 fixed to the ground by rhizoids at the base ; spores 8 in an 

 ascus, elliptic-oblong, of two sizes, the largest 12-15x5-6 /*, 

 the remaining four slightly smaller. Conidia in chains, lemon- 

 shaped, colourless, 31-32 X 19-25 M. 



Sclerotinia heteroica (Wor.). Heteroecism is not confined to 

 the Uredinaceae or rusts, as the present species has been 

 proved by Woronin to be heteroecious. The ascosphores of 

 S. heteroica are dispersed by wind, and those that happen to 

 alight on young leaves of Vaccinium uliginosum cause infec- 

 tion, and within a short time produce the conidial form of the 

 fungus. These spores are in turn deposited by insects or 

 wind on the stigmas of the flowers of Ledum palustre. As a 

 result of this infection a sclerotium is formed in the ovary of 

 Ledum. These sclerotia after lying on the ground throughout 

 the winter, produce ascophores, the spores from which infect 

 Vaccinium leaves. 



Woronin, Mem. Acad. Imp. St. Petersb., Ser. 7, 26, 10 pi. 

 (1888). 



Woronin and Nawaschin, Zeitschr. f. Pflanzenkr.^ 6, p. 129 

 (1896). 



Brown fruit rot. This is undoubtedly the most destructive 

 and widely distributed of fungus parasites attacking fruit of 

 all kinds belonging to the order Rosaceae. The fungus caus- 

 ing all this trouble has been known until quite recently as 

 Monilia fructigena (Pers.), now, however, it has been definitely 

 proved that this same Monilia is only the conidial form of a 

 higher ascigerous fungus, and will henceforth, or for some 

 time at all events, be known as Sclerotinia fructigena (Schrot.). 



The Monilia form does all the injury and is the only stage 

 that has up to the present been met with in this country, or 



