DISEASES OF TREES 



Sclerotinia Vaccinii is parasitic on Vaccinium Vitis Idcza ; 



S. Oxycocci) on V. Oxycoccos ; S. baccarum^ on V. Myrtillus ; 



S. megalospora, on V. uliginosum. 



Of still greater importance, from an agricultural point of 



view, is Peziza ciborioides {Sclero- 

 tinia Trifolioruiri], the clover-can- 

 ker, or the sclerotium disease of the 

 clover. This parasite is interesting 

 from the fact that on clover-plants 

 infested by the mycelium sclerotia 

 from O'l i cm. in size are formed, 

 and these produce ascocarps in the 

 following year in July or August. 



A similar course of development 

 is found in Peziza Sclerotiorum 

 {Sclerotinia Libert iana), which pro- 

 duces the sclerotium disease of the 

 beetroot and carrot. 



The best known is Peziza 

 Fuckeliana, through its gonidium- 

 bearing form Botrytis cinerea* the 

 vine-mould, which finds its way on 

 to various plants in forcing-houses 

 and conservatories, producing a 

 loose grey mycelial covering and 

 killing the twigs. 



For some years a species, Botrytis 

 Douglasii? has proved injurious to 

 the Douglas fir, which is now gener- 

 ally cultivated in Germany. In 

 seed- and plant-beds especially, 

 where infection by lateral contact 

 is such an easy matter, one often 

 notices that the young incompletely 



developed shoots die and become brown. The shoots of the 



1 Botrytis Douglasii n. sp., C. Freiherr v. Tubeuf, Beitrdge zur Kenntniss 

 der Baumkrankheiten. Berlin, Springer, 1888. 



* [Several forms of Botrytis are common and destructive parasites in our 

 green-houses and gardens. ED.] 



FIG. 71. Branch of the Douglas 

 fir, the youngest shoot of which 

 has been killed by B. Dottglasii. 

 The apex of the shoot of the 

 previous year has also been 

 killed. 



