DISEASES OF PLANTS. 551 



in a year or two the entire bush is destroyed. When a branch bearing Botrytis 

 couidiupLores is cut transversely a characteristic discoloration of the wood is 

 seen in which the entire wood cylinder with the exception of a narrow peripheral 

 zone of light color is stained a dark gray. Longitudinal sections of the diseasevl 

 branch show well marked hyphse of Botrytis, ramifying abundantly in pith, wood, 

 and bast, especially in the vessels and medullary rays. The presence of this fungus 

 in considerable quantities in the vessels checks tlie transpiration current and 

 thus causes the sudden wilting of the foliage, while its presence in the pith 

 mftkes its progress either upward or downward easy and rapid. Sclerotia of 

 Bi^cincrca were developed from the diseased wood. The young mycelium of 

 R^cincrai when introduced into a slit in a healthy branch produced the cliarac- 

 teristic wilting of the foliage, and later the conidiophores of the fungus apiK^ared 

 on the inoculated branches. It is claimed that the fungus probably enters 

 through wounds caused by aphids on the tips of the shoots and travels down- 

 ward; also that injuries due to spring frosts may permit the entrance of the 

 fungus. 



In the disease presumably caused by C. ribis the external symptoms are very 

 similar to those of the Botrytis disease, but the wilting usually occurs in the 

 spring just as the young leaves are unfolding, and bushes killed during the 

 winter by this disease have a thin growth of white mycelium on the bark at 

 the base of the dead bush or branch. An old scar or unhealed wound was 

 always found near the base of dead branches or bushes. A cross section of the 

 stem at this point showed a brown discoloration of the wood, except a sector 

 shaped area where its normal light color was unchanged. At the junction be- 

 tween the healthy and diseased wood is a narrow, dark line. The bark also is 

 discolored over a larger area of the stem than the infected wood. The discolored 

 wood extends slightly above and below the wound, and usually both the roots 

 and the upper parts of tlie stems in recently killed bushes are apparently 

 healthy. Microscopic sections of the discolored wood show that it is permeated 

 in all directions by fine branching fungus hyphae, noticeably accompanied by a 

 quantity of yellowish brown substance, wound gum, which partially fills up the 

 vessels and occurs plentifully in the wood parenchyma and medullary rays. 

 These hyphse secrete an enzym capable of dissolving lignin, as they were able to 

 bore through lignin tissues, producing a lai'ge amount of delignification. This 

 fungus is a wound parasite, and probably its spread from plant to i)lant is by 

 means of conidia. Since the fungus can live as a saprophyte in dead wood, all 

 gooseberry bushes killed by this disease should be dug up and burned. 



The appearance of the American gooseberry mildew in Belgium, E. 

 Marchal {Ztschr. Pflanzenkrank., 20 (1910), No. J,, pp. 234, 235).— Attention is 

 called to a local outbreak of this disease (SplKvrothrca mors uvw) on plants 

 which were recently imported from a nursery in Holland. The means taken for 

 its immediate and complete eradication are given, and consi.st of spraying with 

 a 0.35 per cent solution of lime sulphur and the cutting and burning of badly 

 diseased branches and canes. In August and September two more applications 

 of this same mixture were given, and in October after the leaves had fallen they 

 were again sprayed with a 0.6 per cent solution of the lime-sulphur mixture. 



A note on the appearance of two epidemic mildews, B. Namyslowski 

 (Ztschr. Pflanzenkrank., 20 (1910), No. J,, pp. 236-238) .—The author discusses 

 the appearance of the American gooseberry mildew (Spwrothcca mors uva-) in 

 various portions of Russia, and claims that as far as Krakau is concerned the 

 fungus was not introduced on imported berries but is found oidy on local stwk. 



The taxonomic position of the oak mildew prevalent in various European 

 countries is discussed. 



