286 PLANT DISEASES 



RASPBERRY SPOT 



(Glocosporium venetum, Speg.) 



A widespread disease, first appearing on the young 

 canes under the form of small reddish spots. These con- 

 tinue to increase in size, and frequently run into each 

 other, forming irregular blotches, which become grey in 

 the centre, and bounded by a red margin. The minute 

 spores ooze out from under the cuticle of the central grey 

 spots, and are at first held together by a viscid substance, 

 which becomes dissolved by moisture; the spores are 

 diffused, germinate at once, and spread the disease. 

 Similar diseased spots are also produced on the leaves. 



PREVENTIVE MEANS. The quickly germinating summer- 

 spore form is the only known mode of reproduction, and 

 it is supposed that the mycelium is perennial in the tissues. 

 Young canes are not killed by the disease the first season, 

 but succumb the second season, the fruit remaining small 

 and shrivelled. 



All diseased leaves and canes should be removed, and 

 the canes should be sprayed with a solution of sulphate of 

 iron two pounds dissolved in five gallons of water during 

 the winter before the leaf-buds expand. After the expan- 

 sion of the foliage, dilute Bordeaux mixture has proved 

 beneficial. 



CURRANT LEAF SPOT 



(Gloeosporium ribis, Mont.) 



The leaves of red and black currants and gooseberries 

 are often attacked by this fungus, and when this occurs to 



