APPENDIX 449 



have fared worst in this respect; cherries, peaches, and 

 apricots to a smaller extent. The stem is the part 

 attacked, and the tree almost invariably dies the second 

 season after infection, caused by the complete girdling 

 and destruction of the cambium. The earliest indication 

 of the disease is the presence of very slightly depressed or 

 sunken patches of the bark, which are rough with crowded 

 and very minute brownish points, just visible to the naked 

 eye. These points correspond to the openings of the first 

 or conidial form of fruit of the fungus, from which myriads 

 of exceedingly minute spores escape at maturity; these 

 spores are carried by wind, insects, etc., and in turn infect 

 neighbouring trees. 



During the second spring after infection the patches 

 increase in number, the bark becoming more shrunken, 

 brown, dead, and not easily removed from the wood. A 

 crop of spores is again produced the second season, after 

 which the tree usually dies, unless all the patches of disease 

 happen to be located on one side of the trunk, when the 

 tree may continue to prolong its existence for another year. 



After the tree is quite dead the diseased patches that 

 previously produced the conidial form of fruit now give 

 ongin to a second and higher form of fruit, which is recog- 

 nised by the more scattered and larger pustules or fruit 

 clusters which burst through the bark. 



Preventive Means. — Up to the present all cases of 

 disease observed have occurred where the trees were 

 growing in clay land, and the too common practice of 

 planting too deep in. the ground also favours the disease. 

 The circumstances point to the fact that ample aerati >n 

 of the soil is very important. 



Up to the age of at least ten years the wounds caused 

 2 F 



