INJURIES INDUCED BY PLANTS 141 



Black pycnidia, with gonidia similar to those of Fusidium, 

 develop at the base of the dying leaves, and on the wounds that 

 result from the separation of the leaf-fascicles. 



Dr. Brunchorst has not yet been able to observe perithecia, 

 nor has he hitherto succeeded with infection-experiments. Not 

 only has the death of single pines been noticed, but in many 

 cases, especially in Norway, the destruction of large woods has 

 been recorded. 



It is strongly to be insisted upon that whenever this disease 

 appears in young woods of the Austrian pine, all diseased shoots 

 should be cut off and burned. 



SEPTOGLCEUM HARTIGIANUM SACC x 



In the neighbourhood of Munich the branches of the English 

 maple (Acer campestre) suffer from a disease which kills them 

 off before the young shoots develop in spring. In the middle 

 and lower parts of the crown especially, it frequently happens 

 that more than half of the previous year's shoots perish. On 

 these it will be found that the periderm has been ruptured 

 by oblong cushion-like fungus-bodies. 



The disease almost always confines itself to the youngest 

 shoots, the two-year-old shoots being infected only in very 

 exceptional cases. Infection takes place in May and the 

 beginning of June, when the young shoots are still tender and 

 unprovided with periderm. When the spores of the parasite 

 (Fig. 80, 6) come into contact with a young shoot, they germinate 

 within a few hours. The spore represented in the figure had lain 

 in water for five hours only, at the end of which time it showed 

 large germ-tubes at both ends. The mycelium bores into the 

 cortex, and takes possession of the shoot for a distance of 2 4 

 inches, but does not kill it in the same year. Even when the 

 leaves are shed in autumn there are no external symptoms of 

 disease. In spring, the buds of the diseased shoots swell up, 

 as a rule, but soon wither. At that time the mycelium is to be 

 found growing vigorously, not only in the diseased cortex, but 

 also in the medullary rays and the vessels of the wood. It 

 grows both intercellular and intracellular, and pushes numerous 



1 R. Hartig, ForstL Naturwiss.^ Zeitschrift, August 1892. 



