i8 



A Conifer Disease. 



infection the terminal portions of the shoots and the leaves were 

 covered with the fruit of the fungus. 



A series of experiments proved that the young tender shoots 

 of old trees, as was to be expected, are quite as susceptible to 

 the disease as the shoots of seedlings. The young shoots of 

 old trees growing on branches near to the ground and some- 

 what shaded, became infected by simply placing spores of the 

 Botrytis on the damp young leaves, just as they might be 

 deposited by wind, insects, birds, &c. This method of unpro- 

 tected inoculation never succeeded when tried on shoots high up 

 on the tree and fully exposed to light and air. On the other 

 hand, when inoculated shoots growing high up on the tree were 

 protected for twenty-four hours by oiled paper, infection occurred 

 as usual, and the disease ran its course. These experiments 

 prove that infection can only take place on a large scale near to 

 the giound, where the requisite amount of moisture is most con- 

 stantly present, and where the spores of the fungus are also most 

 abundant, as Botrytis grows indiscriminately on all kinds of 

 fading and dead forms of plant life, fragments of straw from 

 manure, &c. 



Leaves and shoots attacked by the disease eventually fall to 

 the ground, where they remain until the following spring ; the 

 mycelium of the fungus present in the tissues having in the 

 meantime given origin to numerous minute black sclerotia or 

 compact masses of mycelium, which are more or less buried in 

 the dead tissues. Just at the time when the young pine leaves 

 are appearing, these sclerotia produce myriads of spores, which 

 are distributed by various agents, and infection of the leaves 

 results. 



During the past year a number of diseased larch seedlings, 

 sent from a nursery in the North of England to Kew, showed a 

 very unusual condition of the disease under consideration. The 

 terminal shoots were perfectly free from disease, but the lower 

 part of the stem, from the ground-line for two or three inches 

 upwards, was covered with dense tufts of Botrytis (Fig. 2). Many 

 of the seedlings were quite dead and the remainder very nearly 

 so, the leaves having become yellow and shrivelled. 



Microscopic examination showed the cortex to be thoroughly 

 permeated with the mycelium of the fungus, which here and 



