88 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



The present, or a very closely related fungus, does immense 

 injury to lilies, daffodils, snowdrops, and allied plants, and in 

 such cases it is not wise to continue cultivating similar plants in 

 those places where the disease has once appeared, as the sclerotia 

 of the fungus are formed in the soil, and a repetition of the 

 disease is almost certain. 



Pear Leaf Cluster-Cup. (Gymnosporangium Sabincs, Wint.) 



This fungus grows on two different host-plants at different 

 periods of its existence. The spring stage grows on various 

 kinds of juniper, especially Juniperus Sabina, bursting through 

 the bark in April and May under the form of reddish-brown 

 gelatinous masses, quarter to half an inch long. These masses 

 consist of myriads of spores, which germinate without falling 

 away from the sticky masses on which they are formed, and 

 produce a crop of still smaller, secondary spores. These 

 secondary spores are carried in the air by currents, and such as 

 happen to alight on the damp surface of pear leaves commence 

 to germinate at once, and soon enter the tissues of the leaf. 

 About a fortnight after the infection of a leaf, clusters of 

 minute cylindrical bodies burst through the epidermis of the leaf. 

 These little bodies are popularly known as cluster-cups ; the 

 outside cover splits into shreds at the tip, and liberates the 

 minute spores contained in its interior. The spores produced in 

 the cluster-cups, curiously enough, cannot again directly infect 

 pear leaves, but must be conveyed by some agent on to the 

 branch of a juniper, where they germinate, enter the tissues, and 

 in due course give origin to the gelatinous masses already 

 described, the spores of which, in turn, cannot infect the kind 

 of tree on which they are produced, but must find their way on 

 to the surface of young pear leaves. When pear leaves are 

 badly attacked they fall early in the season, thus affecting the 

 existing fruit crop, and also that of the following season, as the 

 wood is not properly matured, and there is a lack of reserve 

 material. It is important to remember that the infected pear 

 leaves will not infect other pear trees, but only juniper trees, 

 and that when the pear leaves have fallen the pear tree is 

 perfectly free from disease ; that is to say, the mycelium of the 

 fungus does not spread from the leaves into the branches. On 



