187 
The Disorders of Apple and Pear Trees. 
“ La Fumagine des Feuilles,” and its life history is graphically detailed 
and illustrated by many figures. M. Dangeard after long investi- 
gations and cultures of the fungus discovered that, at a certain stage, 
cells ( Kystes ) are formed, either solitary, or ranged like beads side by 
side, in which are oily globules or spores, one or two in each cellule. 
These cells are intended to preserve the fungus during the winter, 
and are brought to the ground with the dead leaves, or are formed 
upon them after their fall. In the spring the fungus is propagated 
by these spores released from their cells and carried by the insect to 
the young leaves. 
This fungus is injurious to apple trees because it lives at the 
expense of their leaves, and chokes up the pores so that they cannot 
assimilate food. When the apples are formed the fungus fastens 
upon them, and spoils their appearance, and checks their growth. * 1 
Even when the fruit is in store the fungus continues its progress as 
long as the juices remain. 
A closely allied fungus (Fusicladium pyrinum) injures pear-trees 
and pears in exactly the same way. Its life history also is identical 
with that of Fusicladium dendriticum. Sorauer says that it is more 
dangerous, as it lives not only on the leaves and fruit but also on 
the young twigs. 3 He gives the names of the Winter Nelis, Bonne 
Louise d’Avranches, Esperen’s Bergamotte, Autumn Butter Pear, 
among others, as most liable to this affection. 
This disorder is very common in England, though it is often 
attributed to climatic conditions or to unkindly growth. Pears are 
particularly subject to it, and in some seasons much of the fruit is 
covered with the peculiar specks which disfigure it and spoil it for 
dessert purposes. As a remedy for these fungi M. Dangeard re- 
commends bouillie bordelaise, which should be applied as a preventive 
early in the season, and the application renewed frequently if the 
fungus spreads. Eau celeste , consisting of 2 lb. 6 oz. of sulphate 
of copper and 2 pts. of ammonia to from 22 to 44 gallons of water, 
may also be employed. 
Sucrated bouillie has been found valuable, made by mixing 4 lb. 
6 oz. of lime in 17 gallons of water. 46 oz. of treacle ( melasses de 
commerce ) are dissolved in 8 gallons of water and mixed with the 
lime water. To this 4 lb. 6 oz. of sulphate of copper, dissolved in 2 
gallons of water, is added and the whole well stirred. The 
stickiness of the treacle retains this composition upon the leaves 
and prevents the spores of the fungi from germinating. 
M. Dangeard deals with other minor affections of apple and pear 
trees, such as rust of the leaves, occasioned by species of Gymnospor- 
angium, and the affections of their roots ( Pourridid ), also caused by 
fungi, which there is not space to describe here. 
Charles Whitehead. 
1 Frank in his Pflanzenliranltlieiten, and Sorauer in his Handluch der 
Pjlanzenkrankheitcn, alike hold that the Fusicladium dendriticum attacks both 
the leaves and fruit of apple trees. 
1 Loc. cit. 
