TREE DISEASES AND TREATMENT 
177 
which its possible hosts, the trees and shrubs, also belong. 
Its part in romance and sentiment does not begin until 
the twigs reach the drawing room. On its host the mistle¬ 
toe is a parasite, sapping its strength and retarding its 
growth. The damage starts when the mistletoe dies, 
for in the process of decay it leaves a cavity which 
affords a means of entrance for other more harmful dis¬ 
eases. If allowed to flourish, mistletoe becomes a serious 
enemy. It may be controlled by cutting it away com¬ 
pletely and treating the cavity as recommended in previous 
chapters. 
Various fungous diseases attack the foliage of trees 
and these may be the cause of much damage, since it is 
through the agency of green leaves that a plant gets its real 
nourishment, and any reduction in the foliage decreases 
the tree’s food supply. In addition to this definite damage 
the loss of leaves mars the tree’s appearance. If the 
growth persists for a single season only, the damage is not 
important; but if it proceeds unchecked for several years, 
the tree becomes badly weakened and may die. 
Protection against these diseases is largely by means 
of spraying. The effectual materials are spoken of as 
fungicides, the most useful of which are Bordeaux mixture 
and ammoniacal copper carbonate. The former is the 
least injurious to foliage, while likely to discolor buildings. 
The latter is safer near buildings, but needs to be very 
carefully made and applied in order not to injure the 
foliage. 
Bordeaux Mixture. —Bordeaux mixture is composed 
of copper sulphate (bluestone) and quicklime, with a 
certain quantity of water. The amounts of copper sul¬ 
phate and of lime to be used with a given quantity of 
water vary somewhat, according to the kind of trees to be 
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