1002 
DISEASES OF ORNAMENTAL PLANTS 
Ornamental plants are for the most part 
subject to the same kinds of troubles as 
plants of the same species or family but 
which may have acquired more economic 
importance. Usually a reference to the 
list of diseases of kindred plants found 
in the main body of this work will give 
the reader the information needed for 
recognizing and controlling the diseases 
of ornamentals. A few of the more im- 
portant ones are given in this section in 
alphabetical order with the exception of 
roses which may be found under Rose in 
the Floriculture section. 
Anthracnose 
Maples, oaks, lindens, sycamores and 
other trees are affected by some one of 
the anthracnoses. The leaves of young 
trees and shoots are affected. It may be 
controlled by the use of Bordeaux in the 
nursery and early in the season. 
Reference 
Duggar, Fungus Diseases of Plants. 
Black Spot of Maple 
Rhytsuma acerinum (Pers ) Fr. 
This fungus occurs on maples, willows 
and other forest trees. It appears as an 
irregular black spot upon the leaf Not 
serious. 
Carnation Bud Rot 
Sporatrichum poae Px. 
A serious bud disease which has caused 
severe losses in greenhouses in several 
states. It causes a disfigurement of the 
flowers with eventual rotting of the en- 
tire flower in severe cases. Controlled 
by general sanitation and destruction of 
all diseased specimens by burning. 
Reference 
Duggar, Fungus Diseases of Plants. 
Crown Gall 
Bacterwm tumefaciens 
This disease is common to many spe- 
cies of plants. A full discussion will be 
found under Apple Diseases. 
Decay or Brown Rot of Trees 
Polyporus sulphureus (Bull.) Fr. 
This fungus seems to be universal 
where trees are grown and attacks the 
elm, maple, oak, beech, birch, willow, pop- 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
lar and many, if not most, other shade 
trees including the conifers. 
When the fungus reaches the fruiting 
stage it appears as a bright, sulphur-yel- 
low, sponge-like cluster, very striking in 
appearance. The spores find lodgment 
in wounds, broken limbs and knots and 
the growing fungus thus finds entrance 
to the heart wood, which decays and is 
eventually reduced to a brittle mass 
which may be readily ground to powder. 
Control 
The only practicable method of control 
is by painting wounds made by pruning 
or otherwise with some heavy antiseptic 
paint. 
Reference 
Duggar, Fungus Diseases of Plants, 
Fusarium 
A species of fusarium produces a wilt 
of China asters and a rosette of carna- 
tions. Sterilization of the soil seems the 
only remedy. 
Reference 
Duggar, Fungus Diseases of Plants. 
Leaf Bloteh 
See black spot of maple, this section 
Rhododendron Rust 
Chrysomyza rhododendri (Dec.) DeBary 
This is the most common disease of 
rhododendron and occurs in practically 
all regions where the rhododendron is na- 
tive and particularly where spruce and 
fir abound as the fir is also a host plant. 
No method of control has been worked 
out. 
Powdery Mildew 
See under Apple, Pear, Peach Diseases. 
Root Rot 
several forms of root rot attack carna- 
tions, violets, asters, etc. The trouble is 
most likely to occur in alkaline soils or 
souls poorly drained. Care should be 
taken not to set out plants which are 
already affected and attention to drainage 
and manuring to correct alkaline condi- 
tions will be effective. These rots have 
a wide range of host plants. See under 
potato, lettuce, beans, etc., where it ap- 
pears as a damping-off and rhizoctonia. 
See index. 
