DISEASES OF CULTIVATED PLANTS 42> 
PEAR 
Anthracnose. An anthracnose fungus (Colletotrichum sp.) occurs upon the 
fruit of the pear in the east, but has not been seen in Ohio. 
Black-Rot (Sphaeropsis malorum Pk.) of the pear is the name applied to the 
rot like that of the quince and apple and due to the same organism. While it is 
less frequent as a source of fruit rot upon the pear, it is present both in this 
form and in the form of branch attacks or cankers. 
Pear Blight or Fire Blight is one of the most serious drawbacks to pear 
growing. The symptoms of dead twigs and branches are well known, In sub- 
stance our knowledge of pear blight is about this:—It is due to a bacterium 
(Bacillus amylovorus (Burr.) which, in the old cases of blight, winters over in 
the blighted parts. With April and May showers there is some exudation of 
watery substance from these parts, containing the zoogloa masses of the bac- 
terium; when visited by insects these are by them transmitted to the opening 
blossoms. The microbe there breeds in the nectar of the blossom and in that 
manner attacks the branches; once within the tissues the microbe may spread 
indefinitely. Some varieties of pears are more susceptible, apparently, than 
others, which simply means that in them the. microbes spread more rapidly. 
There is not a single variety of blight-free pear in our region. The remedy con- 
sists in cutting off and burning the blighted parts 
each autumn, extending the work to the crab-apple, 
apple and indeed to every variety of pome fruit which 
is attacked by this bacterium. In recent years Mr. 
Wm. Miller, of Ottawa County, has reported better 
results in blight control since he practices thorough 
spraying of the trees in early spring with lime-sulfur. 
(Bulletin 79. Year-book U. S. Dept. of Agric. 1895). 
Crown Gall. The crown gall attacks the pear both 
at the crown and upon tips of roots. It is less rapid 
in its destructive effects here than upon the peach, 
though but slightly less serious. Enlargements may 
be readily detected and they are usually of denser, 
woody growth than upon the peach. The same rem- Fig 78. Grown Gall on end 
edies apply here as with that fruit. of pear root. 
Leaf Blight of the pear is produced by the leaf 
blight fungus (Zxtomosporium maculatum Lev.) which causes spotting and dying 
of the leaves, also cracking of fruit. The diseased leaves show a dense, dark 
colored coating on the under side. This disease is readily and successfully 
prevented by the use of Bordeaux mixture as a spray. 
Leaf-Spot of pear is another fungus disease which may flourish despite the 
use of Bordeaux mixture, as generally applied. This fungus (Septoria piricola 
Sacc.) appears not to yield to the standard fungicides. It produces small, cir- 
cular dead spots in the leaves; the spots in later summer may drop out, leaving 
holes. It is quite prevalent, but as yet -no specific recommendations can be 
made for it. 
Pear Scab is a fungus disease allied to Apple Scab; the pear. scab fungus 
(Fusicladium pirinum (Lib.)Fuckl.) being very similar in development to that of 
apple scab. This fungus was very abundaut in 1898. It may cause spotting of 
the leaves or spotting of the fruit of the pear but is not readily distinguished 
from the other troubles save by the use of the microscope. It is prevented by 
the use of Bordeaux mixture. : 
