PEAR DISEASES 345 
Paciric Coasr Rust 
Caused by Gymnosporangium Libocedri (P. Henn.) Kern = G. Blas- 
daleanum (Diet. and Holw.) Kern 
This is one of the recently recognized rusts of the pear family. 
The name Pacific Coast rust is used in contradistinction to 
eastern rust of pear (see page 341). The disease here consid- 
ered was discovered in Oregon on cultivated pear several 
vears ago, but was first given special attention in 1907. Since 
that date it has been found annually in Oregon and was par- 
ticularly abundant in 1913. It is believed on good authority 
that this rust will in time become one of the most important 
pear troubles within its present range. It is most common on 
the native hosts, Oregon crab and its apple-hybrids, the haw- 
thorn and service-berry. It also occurs on the ornamentals 
mountain-ash, Japanese 
quince, Japanese pear 
and flowering crab. It 
is common on the cul- 
tivated quince, but is 
rare on the cultivated 
apple. 
Symptoms. 
The foliage (Fig. 95), 
fruit (Fig. 96) and stems’ 
are affected, and in each 
case there results some 
distortion. Yellow or 
orange spots develop 
on the affected parts; 
within the discolored area cup-like bodies with white 
margins are visible to the unaided eye. The fungus affects 
the incense cedar (Libocedrus decurrens), symptoms show- 
ing as brownish pustules on the leaves (Fig. 97). Some- 
Fie. 95. — Pacific Coast rust on pear-leaves. 
