4 
Colorado Experiment Station. 
biochemical methods, they were all inoculated into pear seedlings in 
order to determine their virulence. 
EXAMINATION OF MATERIAL. 
The first collection of hold-over blight material, tagged during 
the summer of 1909, was made Feb. 28, 1910. At this time twenty-one 
specimens were obtained representing three different orchards. (From 
InoeuistM 
' 4 ' - 
Control 
S ’ 
Inoculetod 
colo rxMr $rA 
Fig. 1. A and C. Two pear seedlings five days after being inoculated with 
cultures of B. amylovorus isolated from hold-over canker April 21, 1911 
colo. expr.srA 
Fig. 2. Hold-over canker on pear twig showing characteristic cracking from 
which the oozing takes place. 
seven of these, or 33.33 per cent, cultures of B. amylovorus were ob¬ 
tained. Three of the limbs were between one, and two and one-half 
