Hold-Over Blight in the Pear 
5 
inches in diameter, and none contained living germs of blight. Ten of 
the samples varied in diameter from one-half to one inch, and the 
remaining four were water sprouts. The seven positive cases all oc¬ 
curred in the branches having a diameter of one-half to one inch, and 
four of these were small yearling twigs of 1909 growth. Only one 
series was examined for the season of 1909-1910. 
On Jan. 26 and 27, 1911, the first collection for the 1910-1911 
series was made. The winter was regarded locally as open with con¬ 
siderable snow and rain. At this time twenty-eight samples were se¬ 
cured representing three orchards, two of which were different from 
those used during 1909-1910. Virulent cultures of Bacillus amylovor- 
us were obtained from six or 21.43 P er cent, of these twenty-eight 
branches, and when 48 hr. cultures of the microorganisms isolated 
were introduced by needle pricks into the growing tips of pear seed¬ 
lings, one culture produced typical blackening in four days, two in 
five days and three in eight days. 
The second series was gathered from the same orchards April 
12 and 14, 1911. In one of the orchards, the peaches, apricots, cher¬ 
ries and plums were in full bloom. The pear buds had burst but the 
blossoms were showing no color. Apple buds were swelling. No 
oozing was observed from the blight cankers. In another orchard, 
the peaches, apricots and pears were in full bloom; the cherries and 
plums had already shed their blossoms. Apples were just beginning 
to show color. No oozing was visible. In the third orchard, peaches 
and apricots were in bloom, apple buds were about to burst, and the 
pear buds had opened but were showing no color in the blossoms. There 
was abundant oozing from the blight cankers on the larger limbs. In 
all, thirty-four branches and twigs were obtained, twenty-four of which 
came from the third orchard. The isolations were made April 21 and 
22, and of the total number examined in this series, eight or 23.53 P er 
cent, yielded virulent cultures of the blight organism. Five of these 
produced typical blackening of the pear seedlings in seven days, two 
in eight days and one in sixteen days. 
The following table, No. 1, may be of interest in showing the re¬ 
lation between the occurrence of B. amylovorus and the size of the 
twig, as well as the character of the microbic flora in the blighted area. 
