An Apricot Blight. 
7 
Nine apple twigs were inoculated on the same day with the 
fresh diseased tissue from apricot fruits. The disease spread in all 
of these twigs, killing them from the tips down ; in one instance 
ten inches of the twig from the tip, back, was dead. No differ¬ 
ence could be detected in the appearance of these twigs and in 
those that were known to have been killed by pear blight. Both 
leaves and twigs shrivelled and turned dark colored and drops of 
sticky fluid exuded from the bark and from the leaf stems. 
On the same day, June 30, sevenjapple twigs were inoculated 
with fresh diseased tissue taken from a blighting apple limb. 
These inoculations were made for the purpose of comparing the 
disease produced with that produced with germs taken from apri¬ 
cot fruits. All of the twigs developed typical cases of pear blight, 
becoming shrivelled, dark colored and exuding drops of sticky 
fluid. The twigs in this lot could not be told from those that 
had been killed by inoculating with diseased tissue from an apri¬ 
cot fruit. The bacteria appeared to be the same when examined 
with a microscope and made the same growth when cultivated 
artifically in the laboratory. 
There was no blight in the trees on 
which these experiments were made and 
to make sure that the mechanical injury 
of inoculation could not cause the twigs 
to die or the fruit to decay, control or 
check twigs and apples were carried 
along with all the experiments. These 
were made by making incisions with a 
sterile knife through the skin of the apple 
or through the bark of the twigs; the 
wounds were then covered with sterilized 
grafting wax. No disease developed in 
any of the checks and the injuries soon 
healed. 
These experiments were repeated a 
number of times with cultures of the bacteria taken from apple 
twigs, apricot twigs and apricot fruits. Inoculations were made 
in both apple twigs and fruit and the results were the same, 
namely, a typical case of pear blight from all three sources. 
As there are no apricot trees growing on the College grounds, 
Mr. J. S. McClelland kindly offered the use of one of his trees for 
experimental purposes. A number of inoculations were made in 
the twigs of this tree July 8. Cultures of the disease obtained 
from apple twigs, apricot twigs and apricot fruit were used. The 
orchard was visited on July 20 when it was found that blight had 
been produced in a number of the inoculated twigs, while the 
check twigs remained sound. 
Fig. 2. Apple inoculated with 
tissue from apricot twig; the 
latter having been inoculated 
with a culture of pear blight. 
