598 
Journal of Agricultural Research 
Vol. XXX, No. 7 
In 1917 very heavy infection oc¬ 
curred, not only near the older infec¬ 
tions, but at considerable distances 
from Ribes. At the same time the 
rust became established in man}' 
localities where it had not been present 
previously. 4 In 1918 and 1919 aeeio- 
spore production was probably greater 
than in any previous year, yet infection 
was apparently less than in 1917, and 
the rust became established in few if 
any places where it was not already 
present. In 1920 the production of 
aeciospores was enormously increased, 
for the infections of 1917 resulted in 
aecia in 1920. No new centers of in¬ 
fection seem to have been established 
and heavy infection was confined to the 
immediate vicinity of fruiting cankers 
near Ribes. 
The field studies of 1923 showed the 
relatively greater amount of infection 
in 1921 than in 1920. (See Tables II, 
IV, and V.) Incipient, or 1921, in¬ 
fections were found in the Fraser 
Valley near Abbotsford, B. C., and in 
various places along the Pacific Great 
Eastern Railway, not only in localities 
in which no 1920 infections were found, 
but at much greater distances from the 
infecting Ribes than any of the 1920 
infections. They were found fre¬ 
quently as much as a mile from the 
infecting Ribes. The 1920 infections, 
on the other hand, were seldom over 
100 yards from the infecting Ribes. 
The infection of pine in the North 
Vancouver swamp illustrates very well 
the frequency of general or widespread 
infection. In Table VII it is shown 
that in the North Vancouver swamp 
there was infection probably in 1913 
and again in 1917. Further studies 
made in August 1923 by H. G. Lach- 
mund 5 showed incipient infections 
such as those noted in Table V. 
These indicate a third period of in¬ 
fection in 1921. 
From the tabulation given and from 
numerous field observations, the years 
of heaviest and most widespread in¬ 
fection appear to have been 1913, 1917, 
and 1921. As these waves or periods 
of infection can not be explained on the 
basis of abundance of aeciospore pro¬ 
duction, the attempt was made to 
correlate them with weather conditions. 
HISTORY AND DISTRIBUTION OF 
THE RUST 
It has already been shown that con¬ 
siderable infection of pine had occurred 
in British Columbia not later than 
1913. Infection occurred at North 
Vancouver, at various places along the 
route of the Pacific Great Eastern 
Railway, at least 60 miles north of 
Vancouver, and at Bold Point, Thurs¬ 
ton Bay, and Shoal Bay, a distance of 
125 miles northwest of Vancouver. 6 
There must have been considerable 
aeciospore production to have caused 
infection in so many widely separated 
places. 
The only place in which the rust is 
known to have been present in the 
Province at that time is Point Grey, 
near Vancouver. In May, 1922, David¬ 
son ( 1 ) found on Point Grey, near 
Vancouver, 180 eastern white pines 
(Pinus strobus), of which 68 were in¬ 
fected with the rust. Some of these 
had cankers in the growth of 1910. 
The 180 trees were all that remained of 
1,000 which had been imported in 1910 
from Ussy, France. Since infected 
white pines are known to have been 
shipped from Ussy in 1910 ( 7 , p. 36), 
it is altogether probable that some of 
the trees imported into Vancouver 
were already infected. If so, aecio¬ 
spores should have been produced by 
1913, and it is of course entirely pos¬ 
sible that they were produced in 1910, 
1911, and 1912 also. The plantation 
on which the infected trees were grow¬ 
ing was in an exposed situation upon 
one of the highest points of Point Grey, 
where the escaping aeciospores could 
have been caught easily by the winds 
and carried in every direction. 
It is known that some five-needle 
pines were imported into Victoria from 
Europe earlier than 1910. There is no 
evidence, however, to show that any of 
them were diseased, nor is there any 
reason to believe that any pines have 
been carried into or transplanted in 
the other places in British Columbia 
where early infection occurred. Nor 
is it likely that the rust was carried 
into the places outside of Vancouver 
on cultivated black currants, for al¬ 
though these plants are found fre- 
4 Lachmund, H. G. studies on white pine blister rust in the pacific northwest. Report for 
1923. [Unpublished. Typewritten copy in Office of Blister Rust Control, Bureau Plant Industry, U. S. 
Dept. Agriculture.] 
Pennington, L. H. field investigations of the white-pine blister rust in Washington and 
British Columbia. Report for 1922. [Unpublished. Typewritten copy in Office of Blister Rust Control, 
Bureau of Plant Industry, U. S. Dept. Agr.] 
5 Lachmund, H. G. Op. cit. 
6 See map (fig. 2) for localities mentioned. 
