600 
Journal of Agricultural Research 
Vol. XXX, No. 7 
There is no evidence that infection 
in these widely scattered centers was 
caused by the introduction of diseased 
pines or Ribes. No five-needled pines 
were found, except native Pinus mon- 
ticola. 
Since 1912, and particularly during 
the period of the war, there seems to 
have been very little transporting or 
planting of ornamental stock in British 
Columbia. The infections in pine were 
found in native trees in the immediate 
vicinity of old black currant bushes. 
The bushes at Revelstoke were said 
to have been brought from eastern 
Canada in 1898. It would have been 
a very unusual thing if the rust had 
been introduced into any one of these 
places upon pines or Ribes. That it 
should have been introduced into three 
or four widely separated places is prac¬ 
tically outside the range of possibility. 
The Canadian scouts were unable to 
find any evidence that the rust had 
been introduced upon either pines or 
Ribes. 
Little is known of the distribution of 
infection upon Ribes previous to 1922, 
except as it is indicated by the infec¬ 
tion of pines. A little scouting was done 
late in the season of 1921 and some in¬ 
fection found upon cultivated black 
currants in the Puget Sound region near 
Port Townsend, Everett, and Mount 
Vernon, Wash. A great deal of scout¬ 
ing for the rust was done in 1922. In¬ 
fection was found upon black currants 
in the Pemberton Meadows and near 
Mable Lake, B. C., and occasionally 
upon wild Ribes in many places in the 
Puget Sound region, near Forks, Grays 
Harbor, and in the vicinity of Willapa 
Bay, Wash. The black currant infec¬ 
tions in the Willapa Bay region in the 
extreme southwestern part of Washing¬ 
ton were fully 200 miles from the nearest 
known infection upon white pine and 
many miles from any 5-needled pines. 
In 1923, infection was found upon 
susceptible wild Ribes in the Puget- 
Sound region as far south as Chimacum, 
near Port Townsend. The cultivated 
black currants in this part of the State 
had been removed in 1922. No infec¬ 
tion was discovered upon either the 
cultivated black currants or the wild 
Ribes in the Willapa Bay region. On 
the other hand, cultivated black cur¬ 
rants were found infected at 26 places 
in the dry belt and the Columbia and 
Kootenay River Valleys in British 
Columbia. 9 On the coast infection was 
found at Namu and Bella Coola, 80 
and 110 miles, respectively, north of 
the northern limit of white pine (1, 2 ). 10 
WINDS IN THE NORTHWEST 
The period of aeciospore production 
was found to be long and to vary con¬ 
siderably in different years. In 1922 
aecia began to break open by the first 
week in May. The heaviest spore dis¬ 
persal was between about May 15 and 
June 15. Considerable quantities of 
fresh aeciospores were found at Van¬ 
couver as late as July 5 and some were 
found in the mountains as late as July 
18. In 1923, aecia began to break open 
the first week in April. The heaviest 
spore dispersal was between April 15 
and May 15. Very few aeciospores 
were seen as late as June 29. 
Possible agents for aeciospore dis¬ 
tribution are winds, birds, animals, and 
man. It is scarcely conceivable that 
any considerable number of the Ribes 
infections in Washington or in British 
Columbia in either 1922 or 1923 could 
have been caused by spores carried by 
man. The large majority of the 
bushes had not been seen by any per¬ 
son who had been in the vicinity of 
infected pines before those bushes were 
discovered with infection. There are 
no other migrating animals which 
could have carried spores over the 
wide area in which infected Ribes 
were found. 
Migratory birds move along the coast 
or north or south in the interior. They 
do not migrate east and west across 
the mountains. The species and sub¬ 
species of birds east of the Cascade 
Divide are largely different from those 
along the coast. It is very unusual 
to find a bird from the interior west of 
the Cascade Divide. Ribes infection 
in Washington was found before the 
migrating birds had returned from the 
north. The infections at Namu and 
Bella Coola are the only ones which by 
any stretch of the imagination could 
have been effected by birds. On the 
other hand, spores carried by winds 
may account for the infection wherever 
it has been found upon Ribes. 
It is a well-known fact that the pre¬ 
vailing winds of the temperate regions 
of the earth’s surface are from the west 
or southwest. Cyclones and anti¬ 
cyclones about centers of low or high 
barometric pressure cause temporary 
but more or less periodic variation in 
the direction and velocity of winds. 
The topography of the earth’s surface 
9 See map for localities. 
10 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 of Plant Industry, 
U. S. Dept, of Agriculture.] 
