Apr. 1, 1925 
Relation of Weather to White Pine Blister Rust 
607 
In 1923 infection was found on Ribes 
at Namu and Bella Coola, 80 and 
110 miles, respectively, north of the 
limit of white pine upon the coast. 
Prevailing westerly winds favor aecio- 
spore dispersal from the coast toward 
the east. 
Northerly winds, which favor aecio- 
spore dispersal to the south, are most 
common in dry seasons, which are un¬ 
favorable for pine infection. 
West of the Cascades, northerly 
winds in the period of aeciospore pro¬ 
duction increase to the southward as 
far as northern California. 
The amount of summer precipitation 
diminishes southward. 
The rust is practically certain to 
spread southward at a much slower 
rate than to the north and east. 
The spread of the rust to the “ Inland 
Empire” may be greatly retarded by 
the elimination of Ribes nigrum from 
that region. 
LITERATURE CITED 
(1) Davidson, A. T. 
1922. WHITE PINE BLISTER RUST IN BRITISH 
COLUMBIA (REPORT ON CANADIAN CONDITIONS 
and work). Rpt. Proc. & Rec. Western 
White Pine Blister Rust Conf. 3: 9-22. 
[Mimeographed] 
( 2 ) - 
1924. RESULTS OF PAST SEASON’S WORK, PRESENT 
SITUATION AND FUTURE PLANS. Rpt. PrOC. 
Meeting Trust. Western White Pine Blister 
Rust Conf., Spokane, Wash., Jan. 7-8, 1924. 
[Mimeographed] 
(3) Denison, F. N. 
1923. CLIMATE OF BRITISH COLUMBIA. Brit. 
Columb. Dept. Agr. Bui. 27, 15 p. 
(4) Heald, F. D., and George, D. C. 
1918. THE WIND DISSEMINATION OF THE SPORES 
OF BUNT OR STINKING SMUT OF WHEAT. Wash. 
Agr. Exp. Sta. Bui. 151, 23 p., illus. 
(5) Larsen, J. A. 
1924. DUST STORMS OF NORTHERN IDAHO AND 
western Montana. Jour. Forestry 22: 576- 
577. 
(6) Snell, W. H. 
1920. OBSERVATIONS ON THE DISTANCE OF SPREAD 
OF AECIOSPORES AND UREDINIOSPORES OF CRON- 
artium ribicola. Phytopathology 10: 358- 
364. 
(7) Spaulding, P. 
1911. THE BLISTER RUST OF WHITE PINE. U. S. 
Dept. Agr., Bur. Plant Indus. Bui. 206, 88 p., 
illus. 
(8) - 
1922. INVESTIGATIONS OF THE WHITE PINE BLISTER 
RUST. U. S. Dept. Agr. Bui. 957, 100 p., illus. 
(9) Stakman, E. C., Henry, A. W., Curran, 
G. C., and Christopher, W. N. 
1923. spores in the upper air. Jour. Agr. 
Research 24 : 599-606, illus. 
(10) York, H. H., and Snell, W. H 
1922. EXPERIMENTS IN THE INFECTION OF PINUS 
strobus with cronartium ribicol f . Phyto¬ 
pathology 12: 148-150. 
