SURVEY OF BLISTER RUST INFECTION ON PINES AT 
KITTERY POINT, MAINE, AND THE EFFECT OF RIBES 
ERADICATION IN CONTROLLING THE DISEASE 1 
By G. B. Posey, Pathologist , and E. R. Ford, Assistant Pathologist, Blister Rust 
Control , Bureau of Plant Industry , United States Department of Agriculture 
PINE INFECTION SURVEY, 1916-1918 
In 1916 an outbreak of white pine blister rust ( Cronartium ribicola, Fischer) 
was discovered in the southern part of York County, Maine. Extensive scouting 
during the same season revealed the rust present in varying degrees of abundance 
throughout southern Maine and adjacent New Hampshire. The oldest and 
severest attacks of the disease found in these regions were upon stands of native 
white pine ( Pinus strobus , L.) near a patch of cultivated black currants ( Ribes 
nigrum , L.) at Kittery Point, Me. These currants had been brought from Not¬ 
tingham, England, during the summer of 1897 and planted in a small garden 
surrounded by nearly pure stands of second growth white pine comprising mixed 
age classes. Systematic inquiry and search failed to show that any foreign 
white pine stock had been planted at or near Kittery Point, thus contradicting 
the supposition that the disease became established through that medium. The 
maximum ages of the more advanced rust lesions on pines in the immediate 
vicinity indicate that the establishment of blister rust at Kittery Point was 
coincident with the time when the patch of imported black currants was planted. 
This is further evidenced by the fact that the oldest pine infections found in that 
region are in the immediate vicinity of these currant bushes. 
In 1917 approximately 6 square miles of the infested area at Kittery Point 
were included in an experimental local control tract on which both wild and 
cultivated currant and gooseberry bushes were located and uprooted by syste¬ 
matic crew work. 2 Before eradication began a 31.5-acre block surrounding the 
patch of imported black currants was plotted and each pine, currant, and goose- * 
berry located for detailed investigation. 
In 1918 careful studies were made of conditions on the 31.5-acre tract to 
determine the severity of infection on pines and other facts relative to the spread 
of the rust. Results of these investigations are shown in the charts and tables 
which accompany the following discussions. 
DISTRIBUTION OF PINE INFECTIONS WITH RELATION TO THE PRESENCE 
OF RIBES AND THE INFLUENCE OF STORM WINDS 
The effect of different patches of Ribes in causing blister rust infection on pines 
was evidenced by the condition of the trees and stands nearest these bushes. In 
cases where the Ribes had caused pine infection, the amount of infection on pines 
varied according to the species, size, and exposure of the Ribes and was greatest 
on near-by pines. In several instances the Ribes were small and densely screened 
and apparently had not caused pine infection. (See fig. 1.) 
1 Received for publication May 9,1924—issued Nov. 1924. 
1 A crew consisted of 4 to 6 men in line, followed by a foreman. Intervals between line men varied accord¬ 
ing to the density of ground cover. In dense brush the interval was 6 feet or less while in open tracts the 
interval increased up to 20 feet. Efficiency was maintained by the constant checking of the foreman and 
by the crew systematically reworking definite units. 
Journal of Agricultural Research, 
Washington D. C 
( 1253 ) 
Vol. XXVIII, No. 12 
June 21, 1924 
Key No. G—445 
