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Disease Note. White Pine Blister Rust in Southern New Mexico. F. G. Hawksworth, USDA, Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO 80526. . Plant Dis. 74:938. Accepted for publication 16 July 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0938A. White pine blister rust (Cronartium ribicola J. C. Fisch.) was found
on southwestern white pine (Pinus strobiformis Engelm.) near
Cloudcroft, Otero County, New Mexico, in March 1990. The closest
known populations of this rust are about 1,000 km north in southern
Wyoming on P. f1exilis E. James and 1,400 km west in the southern
Sierra Nevada of California on P. lambertiana Douglas. Although
inoculation tests have shown that P. strobiformis is very susceptible
to the rust (1), this is the first report of the fungus in natural stands
of this host. The extreme isolation of the outbreak suggests that it
may have been a separate introduction rather than a result of spread
from previously known affected areas. The oldest infected area appears
to be 5 km northeast of Cloudcroft, where the rust has apparently
been established for at least 15 yr and several seedlings have been
killed. Scattered infected trees have been found up to 30 km south
and 19 km east of Cloudcroft. Plans are being developed to survey
this and adjacent areas to determine the distribution of the rust on
pines and on native and cultivated Ribes spp. and to estimate how
long the outbreak has been present in New Mexico. |