Glomerella cingulata Associated with Leaf and Shoot Blight of Hybrid Poplar. G. Newcombe, Washington State University, Puyallup 98371-4998. J. M. Staley, and G. A. Chastagner. Washington State University, Puyallup 98371-4998. Plant Dis. 75:1286. Accepted for publication 6 August 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1286C.
Blighted leaves of hybrid poplar (Populus trichocarpa Torr. & A.
Gray × P. deltoides J. Bartram ex Marsh.) in plantations in western
Oregon, Washington, and British Columbia were sometimes found
to be infected with both Pollaccia elegans Servazzi (anamorph of
Venturia populina (Vuill.) L. Fabricius in Hollrung) and Colletotrichum
gioeosporioides (Penz.) Penz. & Sacco in Penz. (anamorph
of Glomerella cingulata (Stoneman) Spauld. & H. Schrenk). Perithecia
of G. cingulata and, less commonly, acervuli of C. gloeosporioides
were observed together with pseudothecia of V. populina on blighted
shoots during winter and spring. Surface-sterilized, detached poplar
leaves on filter paper soaked with gibberellic acid solution (100 µg/g) were inoculated with ascospores of G. cingulata or conidia of C.
gloeosporioides. In both cases, lesions developed within 24 hr that
gave rise first to acervuli, then to perithecia. Uninoculated control
leaves remained green for 3 wk or more and eventually died without
yielding C. gloeosporioides. Lesions developed on leaf blades, petioles,
and young stems of rooted hybrid poplar plants that had been sprayed
with a conidial suspension of a single-ascospore isolate of G. cingulata
and incubated 36 hr in a dew chamber (controls remained diseasefree).
Stem lesions did not, however, develop the shepherd's crooks
that occur after inoculation with V. populina. C. gloeosporioides, but
not G. cingulata, has been reported previously on Populus (I). Cultures
and voucher specimens of G. cingulata and C. gloeosporioides were
deposited in the herbarium of Washington State University (herb.