200 CANADIAN JOURNAL OF PLANT PATHOLOGY, VOLUME 16, 1994 Figures 1-3. Aspen galls caused by the poplar budgall mite (<strong>Aceria</strong> <strong>parapopuli</strong> Keifer) near Dawson Creek, British Columbia; 1) Aspen trees with numerous stem galls; 2) Three large galls on one tree; 3) Close-up of gall showing red succulent tissue proliferations on the surface. This tissue contains living mites.
tremula L. and P. nigra L. in Europe (Wilson & Oldfield 1966). Galls caused by <strong>Aceria</strong> <strong>parapopuli</strong> are persistent and are generally found ringing the base of a developing bud or shoot (Keifer et al. 1982). Mites occupy galls for 1-4 years, or in rare cases, up to 10-15 years (Ives & Wong 1988). A 12- year-old mite-caused stem gall was reported from Miette Hot Springs, Alberta (Campbell et al. 1969). In the present study, stem galls from Hinton thought to be caused by this mite were at least 40 years old, and some of those from Dawson Creek are likely more than 80 years old. The irregular, cauliflower shape of the galls occurs because different areas have been inhabited by the mites at different times, induc ing abnormal surface proliferation and localized hyperplastic growth of the sapwood. A morphologi cal study of these galls and comparison with similar galls of unknown cause has been done (Crane 1993). It is impossible to determine at this time whether mite-infested aspen trees have a lower decay level than do surrounding nongalled trees because of the rare occurrence of large stem galls caused by the poplar budgall mite and a low incidence of Phellinus tremu lae at the site near Dawson Creek. The trees with mul tiple stem galls may represent an aspen clone that is particularly susceptible to poplar budgall mite. The potential of these mites as inducers of resistance mech anisms against decay organisms needs to be examined. We thank I.M. Smith, CLBRR, Biological Resources Division, Agriculture Canada, Ottawa, Ontario, for confirming the identifica tion of the poplar budgall mites. Voucher specimens have been deposited at CLBRR. We also thank R. Cooms and M. By!. Louisiana-Pacific Canada, Ltd., Dawson Creek, B.C., and D. Cheyne, <strong>Canadian</strong> <strong>Forest</strong> <strong>Service</strong>, for assisting with field surveys. Campbell, L.M., R.J. Bilodeau, and R.F. DeBoo. 1969. Research on the poplar gall-mite in the prairie provinces. Can. Dep. Fish. CRANE, HlRA TSUKA: ASPEN/STEM GALLS 20 I For., For. Branch, For. Res. Lab., Winnipeg, Manitoba. Internal Rep. MS-96. Cheyne, D.A. 1990. An introduction to market aspen bleached chemi-thermomechanical pulp. Pages 275-281 in R.D. Adams, ed., Proceedings of the aspen symposium '89, July 25-27, 1989, Duluth, Minnesota. USDA. For. Serv., North Cent. For. Exp. Stn., St. Paul. Minnesota. Gen. Tech. Rep. NC-140. Crane, P.E. 1993. Black gall on aspen: anatomy, histology, and relationship to decay. M .Sc. thesis, Department of Plant Science, University of Alberta. Edmonton. Alberta. Crane, P.E., P.V. Blenis, and Y. Hiratsuka. 1994. Black stem galls on aspen and their relationship to decay by Phellinus tremulae. Can. J. For. Res. (In press). Hinds, T.E. 1985. Diseases. Page 106 in N.V. DeByle and R.P. Winokur, eds., Aspen: ecology and management in the western United States. USDA. For. Serv .• Rocky Mtn. For. Range Exp. Stn., Fort Collins, Colorado. Gen. Tech. Rep. RM-I 19. Hiratsuka, Y., and A.A. Loman. 1984. Decay of aspen and bal sam poplar in Alberta. Environ. Can., Can. For. Serv., North. For. Res. Cent., Edmonton, Alberta. Inr. Rep. NOR-X-262. Ives, W.G.H., and H.R. Wong. 1988. Tree and shrub insects of the prairie provinces. For. Can., Can. For. Serv .. North. For. Cent., Edmonton, Alberta. Inf. Rep. NOR-X-292. Jeppson, L.R., H.H. Keifer, and E.W. Baker. 1975. Mites injuri ous to economic plants. University of California Press, Berkeley. Juzwik, J., W.T. Nishijima, and T.E. Hinds. 1978. Survey of aspen cankers in Colorado. Plant Dis. Rep. 52:906-910. Keifer, H.H. 1940. Eriophyid studies VIII. Bull. California Dep. Agric. 29:21-46. Keifer, H.H., E.W. Baker, T. Kono, M. Delfinado, and W.E. Styer. 1982. An illustrated guide to plant abnormalities caused by eriophyid mites in North America. USDA, Agric. Res. Serv., Agric. Handb. 573. Peterson, E.B., and N.M. Peterson. 1992. Ecology, management, and use of aspen and balsam poplar in the prairie provinces, Canada. For. Can., Can. For. Serv., North. For. Cent., Edmonton, Alberta. Spec. Rep. I. Thomas, G.P., D.E. Etheridge. and G. Paul. 1960. Fungi and decay in aspen and balsam poplar in the boreal forest region, Alberta. Can. J. Bot. 38:459-466. Wilson, N.S., and G.N. Oldfield. 1966. New species of eriophyid mites from western North America, with a discussion of erio phyid mites on Populus. Ann. Entomol. Soc. Am. 59:585-599.
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