>Date: Fri, 30 Aug 1996 19:39:51 -0400 >From: Gerry Hawkes <ghawkes@SOVER.NET> >Subject: Severe browning of Populus balsamifera > >For the last month widespread, severe browning of Balsam Poplar (Populus >balsamifera) has been evident throughout central Vermont. This appears >to be affecting all Balsam Poplars and some Quaking Aspen (Populus >tremuloides). Leaves are completely brown and dead on the entire trees, >except for a few shoots of this year's growth at the very tops. > >Does anyone have an explanation? Who is (or isn't) seeing the same problem >(let us know where you are)? > >- Gerry Hawkes - Woodstock, Vermont - ghawkes@sover.net > >------------------------------ Hello, The browning of Balsam poplar (Populus balsamifera) observed by Mr. Hawkes is present in New Brunswick in eastern Canada and I assume that this is the same browning that I saw in northern Maine, U.S.A. last week. The cause, here in New Brunswick, is the asexual Septoria musiva stage of a fungus called Mycosphaerella populorum. It is described by G.E. Thompson in Phytopathology Vol 31: 241-254, 1941. In New Brunswick and the neighbouring provinces of Nova Scotia and Prince Edward Island, the browning of Trembling or Quaking aspen (Populus tremuloides) is caused by the asexual Marssonina brunnea stage of a fungus called Drepanopeziza tremulae. K.A. Pirozynski has a good description in Fungi Canadenses No. 13, May 1974 (as Marssonina brunnea). The wet spring and early summer weather were ideal for fungal infection here. It is possible that you may have a variety of insects including leaf beetles, flea beetles or leafminers present and causing visually similar damage in Vermont on Balsam poplar and Quaking aspen, so it would be important to verify whether these fungi, leaf rusts or insects are present; either alone or in combination. Regards, Ken Harrison Disease Identification Officer Forest Health Network Canadian Forest Service Atlantic Forestry Centre P.O. Box 4000, Regent Street South Fredericton, New Brunswick Canada E3B 5P7 Tel: 506-452-3513 Fax: 506-452-3078 E-mail: KHarrison@fcmr.forestry.ca
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