First Report of Ceratocystis fimbriata Infecting Balsam Poplar (Populus balsamifera).

Abstract

This is the first report of Ceratocystis fimbriata Ellis & Halst. (Ophiostomatales) (anamorph: Chalara sp. (Corda) Rabenh.) associated with symptoms of perennial canker on small branches and wilt of leaves and twigs on balsam poplar (Populus balsamifera L.). The fungus is known to occur on trembling aspen (P. tremuloides Michx.) (1) throughout the mountainous West and extends eastward to Quebec and Pennsylvania (2).These tree species are common in the boreal and Rocky Mountain areas of North America. In April 1999, the disease was observed on cuttings (15 × 1 cm) collected from the terminal branches of young balsam poplar trees (h = 4.5 m) near Baie Comeau located 350 km northeast of Quebec City (48°61', 68°21'), Quebec, Canada. Apparently healthy cuttings were potted in a soil mix (peat moss and vermiculite, 3:1 vol:vol), grown in a greenhouse at 22 ± 1°C and watered twice a week. About 2 weeks after bud break, a number of cuttings were symptomatic, showing necrotic bark lesions and cankers, discoloration and wilting of leaves, and reddish brown exudate surrounding leaf petioles. During the following two weeks, 22% of the cuttings died (212 out of 958). The fungus was isolated from diseased cuttings on 2% MEA (malt extract agar), from the necrotic bark around active cankers (2 × 1 cm), from brown to black streaks found in vascular tissue, and from the ascomata found on the canker margin and inconspicuous necrotic roots. From necrotic petioles, one other opportunistic fungus, Aureobasidium pullulans (de Bary) G. Arnaud, was occasionally isolated. The inoculum for infection of the balsam poplar may have originated from neighboring trembling aspen trees. We believe that C. fimbriata could have a negative impact on reforestation efforts unless phytosanitary inspections are made of the planting stock.