Impact of Eutypella Canker on the Maple Resource of the Owen Sound and Wingham Forest Districts
Sugar maple (Acer saccharum Marsh.) stands of the Owen Sound and Wingham districts in southwestern Ontario were sampled to assess the importance of cankers caused by Eutypella parasitica Davidson and Lorenz. Stands in the Owen Sound District had Eutypella cankers on 7.4% of the sugar maples. Cankered trees had an average cull loss of 12.4% total cubic volume and 49.2% merchantable cubic volume. The incidence of cankering was significantly less for the Wingham District where maple stands have better overall timber quality than do stands in the Owen Sound District. The incidence of Eutypella canker was a positive function of the percentage content of maple in a stand, maple tree density, and maple tree size. Cull loss due to cankers was related to canker size and tree size and to the position of the canker with respect to log production. Regression models illustrating these relationships are presented.