▁at ▁Grand - M ère ▁Q C ▁( L ach ance ▁ 1 9 7 8 ). ▁In ▁white ▁spr uce ▁plant ations , ▁mort ality ▁in ▁groups ▁of ▁ 2 ▁or ▁ 3 ▁trees ▁usually ▁occurs ▁at ▁about ▁age ▁ 3 0 – 3 5 ▁years ▁( Wh it ney ▁ 1 9 7 7 ), ▁but ▁younger ▁trees ▁can ▁also ▁be ▁killed ▁( Wh it ney ▁ 1 9 9 3 ). ▁Occ as ional ▁trees ▁as ▁young ▁as ▁ 1 0 ▁years ▁of ▁age ▁are ▁inf ected ▁( Wh it ney ▁and ▁Tim mer ▁ 1 9 8 3 ). ▁Se vent een ▁white ▁spr uce ▁plant ations ▁ 4 3 – 5 8 ▁years ▁old ▁in ▁Ontario ▁in cur red ▁an ▁average ▁of ▁ 0 . 7 % ▁mort ality ▁ann ually ▁over ▁a ▁ 6 - year ▁study ▁period ▁( Wh it ney ▁ 1 9 9 3 ). ▁A verage ▁accum ulated ▁mort ality ▁of ▁dominant ▁and ▁cod omin ant ▁trees ▁was ▁ 1 0 . 3 % ▁for ▁all ▁plant ations ▁in ▁that ▁study . ▁T oment os us ▁root ▁rot ▁was ▁found ▁in ▁more ▁than ▁half ▁the ▁st umps ▁after ▁clear cut ting ▁in ▁a ▁plant ation ▁at ▁Search mont , ▁Ontario , ▁but ▁decay ▁and ▁st ain ▁had ▁not ▁yet ▁reached ▁st ump ▁height ▁( Wh it ney ▁ 1 9 6 2 ). ▁ ▁Similar ▁species ▁ ▁Col tr icia ▁per ennis ▁is ▁similar , ▁but ▁has ▁a ▁weak ly ▁circular ly ▁z