Beech Bark Disease A Clear and Present Danger to Our Hardwood
Transcription
Beech Bark Disease A Clear and Present Danger to Our Hardwood
Beech Bark Disease A Clear and Present Danger to Our Hardwood Forests Barry Davidson R.P.F. Forest Manager Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. What is Beech Bark Disease? A disease associated with two non-native causal agents: beech scale (Cryptococcus fagisuga) & Neonectria faginata And pathogen spores Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. Where did it come from? History (origin) beech scale introduced from Europe to the Halifax area ~1890 by 1930s tree mortality from BBD was observed in the Maritimes and Maine BBD in Quebec - 1965 first tree mortality north of Toronto in 1981 Muskoka area confirmed 2010 – near Vankoughnet/Baysville Currently a wide band from east of Dorset to Parry Sound First significant beech scale within/beside Killbear/Arrowhead Provincial Parks – coincidence or firewood?? Westwind Forest Stewardship Inc. Epidemiology (infection & spread) The infection process – beech scale The outer cells of the beech bark are altered by the scale feeding in such a way as to make them receptive for infection by the N. faginata. Reports of lag times between scale infestation and appearance of fungal infection range from ~2 to 10 years. Likely closer to 2 yrs here!! Westwind Forest Stewardship Inc. Lifecycle of the beech scale 1. 2. 3. 4. 5. Eggs hatch on beech tree (~mid-summer); Nymph, or “crawler”, finds suitable location on tree and forces its tubular mouthpart (“stylet”) into the bark, and begins to feed; Crawler then molts to immobile 2nd stage and produces wooly wax protective covering; Crawlers overwinter and molt to adult stage in the spring; Each mature adult scale (all are female parthenogenesis) lays 4-7 eggs in early summer. Westwind Forest Stewardship Inc. A predator of beech scale The twice-stabbed lady beetle (Chilocorus stigma) is a native species and a predator of beech scale. Both the adult and larval stages feed on scale – control not significant Westwind Forest Stewardship Inc. Cold winters will kill them? Might have some immediate reductions in scale but can survive below snow Some trees killed by infections on stump/root area Westwind Forest Stewardship Inc. Epidemiology (infection & spread) The infection process – fungal pathogen(s) N. faginata (or rarely Nectria galligena) infects bark cells altered by scale feeding; Pathogen colonizes a portion of bark as deep as the cambium, producing a canker; In fall the pathogen produces small, bright red perithecia which erupt through the bark; Infective ascospores are released from the perithecia during damp or rainy weather. Westwind Forest Stewardship Inc. Epidemiology (infection & spread) Spread (natural) tiny crawler stage can move from tree to tree on wind currents; on birds, insects mammals? Spread (assisted) on firewood & logs, especially during the crawler stage (mid-summer to late fall) Westwind Forest Stewardship Inc. Stages of Spread The Advancing Front …is characterized by… arrival and colonization of trees by scale alone Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. Stages of Spread The Killing Front …is characterized by… rapid build-up of scale infestation; abundant Neonectria infection and canker development; heavy levels of tree mortality. short timeframe from advancing to killing in Muskoka area Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. Stages of Spread The Aftermath Zone …is characterized by… lower scale populations; residual, defective and declining trees; perhaps a few resistant/ tolerant trees. Not there yet except in pockets Westwind Forest Stewardship Inc. Beech Bark Disease Resistance What about resistant trees? A very small percentage resistant to scale 1%? no scale No Beech Bark Disease Which one would you have picked? Westwind Forest Stewardship Inc. Westwind Forest Stewardship Inc. Marked 2012, Cut 2014, dead and dying 2015 with BBD Westwind Forest Stewardship Inc. Beech Scale movements, Disease Development, Dying Trees FAST Westwind Forest Stewardship Inc. Approach in French/Severn Forest Recently: Aggressive: 80% clumps plus leave only scattered individuals After international workshop this week: be even MORE aggressive Salvage material now, leave some pockets for mast production in short term We will NEED to greatly reduce beech regeneration Westwind Forest Stewardship Inc. X Westwind Forest Stewardship Inc. DID I MENTION WE MUST CONTROL BEECH REGENERATION?? $$$ Westwind Forest Stewardship Inc. 30-40 species eat beechnuts Westwind Forest Stewardship Inc. Beechnuts Acorns Corn Protein 11% 6% 11% Fat 17% 14% 3% Fibre 27% 18% 2% Sow reproduction after Mast year: 80% After non-Mast year: 22% Good NEWS? More dead and dying trees, for down woody debris AND in future years mast crops should recover from many small bad quality beech Westwind Forest Stewardship Inc. A more common sight? Westwind Forest Stewardship Inc. Best Management Practices Trees in urban and recreational areas 1. Trees with BBD often become hazard trees due to “beech snap” resulting from secondary decay fungi invading cankered areas. Removal is advised. Westwind Forest Stewardship Inc. 2. High-value trees can be protected from scale by: Physical control – removal of scale from accessible portions of the tree by high-pressure water wash; Oils – Application of dormant oil. Westwind Forest Stewardship Inc. Why is this forester not smiling for the camera? Westwind Forest Stewardship Inc. Our Future Beech? Westwind Forest Stewardship Inc.