PLPA 2010 1st Edition Lecture 8Outline of Last Lecture I. Rust FungiOutline of Current Lecture II. Plant Diseases III: TreesCurrent Lecture- Tree Diseases:o Chestnuts: Lots of chestnuts in America in 20th century Cryphonectria Parasitica: fungus introduced from Asia, where it doesn’t cause much trouble. Makes a canker in the tree that girdles and kills the tree. Can reproduce sexually (genetically diverse, faster)/asexually Deadly to our American chestnuts Blight spread rapidly from the east coast in It got just about everywhere by the 1940’s (ecological catastrophe) 4 billion trees died within 40 years There are still chestnuts around here, sprouting from stumps dead almosta century but they rarely get big enough to fruit For the last 70 years, scientists have been trying to breed a resistant chestnut tree. Interbreed Asian and American chestnut treeso Tar Spot: Rhytisma spp.: In silver and red leaves Each tar spot is a point of infection- Where a spore hit the growing leaf In a bad year, tar spot might defoliate the tree But the trees survive, make new leaves After spending winter on the ground, the spots split open and shoots spores just as new maple leaves are forming Ascospores are like needles A little raking can decrease the disease Fungicide sprays aren’t really needed Although homeowners get upset, we are not so worried about maples- Lots of tree diseases fall into this categoryo Sudden Oak Death:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Caused by phytophtora ramorum - Tree Diseases in General:o Every kind of tree is affected by many kinds of diseaseso Normally, tree diseases kill the weak and the strong surviveo Trees and their pathogen are engaged in a constant, slow evolutionary battle- Managing Plant Diseases:o In agriculture. We rely on: Breeding new resistant varieties of plants that can completely or partially resist pathogens Treating crops with fungicideso These strategies are hard to apply to forest trees- Global Trade and Diseaseo Our most devastating trees diseases are often introductions from elsewhereo When a foreign pathogen is introduced to a place where the trees haven’t met it before.. The rate of disease introductions is increasing:- Chestnut blight- Dutch Elm
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