PLP 150C1 1st Edition Lecture 6Outline of Last Lecture I. Diseases caused by basidiomycetesA. ArmillariaB. Rusts & SmutII. Diseases caused by ascomycetesA. Powdery MildewsB. CankersC. ErgotD. Brown RotE. FusariumOutline of Current Lecture I. Chestnut BlightII. Dutch Elm DiseaseIII. White Pine Blister RustIV. Other plant diseasesCurrent LectureSudden oak death is caused by oomycetes. ***Chestnut Blight - there were so many of these trees, and they were huge. The ecosystems revolved around the trees. Birds, pioneers, lumber was resistant to rot. Then, strange disease noticed in the NY Botanical Gardens. Caused terribly cankers, & within 20 years it was in every chestnut tree pretty much. Culprit was an ascomycete, can reproduce sexually and asexually. Doesn’t kill the root system, just the tree. When it would hit a few years old, it would become infected. Reduced the Red Forest Giant to an understory bush. Literally they all die, and changed the ecosystem of Eastern Hardwood Forest.Controlling it:• Breeding programs. Cause we know the oriental chestnuts aren’t susceptible, just the american ones are. Breeding oriental & american chestnuts & checking for resistance. If it works, then breed those back into american chestnuts, & check for resistance. Years and years of back crossing to slowly remove most of the oriental genes except one of two oriental disease resistance genes.• Fungal Hypovirulence. There’s a virus that infects Cryphonectria that causes the fungus to be a less effective pathogen. It’s called hypovirulence. There’s a program to spread virus-infected fungi around the forest so all other fungi get infected. Trying to make the chestnut blight fungus weaker.Dutch elm disease - During WWI trenches were dug by Chinese who had brought wickerbaskets made of Chinese elm. Some of the baskets had the ascomycete fungus pathogen & a beetle that vectored the fungus. Millions of European elms died. Owner of a factory decided to import the European lumber, which is where the disease was. Imported logs & vectors that gave US the disease. Most cities lined their streets with beautiful elm trees. Millions of the elms died, changing urban landscapes across America.Controlling it:• Pruning disease trees. Remove dead/dying trees. Also reduces tree density, the beatles can’t fly far.• Insecticides. Spray infected trees.• Fungicides. No cure for dutch elm disease, but you can slow the impact by yearly injections of this.White Pine Blister Rust - A rust of a tree species. Came from Asia, where the trees have resistance, but our white pines don’t. It’s a heteroecious rust (has two hosts). The other hose is gooseberry, a common native bush. VERY destructive in forests harvested for lumber. Causes cankers & pustules. Controlling it:• Breeding programs. Similar to those for chestnut trees. Diluting out Asian White Pine genes.Nectria Canker of Beech - Came from Europe. A complex disease. it’s a wood disease that formsnasty cankers/leisures. Very destructive.Controlling it:• Control scale insects. And the trees are less damaged. It isn’t going to bring down the tree on it’s own. But with the fungus AND the insects, it will. Tar Spot of Norway Maple - Came from Europe. Doesn’t affect our maples, just theirs. It’s an urban tree problem. We do have our own species of tar spot though.Controlling it:• Reduce density of Norway Maple plantings in urban areas. Don’t plant them everywhere.Dogwood Anthracnose - Came from Asia. We don’t have these, but it was brought to US on Asian Dogwood & moved into the natural ecosystem. It affects every part of the small tree.Controlling it:• Not necessary in native areas. Disease resistance is naturally developing in our native dogwoods as resistant trees survive & reproduce. But in landscaped areas, spray whole tree with fungicide. Phytophthora Ramorum causing Sudden Oak Death - Started in west coast, which is known for Oak diversity. California western Oaks: dominant plants in their environment & keystone species. Exotic pathogen described in 2000. Discovered simultaneously in california oaks, & rhododendron & viburnum in Europe.Symptoms for sudden oak- it’s not a true fungus. Are Oomycetes. But symptoms are lesions, bleeding/oozing, and can kill adult trees.Symptoms for P. Ramorum - not host specific. Can kill young or mature plants.Controlling it:• Live with it..?• Quarantine all forest wood