ESRM 451 URBAN PLANT PROTECTION – SPRING 2010 Lab 3 – Basic Plant Pathology 1. Airborne spores and bacteria Examine the 2% malt agar Petri plates you exposed for an hour inside the lab and outside last week. Count the number of fungal and bacterial colonies. Express your counts as number deposited per square meter per hour. 2. Disease and disease causing organisms There are seven types of organisms causing plant diseases; viruses, viroids and prions; phytoplasmas; bacteria; fungi; parasitic plants; nematodes and protozoans. In this lab we will examine diseases caused by viruses, bacteria, parasitic plants (true and dwarf mistletoes) and fungi. In your teams examine the features of the diseased plants and pathogens. 2.1. Viruses – examine the camellia plant with Camellia virus 2.2. Bacteria – examine bacterial galls on Douglas-fir branches 2.3. Parasitic plants - mistletoes a. True mistletoe – Phoradendron on oak – note branch swellings on host, and true leaves and stems of mistletoe plants b. Dwarf mistletoe – Arceuthobium on hemlock – note brooming and swelling of branches, and tiny segmented plants with no true leaves. 2.4. Fungi 2.4.1. Features of fungi Vegetative hyphae of fungi – cell walls, cross walls (septa) Spores - Examine rust spores and conidia under the microscope. Describe the spore features; size, shape, spore wall thickness, pigmentation, ornamentation. 2.4.2. Fungal Phyla – compile a table showing the features of: Ascomycota, Basidiomycota, and Oomycota (fungal-like organisms) (mycelium, sexual spores, asexual spores, diseases caused) 2.4.3. Some common diseases Decay – brown and white rot Ganoderma applanatum (Artist conk) – white rot Phaeolus schweinitzii (Velvet top fungus) – brown cubical rot Cankers Madrone canker – Neofusicoccum arbuti 1Rusts White pine blister rust – Cronartium ribicola Western gall rust – Endocronartium harknessii Oregon Grape rust - Foliage diseases Rose black spot – Diplocarpon rosae Swiss needle cast – Phaeocryptopus gaeumannii Root diseases Armillaria ostoyae – Armillaria root disease Phellinus weirii – Laminated root rot Heterobasidion annosum - Annosus root and butt rot - Report (due next week April 22, 2010) 1. Draw diagrams indicating the features you saw or use digital cameras or web based materials. Use the headings above. For each of the specific diseases list: (a) the disease name, (b) causal organism, (c) main host(s) and (d) management. 2. Answer the following questions. 2.1. How are spore features related to the spread and expression of disease for each of the spore types; i.e., what is the purpose of pigmentation, how far can spores travel? 2.2. What does the spore deposition data tell you about the spread of disease? Are there more fungal spores than bacteria? Why? 2.3. Why are there more spores deposited outside than inside on your Petri plates.