1. FOLIAGE and TWIG DISEASES (caused by Ascomycete fungi) and some Basidiomycetes (rusts) Reading: Dreistadt et al. p 185-191, 193-194, 212-213 Edmonds et al. Chapter 13

3. Mostly caused by Ascomycete fungi, but there are a few caused by bacteria and viruses (e.g., Camellia virus below). Abiotic causes (low and high temperatures, drought, air pollution, nutrition) are also important. General life cycle Ascomycote fungi Typically produce sexual ascospores in spring to infect new foliage and asexual spores (conidia) during the rest of the growing of the growing season. A few produce ascospores in fall. Both spore stages may not be produced.

4. TYPICAL LIFE CYCLE OF AN ASCOMYCETE FUNGUS FOLIAGE DISEASE Leaves fall in autumn or retained on plant Asexual spores (conidia) produced in summer continue to infect leaves Dead leaves overwinter Sexual spores (ascospores) produced in spring as new foliage emerges

5. Common foliage and twig diseases Dogwood anthracnose Sycamore anthracnose Cherry brown rot Rose black spot Conifer foliage diseases – Douglas-fir (Rhabdocline needle cast, Swiss needle cast) Pine needle casts. Rhododendron powdery mildew Poplar – shoot blight, rust Apple – scab and powdery mildew Azalea – powdery mildew Lilac – bacterial blight, Botrytis flower blight Peach – powdery mildew Winter injury – rhododendrons, pines

6. Common angiosperm foliage diseases – black spot, tar spots, leaf spots, sooty molds, powdery mildews, etc. Also sycamore and dogwood anthracnose (infect leaves and twigs). Common conifer foliage diseases – needle blights or needle casts

7. Apiognomonia sp. on Platanus Discula sp. on C. nuttalii Sycamore Anthracnose Dogwood Anthracnose

10. Cherry brown rot in Arboretum – Monilinia fructicola and M. laxa

11. Brown rot mummies

15. SWISS NEEDLE CAST ON DOUGLAS-FIR Heavily infected tree with loss of foliage Fruiting bodies (pseudothecia) plugging stomates

16. Elytroderma needle cast

17. Dothistroma needle blight

18. Rhododendron powdery mildew