)aUsing the dissecting microscope, examine leaves of red oak (Quercus rubra) infected by the powdery mildew fungus. Notice the signs of disease, the white mycelium on the leaf surface and the presence of black cleistothecia.
)bIdentify the fungus to genus using the diagrams on the pathogen cycle and the key (see below).
()iPick off cleistothecia with a needle and razor blade and place them in a drop of water on a slide.
()aVerify the presence of cleistothecia in the drop of water by using the dissecting microscope or hand lens.
)aUsing a dissecting microscope, learn to recognize the distinctive fruiting structure of this fungus (elongated apothecia or hysterothecia).
.2Obtain balsam fir (Abies balsamea) needles infected with Isthmiella (= Bifusella) and learn to recognize the pycnidia (asexual) and hysterothecia (sexual) of this species. (http://www.na.fs.fed.us/spfo/pubs/howtos/ht_bfir/ht_bfir.htm) (class web site)
.3Examine Douglas-fir (Pseudotsuga menziesii) needles infected by Rhabdocline.
(http://www.na.fs.fed.us/spfo/pubs/howtos/ht_df-ndlcst/ndlcst.htm) (class web site)
)aCompare apothecia of this fungus with the hysterothecia of the previous two Ascomycetes and note the differences in shape, size, and location on the needle.
)bNote the pattern and color of necrotic tissue associated with this fungus.
)cExamine a prepared slide of infected needles with a compound microscope. Identify asci and ascospores.
.4Examine Douglas-fir needles affected by Swiss needle cast, incited by Phaeocryptopus (= Adelopus). (http://www.na.fs.fed.us/spfo/pubs/howtos/ht_df-ndlcst/ndlcst.htm)
)aIdentify the minute perithecia emerging from stomata.
)bNote how the necrotic tissue forms no distinctive pattern on the needles.
)cExamine a prepared slide. Label needle tissue, stomata, and perithecia.