FUNGI AND FUNGOUS DISEASES OF PLANTS 261 
Crass IIT. Fuxer 
Sus-cLass I. Paycomyceres (the alge-fungi). Leading genera 
used as illustrations — Rhizopus (bread mold), P/asmapara 
(grape downy mildew), Phytophthora (potato blight) 
Stup-crass I]. Ascomycetes (the sac fungi). Leading genera 
used as illustrations — Sclerotinia (brown rot), -Wiscrosphaera 
(lilac mildew), JVorchella (morel), Penicillium (blue mold), 
Saccharomyces (yeast) 
Scus-cLass JIT. Licnens. Leading genera used as illustrations 
— Parmelia, Usnea (bearded moss), Cladonia 
Scus-cLass IV. Basipiomyceres (the basidium fungi). Leading 
genera used as illustrations — Ustilago (smut), Puccinia (rust), 
Coprinus and Polyporus (mushrooms), Lycoperdon (puftball) 
PROBLEMS 
1. Why does bread “mold”? How can it be prevented from doing so? 
2. Why is it that a plant disease newly introduced into a country 
seems to spread more rapidly and to prove more destructive than 
diseases that have long been in that country? 
3. Can you account for the fact that lilac bushes seem to be fairly 
thrifty even though they are infested with lilac mildew? 
4. Why are lichens sometimes called “the advance guard of vege- 
tation”? 
5. If you can secure the data from published reports, or can perform 
an experiment for the purpose, determine the difference in yield that 
may be made by selecting or treating seed oats or corn so as to remove 
the smut disease. What percentage of gain on the crop may be made 
in this way? 
6. Under what circumstances may fungi that are parasitic upon 
plants or animals be of service to the farmer or gardener? 
7. Why are railroad ties and other timbers often treated with poison- 
ous solutions before they are used? 
8. Discover from first-hand study or from publications the life history 
of some of the worst fungous parasites of your locality. 
