Chapter VI Phycomycetes

Abstract

Publisher Summary This chapter focuses on phycomycetes. Synchytrium causes distortion of aerial vegetative parts and sometimes underground parts forming brown or orange galls or pustules (sori), the latter being like rust caeomata or sori. They contain one or few large thick-walled or many small thinner-walled spherical spores (resting spores and prosporangia), the latter resembling smooth aecidiospores. Physoderma causes brown streaks or patches on aerial parts, and galls on roots, particularly of aquatic and marsh plants. Under low power of the microscope the brown or golden resting sporangia can be seen through the transparent epidermis lying in masses in the cells of the tissues, not in sori. Purification of those fungi that are able to grow saprophytically may be achieved fairly readily by plating the primary material on plain water agar. Japanese agar is the most satisfactory; specially purified agars inhibit the growth of these fungi. The agar should be made up with non-toxic distilled water or tap water if it is non-toxic. If the plates have been poured a day or two beforehand, the surface will be dry and this will keep down bacteria. Pythium and Phytophthoru will usually outgrow bacteria on such a medium and as the hyphae grow fairly widely apart the tips of those clear of contaminants can easily be cut out and replated.