Purple Blotch of Onion (Macrosporium Porri Ell.)

aerial mycelium alcohol alkaline Allium cepa Alternaria allii Alternaria Nees artificial media beaks beneath the cuticle blight BLOTCH OF ONION catenulate caused by Macrosporium cent conidia conidiophores conidiophores arising conidium cuticle decoction diameter distilled water epidermal fungi fungus germ tubes germ-tubes germination germination of conidia greenhouse growth and coloration host hyphae illus infected bulbs inoculation experiments inoculations isolations later leaf leaves and stems lesions longitudinal Macrosporium parasiticum Macrosporium porri Macrosporium solani medium mercuric chloride moist chambers mycelial growth mycelium names Alternaria obclavate conidia onion agar onion leaves onion stem organism parasite Petri dishes Phytopathology pigment plain potato agar plants potato-dextrose agar produced pure cultures Purple blotch Rands relation of temperature rotting scales scalpel wounds schleideni single-spore solution species of Macrosporium spores Sporulation stomata subcuticular sugar summer of 1926 thalli Thaxter 31 Thüm tissues varieties of onion water agar Welsh onions Wisconsin wound inoculations