Spray inoculation with water suspension of conidia of Fusarium leaf spot fungus (Fusarium nivale (Fries) Cesati) was unsucceessful. However, the conidial germination and fusion of their germ tubes by which stomatal penetration was conducted were enormously promoted by the addition of polypeptone to spore suspension. Inoculation was accomplished by spraying spore suspensions containing 1% polypeptone and the inoculated plants were incubated in a high humidity chamber at 25-28C for more than 36 hours.
By passing juice from chrysanthemum leaves with mosaic or mottle symptom through a Sepharose 2B gel filtration column, fractions which gave infections on Chenopodium amaranticolor, zinnia, tobacco (Samsun NN and Bright Yellow) and Nicotiana glutionsa were recovered, whereas the unfiltrated juice was noninfectious. This recovery of fraction with infectivity was due to the elimination of several inhibitors in chrysanthemum by the chromatography.
Philodendron verrucosum Mattieu was shown to be a good local lesion host for dasheen mosaic virus. Other six Philodendron species so far tested were systemically infected with the virus, showing distinct mosaic symptoms. Anthurium scandens var. violaceum showed faint mottling of the leaves.
Expression of mosaic symptoms on young taro plants (Colocasia esculenta (L.) Schott) from dasheen mosaic virus infected corms was promoted by root cutting or high soil temperature (40C) at sprouting stage. Under field condition the percentage of taro plants showing mosaic symptoms was highest at the beginning of July, then decreased, and increased again after the end of August.
Small spherical virus particles were found in the phloem cells of broad bean plants infected with milk-vetch dwarf virus. The virus particles appear in the degenerated cytoplasm or in the vacuoles, forming amorphous, sometimes crystalline, aggregates. The virus particles could be partially purified by chloroform-butanol clarification followed by differential centrifugation. Their particle size is approximately 26nm in negatively stained preparations.
Rhizoctonia oryzae Ryker et Gooch, rice sheath spot fungus, grows little on the synthetic media consisted of inorganic compounds and glucose, but well by addition of rice decoction. Hyphal growth is promoted if thiamine hydrochloride was added in the synthetic liquid medium. Growth of the fungus is still more promoted by both thiamine hydrochloride and pyridoxine hydrochloride.