Thirty one species from 10 botanical families were inoculated by root-dipping and planting in soil infested with 4 isolates of Fusarium oxysporum f. sp. radicis-lycopersici. Random sections from the roots and crowns of the 31 species were surface-sterilized and placed on Komada's Fusarium-selective medium. The colonies that formed on the medium were identified using a tomato seeding test as F. oxysporum f. sp. radicis-lycopersici. Ten cultivars of tomato except'Zuiken'and'Mato', Milk vetch, kidney bean, spinach and beet were highly susceptible. Eggplant, melon'Earl's knight natsu', broad bean, red clover and white clover were slightly susceptible. Growth of the roots was not good, and most of them were discolored. Eighteen cultivars from the Cruciferae, Umbelliferae, Compositae, Liliaceae and Poaceae were symptomless. But, F. oxysporum was reisolated from the roots of wheat, barley, radish, Chinese cabbage and so on, and identified as F. oxysporum f. sp. radicis-lycopersici with use of a tomato seedling test.

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Seasonal incidence of insect pests and their predators were investigated in watermelon fields of Wakayama Prefecture during 1982-1984. In the field with no insecticide applications, tetranychid mites (Tetranychus kanzawai and T. urticae) increased in number with the plant growth, reaching high densities at the harvesting period. The density of cotton aphid, Aphis gossypii, reached its peak during June and July. Thrips setosus was more abundant in the early growth stage of the plant, followed by the density decreasing with the plant growth. The most predominant predator, Orius spp., occurred during late June and early July. Scolothrips takahashii, Feltiella sp., and Amblyseius longispinosus increased in number after the increase of spider mites populations. Density increases of lady beetles (mainly Harmonia axyridis and Coccinella septempunctata), Syrphidae spp. and lacewings, Chrysopa sp., followed the occurrence of A. gossypii. Fewer predators were found in commercial fields with insecticides applications, compared with unsprayed fields. The abundant species of spider mite changed from T. kanzawai to T. urticae after acaricides application because of more susceptibility of T. kanzawai to acaricides.

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Sixty-eight genotypes of Cucumis melo (melon) and four wild relatives were evaluated for their response to sap inoculation of cucumber mosaic cucumovirus (CMV). Cucumis figarei, an African wild species, and three Asian genotypes of C. melo, viz., K-84-7, B-6 and W-7 were classified as highly resistant or immune because no symptoms were observed and no virus was presented 10 days after inoculation. C. figarei, K-84-7 and W-7 were tested for infection of cucumber green mottle mosaic tobamovirus, watermelon mosaic potyvirus-2, zucchini yellow mosaic potyvirus and melon necrotic spot carmovirus. Among these genotypes tested, only C. figarei was resistant to the above viruses. C. figarei was found to be infected with CMV only when inoculated on the first true leaf of young plants at 500 times (0.5mg/ml or higher) a concentration of purified virus, which uniformly infected the susceptible cultivar'Earl's Favourite', a typical netted melon in Japan. In C. figarei, CMV was restricted to the inoculated leaves. The rate of CMV multiplication in the inoculated C. figarei leaves, as estimated by the ELISA assay, was much lower than'Earl's Favourite' leaves. The results suggest that C. figarei is extremely resistant to the above mentioned viruses, which are important in cucurbits.

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Two virus isolates of filamentous particle were obtained from seedless Welsh onion (Allium fistulosum L.), cv. Bozushirazu that showed yellow streak symptoms. These viruses were identified as garlic latent carlavirus (GLV) and onion yellow dwarf potyvirus (OYDV) based on the results of host reaction, ISEM and DIBA with the antisera to GLV and OYDV. No symptoms were observed in the virus-freed Bozushirazu plants inoculated with GLV Distinct yellow streak symptoms were observed in the virus-free Bozushirazu plants inoculated with OYDV. The Bozushirazu plants inoculated with GLV and OYDV exhibited distinct yellow streak, most ofen sinuous symptoms of leaves. A field survey using DIBA revealed that all the Bozushirazu samples collected in Tottori prefecture were infected with GLV and OYDV. The rates of GLV or OYDV reinfected virus-free Bozushirazu plants in the provisional planting fields from June to September were 4% and 4%, respectively. GLV or/and OYDV reinfected virus-free plants in the field at GLV (9%), OYDV (6%), and GLV and OYDV (0%), respectively in autumn of the same year and at GLV (18%), OYDY (10%), and GLV and OYDV (16%) in the following spring. GLV or OYDV was translocated at the rate of 52%, 76% respectively from the plants of newly single virus reinfected Bozushirazu plants to the tillering plants which produced infected tillering plants without exception in the next generation. The tillering plants produced from GLV and OYDV infected Bozushirazu plants were infected at the rate of 95% with GLV or/and OYDV. The rates of infection in these tillering plants were GLV (18%), OVDV (10%), and GLV and OYDV (67%), respectively. There was not much difference in yield of the Bozushirazu plants singly reinfected with GLV or OYDV and the virus-free plants. The plant length and the leaf number of the plants reinfected with GLV and OYDV were lower than the virus-free plants and yield of the reinfected plants was only 18%. All the tillering plants produced from naturally infected plants were also infected with both viruses. The plant length, the leaf number and yield were only 5%, 15% and 27%, respectively. Yield of the plants reinfected with GLV and OYDV was significantly lower than the plants singly reinfected with GLV or OYDV, which indicates a possible synergistic relationship between multiplication of GLV and OYDV in the doubly infected plants translocated from reinfected plants to tillering plants.

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Natural enemies of the sweetpotato whitefly, Bemisia tabaci, were searched in the fields and in vinyl houses. Encarsia transvena, En. japonica, En. adrianae and Eretmocerus sp. were found in the fields. Chrysopa septempunctata and Propylaea japonica could emerge to adults reared on larvae of B. tabaci. The number of larvae of B. tabaci fed by a last instar larva of C. septempunctata were examined.

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Antiviral effects of a caramel composition (CC) diluted in 0.1 M phosphate buffer pH 7.0 were investigated. The application with CC by a small brush at a concentration of 10 to 100 μg/ml greatly reduced the number of local lesions produced by cucumber mosaic virus or tobacco mosaic virus in the infected leaves. The inhibition was observed in the plants applied with CC before or after the virus inoculation. The antiviral effects were also observed in different tissues from the CC-applied surfaces.

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First occurrence of Botrytis rhizome rot was noted in Japan on German irises. Botrytis convoluta, the pathogen, revealed a distinct difference in fine morphology of conidia and sclerotia from B. cinerea, when observed with a scanning electron microscope.

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