Annual Report of the Kanto-Tosan Plant Protection Society

Verticillium sp. isolates from wilted chrysanthemum in Gunma Prefecture were identified and tested for their pathogenicity to chrysanthemum. In this study, all 20 isolates demonstrated pathogenicity towards chrysanthemum and were identified as V. dahliae. Pathotype analysis of the isolates indicated severe pathogenicity towards eggplants, and thus the isolates were classified as eggplant pathotype.

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Anthracnose of Reineckea, Reineckea carnea (Andr.) Kunth, and blue flax lily, Dianella caerulea Sims, occurred in Tokyo Metropolis in 2007. The causal fungus isolated from the diseased reineckea was identified as Colletotrichum dematium (Persoon: Fries) Grove. The causal fungus isolated from the diseased blue flax lily was identified as C. gloeosporioides (Penzig) Penzig & Saccardo. Inoculation tests showed that these fungi were the causal agents of the diseases. This is the first report on the diseases in Japan.

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The big-eyed bug, Piocoris varius, is a generalist predator that attacks pest insects and mites on vegetables in Japan. When the target pests are scarce, plant foods appear to be important for survival and/or development of the predator nymphs, as demonstrated in this study. Newly hatched P. varius nymphs survived 26.3 and 34.9 days and developed through several instars when offered flowers of sweet pepper and watermelon, respectively. However, they survived only a few days when offered other plant parts as foods from each plant tested. These results support our consideration, although P varius nymphs feeding exclusively on the plant foods tested did not lead to successful adult emergence.

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Adults and larvae of Asian lady beetle, Harmonia axyridis (Pallas), were discovered preying on the spider mite, Tetranychus kanzawai Kishida infesting leaves of tea shoots in an unsprayed tea field in 1992. When H. axyridis was given tea leaves infested with T. kanzawai in the laboratory, predation of spider mites by H. axyridis was observed. Furthermore, consumption of the adult female T. kanzawai prey by H. axyridis was investigated. Adult H. axyridis preyed on 41.5 spider mites per day when given 71 spider mites per leaf disk (diameter approx. 33mm), and larva preyed on 38.7 spider mites per day when given 40.7 spider mites per leaf disk. The three species of lady beetles, H. axyridis, seven-spotted lady beetle Coccinella septempunctata Linne, and Propylea japonica (Thunberg), were observed on the plucking surface of the tea bushes before the harvest of the first crop of tea. Adult H. axyridis were mainly observed. However, only a few larvae were on the plucking surface of the tea bushes in the tea season of the first crop, which is from the beginning of May until the middle of May. The number of adults increased after the middle of May. However, adults almost disappeared in June, whereas the number of larvae increased rapidly after plucking tea shoots in June.

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