In autumn, 1997, a powdery mildew on platanus occurred throughout the area of Tokyo, Japan. The fungus formed single conidia and multi-lobed appressoria on hyphae. Therefore, the fungus was identified as an Oidium sp. of the Erysiphe polygoni type. The pathogenicity of the fungus to three species of platanus was confirmed by replicating the disease symptoms in an inoculation experiment. Therefore, three species of platanus were added to the list of host plants of powdery mildew fungus. This report is the first record of platanus powdery mildew in Japan.
Stem and leaf rot disease of hybrid bouvardia occurred on the island of Oshima, Tokyo, in 2000. The causal agent isolated from the infected plants was identified as Sclerotinia sclerotiorum (Libert) de Bary by morphological observations and inoculation tests. This is the first report on the disease in Japan.
Gray mold and anthracnose of Stemona japonica (Blume) Miq. occurred in Hachijo-island of Tokyo Metropolis in 1999-2001. A Botrytis sp. isolated from the infected plants with gray mold was identified as Botrytis cinerea Persoon: Fries, while Colletotrichum sp. isolated from infected plants with leaf and stem blight were identified as Colletotrichum dematium (Persoon: Fries) Grove and C. gloeosporioides (Penzig) Penzig & Saccardo. Inoculation tests showed that these fungi were the causal agents of the respective diseases. This is the first report on these diseases in Japan.
Leaf spot of Miscanthus sinensis Anderss. var. condensatus (Hack.) Makino occurred in Aogashimaisland and Hachijo-island of Tokyo Metropolis in 1999. The pathogen isolated from the diseased plant was identified as a species of Stagonospora. An inoculation test confirmed that this fungus was the causal agent of the disease. This is the first report of this disease in Japan.
Pythium rot of Sansevieria trifasciata Pramn ‘Laurentii Compacta’ occurred in Hachijo-island of Tokyo Metropolis in 1999. A Pythium sp. isolated from the diseased plants was identified as Pythium spinosum Sawada. Inoculation tests showed that this fungus was the causal agent of the disease. This is the first report of the disease in Japan.
Seasonal prevalence of the bean bug, Riptortus clavatus, caught in water-pan traps baited with synthetic aggregation pheromone of this bug was compared with seasonal abundance of the bugs in a soybean field at Tsukuba in 2001. The population density of the adult bugs in the field showed a bimodal pattern with two peaks in mid-August and mid-September. On the other hand, a single peak was observed in the number of adult bugs caught by the pheromone traps in August by a trap placed beside the soybean field and in late September to early October by a trap in the experimental area near glasshouses. The population trend of the adult bugs caught in the traps in the soybean field was not synchronized with that observed in the field. These results suggest that the pheromone traps may not be an effective means to estimate their population trend in soybean fields.
Hyperparasitism of Neochrysocharis formosa (Westwood) on the primary parasitoid, Diglyphus isaea Walker, of Liriomyza trifolii (Burgess) was observed in a greenhouse of tomato plants where D. isaea was released. The percentage of the indigenous parasitoid, N. formosa, in the parasitoid complex emerged from L. trifolii larvae increased with time during June and July. Parasitism by N. formosa increased to 100% about two months after the first release of D. isaea. In this time, most of D. isaea larvae were hyperparasitized by endoparasites. All parasitoids emerged from D. isaea larvae were females of N. formosa. Body size of N. formosa emerged from D. isaea larvae was significantly smaller than ones which were emerged from L. trifolii larvae.
Effectiveness of control by the application of granular or wettable powder clothianidin against Liriomyza trifolii (Burgess) was evaluated in greenhouse tests on tomato plants. The control effect of granular clothianidin against L. trifolii was more effective than both nitenpyram and acephate. The larvae of leafminer did not occur on tomatoes for about 3 weeks after a granular application at planting. The application of clothianidin WP was more effective than acephate WP and flufenoxuron EC, and the mortality of middle-stage larvae by clothianidin WP was 36.6% and 54.2%. It was considered that clothianidin has the potential become to be one of the principal insecticides in tomato cultivation.
The ragweed beetle, Ophraella communa LaSage, was attacked on ragweed plants by the predators Harmonia axyridis (Pallas) larvae and adults, chrysopid larvae, mantid larvae and adults, Piocoris varius (Uhler) adults, and Agelena opulenta L. Koch nymphs. Of the 47 prefectures in Japan, distribution of the beetle expanded to 39 prefectures by the end of 2001.