Downy mildew of rocket (Eruca vesicaria ssp. sativa) and leaf mustard (Brassica juncea) occurred in Tako, Chiba on July 2003. Both causal agents were identified as Peronospora parasitica (Persoon: Fries) Fries. Physiological specialization of both fungi were different from each other and those of already-known P. parasitica. This is the first report on these diseases in Japan.
Of the 34 isolates of Broad bean wilt virus collected from 18 prefectures in Japan during 1962 to 1999, and 122 field samples collected from 9 prefectures in 1997 to 2000, a large number of samples reacted strongly with an antiserum against Broad bean wilt virus 2 (BBWV-2) in a double-antibody sandwich enzyme-linked immunosorbent assay. One of these isolates that reacted strongly with the antiserum against BBWV-2 and also reacted weakly with an antiserum against Broad bean wilt virus 1 (BBWV-1), was used for further analysis. Sequence analysis of the coat protein genes indicated that they belonged to BBWV-2. Thus, all the plants in 15 kinds of plant species collected from 20 prefectures in Japan were found to be infected with BBWV-2.
Phytophthora rot of New Zealand spinach Tetragonia teragonoides (Pall.) O. Kuntze occurred in Tokyo Metropolis in 2003. A Phytophthora species isolated from the diseased plants was identified as Phytophthora nicotianae van Breda de Haan. Inoculation tests showed that this fungus was the causal agent of this disease. This is the first report on the disease in Japan.
Leaf spot of ming aralia, Polyscias fruticosa (L.) Harms and geraniumleaf aralia, P. guilfoylei (Bull) L. H. Bailey occurred on Ogasawara (Bonin) Islands in 2002. The pathogens isolated from the diseased plants were identified as Alternaria panax Whetzel. An inoculation test confirmed that this fungus was the causal agent of the disease. This is the first report of this disease in Japan.
Leaf blight of fig-marigold Lampranthus spectabilis (Haw.) N. E. Br., stem and root rot of band plant Vinca major L. form. elegantissima hort. and web blight of Abelia×grandiflora ‘Edward Goucher’ occurred in Tokyo Metropolis in 2003. A Rhizoctonia species isolated from the infected plants was identified as Rhizoctonia solani Kühn. Inoculation tests showed that this fungus was causal agent of these diseases. This is the first report on these diseases in Japan.
Gray mold and leaf blight of Photinia glabra Maxim. occurred in Tokyo Metropolis in 2003. A Botyytis species isolated from the infected plants with gray mold was identified as Botyytis cinerea Persoon: Fries. Inoculation tests showed that this fungus was causal agent of the diseases. This is the first report of gray mold on Photinia in Japan.
Brown leaf spot of Ruscus hypoglossum L. occurred at Hachijo-island of Tokyo Metropolis in 2003. The pathogen from the diseased plant was identified as a species of Rhizopus. An inoculation test confirmed that this fungus was the causal agent of the disease. This is the first report on this disease in Japan.
Rhizoctonia rot of Christmas-bells (Sandersonia aurantiaca Hook) occurred at Hachijo-island of Tokyo Metropolis in 2003. The pathogen from the diseased plant was identified as Rhizoctonia solani AG-4. An inoculation test confirmed that this fungus was the causal agent of the disease.
The performance of some traps (corn trap, funnel trap, reversed funnel trap and SE-trap) baited with synthetic sexual pheromone were compared and examined for their ability to attract the oriental corn borer, Ostrinia furnacalis (Guenee). Consequently, the attraction trend was similar for all traps. The funnel trap attracted many adults, the most of the four kinds of traps examined. It was concluded that the funnel trap can be used effectively for trapping oriental corn borers baited with synthetic sexual pheromone.
Overwintering site of the bean bug, Riptortus clavatus, was evaluated from a choice test in a cage from December 2003 to March 2004. To test which environmental conditions were preferred as an overwintering site, four cages were placed in the field. In each field cage, four types of substrate made of rock, a young tree of Japanese cedar with fallen leaves of Japanese cedar, dead grass weed, or fallen broad leaves were set up. The adults of the bean bug were maintained in the laboratory at 25°C, 10L14D for induction of diapause. In mid December 2003, 193 adult bugs were released in each field cage and adults in the cages were collected March 2004. Numbers of collected bugs differed significantly among the four conditions (Japanese cedar>dead grass weed>fallen broad leaves>rock), suggesting that this species preferred Japanese cedar forest and grass weed as overwintering sites.
The effectiveness of biological control against Liriomyza trifolii (Burgess) by release of the parasitoids, Hemiptarsenus varicornis (Girault), on cherry tomatoes in greenhouses was evaluated. H. varicornis were released 5 times after planting at release rates of 0.33 and 0.16 females per plant in greenhouses from May to June. The density of leafminer larvae at the peak of the occurrence in 0.33 and 0.16 females per plant greenhouses and the control greenhouse were 2.8, 15.9 and 23.6 per leaf, respectively. The density of mines in 0.33 and 0.16 females per plant greenhouses and the control greenhouses were 6.2, 32.2 and 38.0 per leaf, respectively. The percentage of parasitism in 0.33 and 0.16 females per plant greenhouses were 43.7 and 4.8% at 3 weeks after the first release, and were 80.3 and 73.1% at 4 weeks after the first release, respectively. Although H. varicornis was the primary dominant species in the former period, indigenous parasitoids considered hyperparasites to H. varicornis were dominant species in the late period. These results suggest that biological control by H. varicornis against L. trifolii was practically effective on tomatoes in greenhouses.