Green pepper seedlings using peat-moss pots were transplanted to fields in Iwate and Ibaraki Prefectures, and the effect on growth and the occurrence of mosaic disease caused by soil transmission of Pepper mild mottle virus (PMMoV) were examined. There was no big difference in the plant length and the amount of fruits when the seedlings using peat-moss pots and the usual seedlings were compared. The occurrence of mosaic disease two months after transplanting, which is thought to be caused by soil transmission, showed 0% in the transplants of seedlings using peat-moss pots, though 7% in the transplants of usual seedlings. This result indicates that transplanting green pepper seedlings using peat-moss pots is effective to control the soil transmission in fields infested with PMMoV.
The prevention of Pepper mild mottle virus (PMMoV) contact transmission in green pepper was examined using scissors with automatic disinfectant sprayer that automatically washes blades according to the movement of the blades. When blades infested with PMMoV were washed using mycelia extract of shiitake mushrooms and skim milk solution as a cleaning solution, infection of PMMoV to healthy plants was suppressed. Therefore, these scissors with automatic sprayer are effective to prevent transmission of PMMoV under work with green pepper.
Verticillium wilt of Cirsium japonicum (Thunb.) DC. and Tagetes evecta L. occurred in Tokyo Metropolis in 1998. The causal fungus isolated from the diseased plants was identified as Verticillium dahliae Klebahn. Inoculation tests showed that this fungus was the causal agent of these diseases. This is the firstreport on the diseases in Japan.
Cylindrocarpon root rot of Arbutus unedo L. and Ardisia japonica (Thunb.) Blume occurred in Tokyo Metropolis in 2003. The causal fungus isolated from the diseased plants was identified as Cylindrocarpon destructans (Zinssmeister) Scholten. Inoculation tests showed that this fungus was the causal agent of these diseases. This is the firstreport on the diseases in Japan.
Anthracnose of Arbutus unedo L. occurred in Tokyo Metropolis in 2003. The causal fungus isolated from the diseased plants was identified as Colletotrichum gloeosporioides (Penzig) Penzig & Saccardo. Inoculation tests showed that this fungus was the causal agent of this disease. This is the first report on the disease in Japan.
Only one male adult of Riptortus clavatus and no adults of Piezodorus hybneri, both of which are the most important pests of soybean, were found among the leaf litter samples collected at a copse during the winter season for 14 years to estimate the overwintering adult density of Plautia crossota stali, one of the most important pests of tree fruits. Of the 483 bugs found, 339, 70 (fifith instar), 31 and 19 were P. crossota stali, Poecilocoris lewisi, Acanthosoma denticauda and Sastragala esakii, respectively. The result strongly suggested that the main overwintering site of the two soybean pests might be different from that of P. crossota stali, presumably the soybean pests overwinter at a forest edge or near the roots of dry Japanese pampas grass.
Scepticus griseus Roelofs and S. uniformis Kôno are pests of carrots, burdocks, welsh onions, and peanut crops in Chiba Prefecture. Overwintering adults had a low threshold temperature of development of 1.1°C, and a total effective temperature of 112 degree during the preoviposition period. Overwintered adults produced eggs from April through August. Callow adults produced eggs in September, and wintered in October.
The effects of temperature on the flight activity and dispersal of the American serpentine leafminer, Liriomyza trifolii (Burgess) were evaluated by laboratory experiments and release experiment of adults in a greenhouse. In the laboratory experiments, catch rates of L. trifolii adults by yellow sticky traps at the conditions of 15, 20, 25, and 30°C increased with temperature, and catch rates at 15°C hardly increased with time after release. Catch rates of females were repressed when a host leaf was given with the adults compared to non-leaf conditions, however, the catch rates of males were not affected by a host leaf. L. trifolii adults were released in the center of a greenhouse in both spring season when daily average temperatures were about 15°C, and summer season when daily temperatures were 30°C. The numbers of the adults on each host plant pot arrayed in a lattice on the greenhouse ground were counted during six days after release, and distribution and spatial pattern of the adults were investigated by aggregation index of CA and the distance from release point to host plants. In the spring season experiment, the adults and eggs oviposited indicated aggregated distribution, and in the summer season it indicated uniform distribution. These results suggested that temperature in a greenhouse affects dispersal and spatial pattern of L. trifolii.
Exotic phytoseiid mite, Typhlodromus occidentalis from New Zealand, was released into apple orchards at the Nagano Fruit Tree Experiment Station in 1990 and 1991 for the control of spider mites. We surveyed species composition of phytoseiid mites in the orchards after 13 years of its release to evaluate the ecological effects on native phytoseiid mites. No T. occidentalis was found at all and the result was the same as that obtained in Akita and Aomori Prefectures in 2002-2003. We speculate that the introduced T. occidentalis had scarcely any significant ecological effects on native phytoseiid mite species except for only a short time just after its release. Neoseiulus californicus appeared to be highly dominant in these orchards. Furthermore, as there are recently native and alien strains of N. californicus in Japan, it is important to investigate intra- and inter-specific relationships with other native phytoseiid mites.
The effects of several insecticides on the predacious natural enemy, Pseudoscymnus hareja (Weise), of the white peach scale, Pseudaulacaspis pentagona (Targioni), were evaluated by laboratory experiments. The larvae of P. hareja for tests were collected from tea fields, these insects were contacted with tea branches dipped in insecticides diluted with water to ordinary use concentration. Imidacloprid and bifenthrin were very harmful and killed all larvae, acetamiprid and acephate were moderately harmful and their emergence rates of treated larvae were 43.7% and 37.5%, respectively. Fenpyroximate+buprofezin mixture, methidathion and chlorphenapyr were almost safe and their emergence rates of treated larvae were from 70.6% to 86.2%. Pyriproxyfen was safe to the larvae and all became to pupae, however, it strongly prevented emergence.