The production of vegetables in greenhouses in Japan is characterized by an intensive use of pesticides. It is necessary to change chemical control to integrated pest management for avoiding imsecticide resistance problems. Possible ways to reduce pesticide use are discussed. A method of prevention of aphid invasion into the greenhouse and reduction of aphid density on seedlings has been devised for integrated pest control of strawberry grown in the greenhouse.
Reginal clasification of Ibaraki prefecture was carried out for previse forecasting by Principal Component Analysis of degrees of leaf blast and panicle blast. The degree in occurrence of leaf blast was used from data in late July and panicle blast in late August or early September in 1977-1989 at 150 stations set up on the paddy field, which are the monitoring place of pests and insects. Leaf blast was classified into 7 area, severely occurence area distributed from the north to east in Ibaraki Prefecture. Leaf Blast occured severely in nouth area in 1984, and the east area occured in 1977. Panicle blast was classified into 4 area. Disribute pattern in panicle was not equaled to that of leaf blast. But area of severely occurrence of leaf blast was that of severely occurrence of panicle blast.
At Ogawa, Shimodate, Ibaraki in 1990, incidence of barley yellow mosaic virus (BaYMV) was monitored in the two-rowed barley cultivar “Misato Golden” whitch is resistant to BaYMV strain I and II. In 11 fields out of 48 planted for “Misato Golden”, BaYMV infection was noticed.
Irrigation and mulch-removal treatments as practical means to control russet scab of potato caused by Streptomyces cheloniumii were evaluated in field experiments. These treatments reduced the damage of the disease. Removing mulch in early May followed by irrigating from early May to early June resulted in the most effective control. On the other hand, to irrigate from mid May to early June was proved to be the best measure in the non-mulch treatment.
In Kanagawa Prefecture, the virus disease of tomato showing systemic necrotic symptoms was rather widely distributed in 1987-1988. Potatovirus Y-T (PVY-T) was isolated from those tomato plants. In some of those plants, PVY-O was also isolated. Inoculation of PVY-T alone to tomato plants induced systemic necrosis.
Dot-immunobinding assay (DIA) was useful for detecting Onion yellow dwarf potyvirus (OYDV) and Garlic latent carlavirus (GLV) from infected Welsh onions. The optimum concentrations of anti-OYDV and anti-GLV γ-globulins were 0.125 and 0.25μg/ml, respectively. Under these conditions, the reaction end points of crude extracts of OYDV and GLV infected leaves were 1600-fold and 1280-fold, respectively, Viral antigen (VA) solutions were easily prepared from infected leaves as follows: The epidermis of infected leaves were peeled with razor blades. Two μl of buffer were put on the wound and mixed with the sap. The mixture was used as the VA solution. The VAs of OYDV and GLV, which were adhered to cellulose nitrate membrane, could be stored for 6 months in a desiccator and could be mailed without reduction of the color intensity of the DIA.
Infectivity of 18 cucumber mosaic virus isolates from cucumber plants was tested. Two of the eighteen isolates were shown severe symptom on cucumber plant. We considered that two isolates were suitable to investigate cross protection of attenuated virus.
Tomato seedlings were cutted off the root, and were inoculated by dipping into spore suspensions of avirulent Fusarium oxysporum. After inoculated seedlings were transplanted for roots in the disinfected soil for one week, they were transplanted in Fusarium contaminated fields. The development in wilting symptom on seedlings with pre-inoculated were weakened equally compared with uninoculated plants.
Pythium blackleg of Geranium occurred in Saitama Prefecture in 1989. Two Pythium species were isolated from damaged plants and identified as P. aphanidermatum and P. splendens. An inoculation experiment showed that those fungi were the causal agents of the disease.