Damping-off of leaf lettuce (Lactuca sativa var. crispa) occurred in Ibaraki Prefecture in September, 2013. The causal agent was identified as Pythium aphanidermatum on the basis of morphology, suitable growth temperature and ribosomal DNA internal transcribed spacer (rDNA-ITS) region. We propose that P. aphanidermatum should be added to the pathogens of damping-off of lettuce. The degree of virulence, rot and wilt of leaves, and growth inhibition of plant, was more remarkable at relatively high temperature conditions.
In June 2012, a foot rot disease of nasturtium (Tropaeolum majus L.) cultivated in Kamakura, Kanagawa was found for the first time in Japan. The causal fungus was identified as Rhizoctonia solani AG-4 HG-I based on morphology and PCR analysis with specific primers. We propose to call the new disease “Kabugusare-byo” in Japanese.
The use of antifoam reagents in enzyme-linked immunosorbent assay (ELISA) was examined to reduce troubles during the assay for plant virus detection. Antifoams, SI and PE-L were added to a washing buffer (WB), phosphate buffered saline with Tween® 20 (PBST) or a chromogenic substrate, p-nitrophenylphosphate (CS) solution for alkaline phosphatase. The absorbance values for Tomato spotted wilt virus, Zucchini yellow mosaic virus and Rice stripe virus (RSV) measured no difference between PBST with/without antifoams (0.1%) used as WB although those using CS containing antifoams showed higher values. PBST with SI was also effective for the simplified procedure for extraction of RSV. In conclusion, PBST with an antifoam SI is effective to improve operation efficiencies of ELISA.
We evaluated the effect of the insecticides, pyrifluquinazon and pymetrozine, on the predatory mirid bug, Nesidiocoris tenuis (Reuter). The mortality of N. tenuis was not significantly different between both of the insecticides and control by two methods, insect-dip and tomato leaf-dip. In an experiment of insecticide application on tomatoes in a greenhouse, the density of N. tenuis in the pyrifluquinazon plot was significantly lower than in the control plot. No significant difference was shown in the pymetrozine plot compared to the control plot. In an experiment of insecticide application to N. tenuis on a tomato seedling in a cage under laboratory conditions, numbers of N. tenuis remaining on tomato in the pyrifluquinazon plot was significantly smaller than in the control plot although the number recovered over time. No significant difference was shown in the pymetrozine plot from the control plot. Mortality of N. tenuis was not significantly different between the treatment and the control plot. A similar result was shown in an experiment of released insects to the insecticide applied tomato seedling in a cage. These results indicate that pyrifluquinazon suppresses the density of N. tenuis by inhibiting its orientation behavior although both of the insecticides, pyrifluquinazon and pymetrozine, show little direct activation on the killing activity of N. tenuis.
We examined the effect of insecticides on an important pest, Thrips palmi Karny, collected in Shizuoka Prefecture from three melon greenhouses in 2013 and ten melon greenhouses in 2015. Female adults were examined using a kidney bean leaf dipping method under laboratory conditions. The mortalities of T. palmi populations examined in 2013 were high with emamectin benzoate and pyridalyl on all populations, and were high with spinosad and spinetoram except for one population. However, mortality levels were low with cypermethrin, four neonicotinoid insecticides and abamectin on all populations. The mortalities examined in 2015 were at high levels with nitenpyram on two of ten populations, whereas at low levels with dinotefuran, spinosad, spinetoram, emamectin benzoate and pyridalyl, with a few exceptions.
We tested the toxicity of 11 pesticides on the ladybird beetle Chilocorus kuwanae Silvestri, a predator of the white peach scale Pseudaulacaspis pentagona (Targioni) in tea fields by a contact method using tea branches. The organophosphate insecticide-methidathion was seriously harmful to the larvae and moderately harmful to the adults, the neonicotinoid insecticide-dinotefuran, pyrethroids insectiside-bifenthrin, and diafenthiuron were moderately harmful to the larvae. Cyantraniliprole, spinetoram, pyflubumide, fenpyroximatebuprofezin mixer, flufenoxuron and tolfenpyrad were not harmful to the larvae, although flufenoxuron might affect the emergence. Fenpyroximate-buprofezin mixer and pyrifluquinazon were not harmful to the adults.
The influence of weed management on the population of predacious arthropods: ants, arboreal and wandering spiders, ground beetles, and phytoseiid mites, was researched in apple orchards. As a result, the population of wandering and arboreal spiders was significantly increased in a condition of complete ground cover with natural weeds, compared to weeds partially controlled by herbicides only around apple trunks and stakes, and controlled by herbicides on the entire ground surface.
A simple method for rearing native predatory mites in greenhouses by growers themselves may contribute to biological control against spider mites and/or small pest insects. We investigated the rearing efficiency of a native predatory mite (Neoseiulus womersleyi) on potted kidney bean plants infested with two-spotted spider mites Tetranychus urticae or T. pueraricola in a greenhouse. We obtained many predator individuals from T. urticae-infested bean plants, when offering them additional prey in the experiments; obtaining 2443 individuals from 5 female founders after 24 days, and 300 individuals from 2 females after 28 days. Without additional prey, we could obtain 223 individuals from one female on T. urticae-infested bean plants after 28 days, and 37 individuals from one female on T. pueraricola-infested bean plants after 18 days. These results indicated that kidney bean plants infested with either prey mite are potentially useful for simple rearing of N. womersleyi in a greenhouse.