Pseudomonas fluorescens FPH9601 and FPT9601 are commercial endophytic bacteria in Japan (Taki Chemical), which were originally isolated from tomato rhizosphere. The endophytic bacteria have also shown to act as a biocontrol agent of soilborne diseases such as bacterial wilts of tomato, eggplant and green pepper caused by Ralstonia solanacearum. The other endophytic bacterial strains which were isolated from Chinese cabbage and lettuce suppressed clubroot diseases of Chinese cabbage caused by Plasmodiophora brassicae, and melon necrotic spot and lettuce big vein whose causal agents were transmitted by Olpidium bornovanus and O. virulentus, respectively. We have developed a new technology which enables to coat seeds with endophytic bacteria. This technology has been proved to be useful for the control of lettuce big vein disease. This epoch-making technology could allow to prevent diseases without depending too much on chemicals, and to achieve eco-friendly and safe agriculture with less labor and lower cost than the current method to disinfect the field.

Eyespot disease of wheat occurred in previously pathogen-free-soil that was even slightly mixed with infested soil. When wheat was grown in a field newly converted from a paddy field located next to a diseased continuous wheat-cropping field, eyespot disease was found during the first wheat growing season, and disease occurrence in the second season was almost equal to that in the diseased continuous wheat-cropping field. This suggests that the eyespot pathogen easily invades and establishes itself in non-infested fields.

Eyespot disease severity was higher when wheat stem number/m² was greater, which resulted from higher seeding rates and earlier sowing dates. This indicated that disease losses could be reduced by proper sowing and nitrogen application to prevent excessive tillering in wheat.

A total of 108 wheat varieties collected from Japan and other countries were examined for resistance to eyespot disease. All of the varieties bred in Japan were susceptible, whereas four foreign varieties, VPM-1, Madsen, Cappelle-Desprez, and Cerco, showed resistance, and could be used as parents in the development of resistant varieties in Hokkaido. The difference in susceptibility of wheat varieties to eyespot disease in our test was clearer than that in the United States. The results suggest that our method is useful for testing wheat resistance to eyespot.

Between November 2017 and March 2018, leaf rot, basal petiole rot, and damping-off of several leafy vegetables [Chinese mustard, potherb mustard, norabona (rape), yukina, Chinese cabbage, komatsuna, chingensai, and spinach] were found in four greenhouses in Hokkaido, Japan. Twelve isolates were obtained from each symptom. Of these, 11 isolates were identified as belonging to the Rhizoctonia solani anastomosis group (AG)-2-1 Subset1. The one remaining isolate was identified as R. solani AG-2-1 Subset2. Original symptoms were reproduced on almost all plants that were inoculated with these isolates. This is the first report of diseases caused by R. solani AG-2-1 in three crops (chingensai, rape, and spinach) in Hokkaido and in two crops (Chinese mustard and yukina) in Japan.

The efficacy of drip irrigation of two fungicides in controlling Fusarium wilt caused by Fusarium oxysporum f. sp. cepae in Welsh onion before transplanting was evaluated in the fields from 2014 to 2018.Several trials were conducted for each fungicide, and the data were analyzed by meta-analysis. An integrated risk ratio (the ratio of incidence on treated plants to incidence on non-treated plants) after treatment with mandestrobin flowable was 0.11 (95% confidence interval 0.06–0.21), indicating that the fungicide was effective against this disease. However, an integrated risk ratio after treatment with triflumizole wettable powder was 0.67 (95% confidence interval 0.41–1.10), indicating that the fungicide was not effective against this disease. The effect of fungicide application on the growth of Welsh onion was also evaluated. In three-year trials from 2015 to 2017, application of mandestrobin flowable inhibited plant growth in 2017.

During our routine disease surveys of garlic in Aomori Prefecture, Japan, leaf blight was frequently observed. An isolate was obtained from a diseased leaf in 2017. Conidiophores of the isolate were 15–145 μm long and 4.3–6.5 μm wide, with swellings at the distal ends. Conidia were 25–67×14–28 μm in size, with a length to breadth ratio of 1.20–3.04 (mean 2.30), and were constricted at 1–3 major transverse septa. The isolate also produced the perfect state, i.e., pseudothecia, asci, and ascospores. These morphological characteristics were similar to those of Stemphylium sp. Subgroup C2. We also conducted molecular phylogenetic analysis based on four loci (the rDNA-ITS region, EF-1α gene, GPD gene, and vmaA-vpsA gene). The isolate was classified into Subgroup C2 in the phylogenetic tree. Based on both morphology and phylogeny, the isolate was identified as Stemphylium sp. Subgroup C2. We confirmed the pathogenicity of the isolate toward garlic in an inoculation test. Leaf blight in garlic caused by Stemphylium sp. Subgroup C2 has not been reported in Japan; therefore, we propose to include it as one of the pathogens of the disease.

To evaluate the potential enhancement of establishment speed and abundance of the generalist zoo­phytophagous natural enemy, Nesidiocoris tenuis (Hemiptera: Miridae) on tomato (Solanum lycopersicum (Solanales: Solanaceae)) under greenhouse conditions, we compared the effect of release site on tomato crop and an alternative host plant (garden verbena, Verbena×hybrida variants (Lamiales: Verbenaceae) (V.×hybrida cv. Tapian in 2017, V.×hybrida cv. Hanatemari-aya in 2018), which is a common release site. We monitored baseline prey populations of greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) on tomato plants without natural enemy release in 2016, and with release in 2017 and 2018. The experiment consisted of two separate greenhouses with both the host plants and 15 individuals of N. tenuis were released three times on the tomato crop in one of the greenhouses and on the garden verbena in the other greenhouse. Based on this experiment, we were able to draw several conclusions. Approximately two weeks after initial release, N. tenuis individuals were initially observed on the garden verbena in both greenhouses, and subsequently on the tomato plants. Once N. tenuis individuals were observed on tomato plants for aproximately 40 days after release, the number of observed individuals on tomato plants and garden verbena showed a similar seasonal prevalence. This seasonal prevalence did not differ regardless of release site for both years. The absolute number of N. tenuis individuals observed on both the tomato and garden verbena was higher when N. tenius was released on garden verbena than that on tomato plants in 2017. Notably, after release in 2017, numerous ants [Lasius hayashi (Hymenoptera: Formicidae)] were observed in the vicinity garden verbena plants, and they seemed to carry N. tenuis nymphs around. In 2018, the greenhouses were switched to reduce environmental variation, and N. tenuis individuals were relesased on the tomato and garden verbena. However, just before release, packages of granular ant insecticide were placed in the greenhouses. The number of N. tenuis individuals observed in both greenhouses in 2018 was very similar between the tomato and garden verbena and also showed a similar seasonal prevalence. These results indicate that N. tenuis on tomato plants provides little to no enhancement of establishment speed or population size. The poupulation of greenhouse whiteflies in the greenhouses remained low during the growing season of the tomato plant, suggesting that N. tenuis is an effective biological control agent of greenhouse whiteflies on tomato plants although the experimental location is not a natural distributing area of the species.