The damage caused by anthracnose is a problem in organic tea fields in Shizuoka Prefecture, Japan, highlighting the need to develop an effective method for anthracnose control. Therefore, we developed a pest-cleaning machine designed for pest control in organic tea fields. This machine can remove a certain number of anthracnose-diseased leaves from the canopy of tea plants by blowing air while simultaneously spraying agrochemicals, such as copper fungicides. Therefore, we determined which treatment schedule using the machine was effective for controlling anthracnose in a tea field at the Tea Science Research Center, Shizuoka Prefectural Research Institute of Agriculture and Forestry (Kikugawa City, Shizuoka Prefecture). In machine-treated plots (without simultaneous copper treatment) before or during the sprouting period of each tea season, the preventive value against anthracnose before the plucking time in the second tea season and during the third tea season ranged from 42.9–53.4, and the number of anthracnose-diseased leaves was reduced by nearly half compared to untreated plots. Additional machine treatment before plucking or simultaneous copper treatment did not significantly affect the number of anthracnose-diseased leaves. We then evaluated the control effect of the machine on anthracnose in local organic tea fields in the two regions. At an organic tea field in Shimada City, Shizuoka Prefecture, the number of anthracnose-diseased leaves was lower in the machine-treated plots (without simultaneous copper treatment) during the sprouting period of each tea season and before plucking in autumn tea season compared to untreated plots (the preventive value: 32.3–47.0). At organic tea fields in Numazu City, Shizuoka Prefecture, the number of anthracnose-diseased leaves was also lower in the machine-treated plot (without simultaneous copper treatment) during the sprouting period of autumn shoots after pruning and before plucking in the autumn tea season compared to untreated plots (the preventive value: 53.1–83.3). This study revealed that the pest-cleaning machine treatment can suppress anthracnose, highlighting its usefulness and significance in controlling this disease in organic tea fields.

This study examined the toxicity of five insecticides used to control overwintering adults of the brown rice stink bug Niphe elongata, an agricultural pest insect causes sterile rice. Overwintering adults of N. elongata were collected from three sites in southern Shiga Prefecture in July 2024. The effectiveness (corrected mortality) of each insecticide was evaluated using the adult-dipping method, complemented by a Bayesian model to control for sex-based differences in insecticide response. Results indicate that ethiprole, etofenprox, dinotefuran, and sulfoxaflor (each at 100 ppm) were highly toxic, achieving over 80% corrected mortality within 24 hours after exposure. Flupyrimin (100 ppm) showed lower toxicity than other insecticides in two strains. In all strains, it was also less toxic to females than in to males. Some adults initially affected by flupyrimin exhibited recovery, corrected mortality at 72 hours after exposure was lower than at 24 hours.

We evaluated the efficacy of warm water disinfection at controlling sesame bacterial leaf spot caused by Pseudomonas syringae pv. sesami. Warm water treatment of seeds at 50°C for 5 to 20 min and 55°C for 5 to 15 min was highly effective in the young seedlings and in the field test. Treatment at 55°C reduced germination vigor but not rate. This suggests that treatment at 50°C is preferable for practical use.

In this study, we aimed to investigate the relationship between the percentage of rice stripe diseased plants and the population of small brown planthopper (Laodelphax striatellus) in paddy rice fields. Additionally, we sought to examine the abundance of L. striatellus in wheat fields and the percentage of Rice stripe tenuivirus (RSV)-carrying L. striatellus in wheat fields in the Chuen region of Shizuoka Prefecture, central Japan, from 2001 to 2017. The results revealed a positive correlation between the abundance of L. striatellus in a rice field and the incidence of rice stripe disease in plants in the following year. However, no correlation was observed between the prevalence of rice stripe disease in plants and the abundance of L. striatellus in paddy rice fields in the same year, the proportion of L. striatellus in wheat fields, the proportion of RSV-carrying L. striatellus in wheat fields, or the abundance of RSV-carrying L. striatellus in wheat fields.

When brine shrimp cysts Artemia salina Linnaeus, in a hydrated state with their shells intact (expected to absorb water from strawberry plants and soil when scattered at the base of the plants in the field), were provided, the lifetime fecundity and average longevity of a predatory thrips, Haplothrips brevitubus (Karny) increased compared to when they were not provided. No phytotoxic effect on strawberries were observed even when an excessive amount of brine shrimp cysts was sprayed at the base of the strawberry plants. Experimental field trials showed that spraying brine shrimp cysts at the base of strawberry plants in combination with the release of the predatory thrips adults increased the initial number of established adults and the number of next-generation larvae of the predatory thrips. Similar trends were confirmed in the trials in growers’ fields. The spraying of brine shrimp cysts had no negative effect on the dispersal speed between plants or the distribution patterns of the predatory thrips on flowers and fruits where pest thrips such as Frankliniella intonsa (Trybom) inhabits. The spatial overlap of adult-immatures distributions (Iwao’s ω index) indicated that spraying of brine shrimp cysts could lead to more widespread adult dispersal.

Prevalent mode of reproduction of wild populations of Thrips nigropilosus Uzel was examined in Wakkanai City, Japan. Furthermore, reproductive schedule, fecundity, and tertiary sex ratio were compared between thelytokous and arrhenotokous T. nigropilosus. Percentages of thelytokous adults in adult females of the Wakkanai population were 4.0% in October 1992, and about 0.8% in July 1994. Significant differences between thelytokous and arrhenotokous races were not observed in the duration of pre-ovarial maturation, oviposition periods and longevities of adult females at the 18°C and 15L-9D condition. The mean numbers of eggs deposited by thelytokous and arrhenotokous females were ca.63 and ca.142 at the same condition, respectively. The hatchabilities of eggs deposited by thelytokous and arrhenotokous females were not different from each other. The tertiary sex ratio (% male) from once-mated arrhenotokous females was about 23.6%. Net reproductive rate of the once-mated arrhenotokous female tended to be higher than that of the thelytokous female, while intrinsic rates of natural increase of them were not conspicuously different from each other.

We evaluated the control effect of four commercial natural enemy species against thrips, mainly Frankliniella intonsa (Trybom), and the suppression of thrips-mediated fruit damage after the spring season in forcing strawberry (Fragaria × ananassa Duch.) cultivation for three years from 2022 to 2024 in Shizuoka Prefecture, Japan. In 2022, Amblydromalus limonicus (Garman and McGregor) (50,000 individuals/10 a) and Haplothrips brevitubus (Karny) (15,000 individuals/10 a) were released. A. limonicus showed no effectiveness against thrips, and this natural enemy was not found in flowers, which are the main habitat of thrips. H. brevitubus appeared to suppress thrips larvae. In 2023 and 2024, each natural enemy species was released three times at one-month intervals. All natural enemy species suppressed thrips; however, the rate of fruit damage varied depending on the species. In 2023, the ratio of thrips-damaged fruits to total harvested fruits was significantly lower, in the following order: Amblyseius cucumeris (Oudemans) (700,000 individuals/10 a) < A. cucumeris (350,000 individuals/10 a) = Amblyseius swirskii Athias-Henriot (50,000 individuals/10 a). The rate in 2024 was significantly lower, and in the following order: A. cucumeris (350,000 individuals/10 a) < A. swirskii (50,000 individuals/10 a) = H. brevitubus (15,000 individuals/10 a). These results suggest that A. cucumeris provides the best control against thrips on strawberries. This effect may be primarily attributed to the high release rate of A. cucumeris. However, it is necessary to use other control measures after late May because even A. cucumeris could not suppress the increase in damaged fruits after this period.

The sensitivity of Beauveria bassiana strain GHA, an active component of biocontrol agents, against chemical fungicides, bactericides, and insecticides was investigated using yeast extract, peptone, and agar (YPA) media as a low-nutrient medium. Both colonies derived from conidia and colony expansion were inhibited by multi-site activity inhibitors, mancozeb, thiuram, propineb, and captan, and three sterol biosynthesis inhibitors. Additionally, benomyl, azoxystrobin, fludioxonil, and fluazinum inhibit GHA growth. TPN inhibited colony formation from conidia, but the negative effect on colony expansion of the GHA strain was small. Acaricide pyrimidifen inhibited colony expansion. When mixed with B. bassiana agents, these chemicals may inhibit biocontrol activity. However, their inhibitory effects on GHA formulations in plants remain unclear.

The sensitivity of Beauveria bassiana strain GHA, an active ingredient in biocontrol agents, to chemical fungi and bactericides in plant leaves was investigated. Conidia of the GHA strain were mixed with 40 chemical agents registered in Japan and inoculated onto cucumber leaves. After a week of incubation, the rise and fall of the colony-forming units (CFUs) of the strain were measured. Many multisite activity inhibitors and sterol biosynthesis inhibitors decreased the CFUs of the strain. Fludioxonil, fluazinum, cymoxanil, fenexamide, benomyl, amisulbrom, mandipropamid, pyriofenone, polyoxins, fosetyl, flutianil, and kasugamycin decreased strain growth, in addition to sodium or potassium hydrogen carbonate in organic agricultural materials. When these chemicals are mixed to Beauveria bioagents, effects of the bioagents may be inhibited.

To investigate the influence of infestation by and number of rice stink bug, Niphe elongata (Heteroptera: Pentatomidae) on rice grain sterility, we released adult bugs at the rate of 0.125, 0.25, or 0.5 per rice panicle, at 0, 7, or 14 days after heading to feed for 7 days. Degree of grain growth decreased with the number of bugs released and with earlier release. Estimated grain sterility was 21.1%, 15.4% and 9.6% when bugs were released on the day, 7 days and 14 days after heading at a rate of one bug per plant, respectively. These results suggest that grain sterility increases with the number of adults, in the early ripening period, but it is less likely to increase with the number of adults in the mid-ripening period.

To investigate the effect of daytime lighting with red LED lights to suppress thrips’ infestation in the chrysanthemum plants grown in greenhouses, we conducted experiments using this strategy, in the fall 2021 and in the summer 2022.

Compared with the treatment without daytime lighting, the treatment with daytime lighting slightly reduced the infestation density of thrips as well as the number of damaged leaves in chrysanthemum plants. The same effect was observed with exposure to daytime lighting on the side of the greenhouse.

Furthermore, a survey of adult thrips trapped inside and outside the facility using yellow sticky traps revealed that daytime lighting was effective in preventing the intrusion of thrips into the facility from the outside in both the treatment areas.

However, exposure to daytime lighting markedly delayed the flowering in the chrysanthemum cultivar “IwanoHakusen”. Therefore, caution is required regarding the use of the treatment, and further investigation will be conducted in future tests.

During fungicide sensitivity tests conducted on Mycovellosiella nattrassii isolates obtained from eggplants in Osaka Prefecture, Japan, between 2012 and 2018, variations in sensitivity among different fungicides were observed. Least isolates exhibited low sensitivity to azoxystrobin (QoI) and penthiopyrad (SDHI) from 2014 to 2022. In contrast, the proportion of isolates low sensitive to triflumizole (DMI) was high during the same period. In 2024, a majority of isolates demonstrated reduced sensitivity to triflumizole, fenarimol (DMI), myclobutanil (DMI), azoxystrobin, kresoxim-methyl (QoI), penthiopyrad, and isopyrazam (SDHI). However, they remained sensitive to difenoconazole (DMI), pyribencarb (QoI), pyraziflumid (SDHI), and boscalid (SDHI). These results indicate that M. nattrassii isolates in Osaka Prefecture are predominantly characterized by reduced sensitivity to triflumizole, azoxystrobin, penthiopyrad, and isopyrazam. Furthermore, an analysis of fungicide application history revealed that fungicides with reduced efficacy were frequently applied across multiple fields. To mitigate the risk of developing fungicide-resistant M. nattrassii isolates, it is crucial to incorporate fungicides with multi-site modes of action, such as chlorothalonil and iminoctadine albesilate, which are considered to have a low resistance risk, for preventive management. Additionally, in cases where fungicide-resistant isolates are detected, it is essential to integrate into the rotation fungicides that have not yet exhibited a decline in efficacy.

To evaluate the impacts of the alien grasshopper Atractomorpha sinensis on agricultural crops in Japan, field surveys and laboratory experiments were conducted, and the results were compared with those obtained from the native grasshopper A. lata. The seasonal occurrences of A. sinensis and A. lata were recorded in 2022 and 2024 in Osaka Prefecture. The adult population density of A. sinensis exhibited two peaks, one in early summer and another in autumn, while A. lata showed only a single autumn peak. In addition, the abundance of both species was compared at seven sites, each at different altitudes, in southern Osaka Prefecture in 2017, 2022 and 2024. The distribution of A. sinensis was observed to expand annually from lower to higher altitude sites, and once it invaded a site, that site became dominated by A. sinensis within a few years. The flight ability of A. sinensis was markedly higher than reported previously, which is likely a key factor underlying the rapid spread of this species in Japan. Mating experiments revealed frequent interspecific mating. Given that the adult seasons of both species overlapped in autumn, such interactions likely occur in the field and may negatively affect A. lata. The findings suggest that range expansion in A. sinensis has resulted in the displacement of A. lata, and that agricultural crops may be damaged at unexpected times because of the ability of A. sinensis to produce two generations a year.

The potential pathogenic risk of Aphanomyces cochlioides originating from hydroponically grown quinoa on soil-cultivated plants was evaluated. A. cochlioides is widely recognized as one of the causal agents of sugar beets under soil conditions. However, the pathogenicity of the A. cochlioides strain isolated from quinoa in hydroponic conditions on soil-cultivated plants has not been studied. Therefore, the pathogenicity of A. cochlioides on quinoa and sugar beets under soil conditions was confirmed through pot inoculation tests. The results of the inoculation tests demonstrated that the A. cochlioides strain originating from hydroponically grown quinoa can cause severe damping-off of quinoa and sugar beets under soil conditions. The present study confirmed that hydroponic-origin A. cochlioides can act not only under hydroponic conditions but also soil conditions.

Persimmon (Diospyros kaki Thunb.) anthracnose is a serious plant disease caused by Colletotrichum horii B.S. Weir & P.R. Johnston and other closely related species. Sterol demethylation inhibitor (DMI) fungicides are effective against C. horii. Difenoconazole is a systemic fungicide that belongs to the DMI fungicides. In this study, we investigated the sensitivity of C. horii isolates collected from six commercial persimmon orchards in Wakayama Prefecture to difenoconazole. The sensitivity to difenoconazole was evaluated using both a medium test and a bioassay analysis. The medium test results revealed that the EC₅₀ values of difenoconazole ranged from 0.002 ppm to 54.54 ppm. The bioassay analysis indicated that C. horii isolates exhibiting EC₅₀ values of 1 ppm or higher in the medium test were resistant to difenoconazole. The results demonstrated the possibility of the presence of DMI-resistant C. horii on persimmons.

Anthracnose is the most important disease of tea caused by Discula theae-sinensis (I. Miyake) Moriwaki & Toy. Sato (Dts). The most widely planted tea cultivar ‘Yabukita’ is susceptible to anthracnose and is important to the establishment of an efficient technique to control the disease. In this study, we attempted quantitative detection of Dts by real-time quantitative PCR (qPCR) for use in epidemiological studies of this pathogen. We designed Dts-specific primers based on the 28S ribosomal RNA gene sequence and assessed their specificity. We confirmed the high specificity of the primers because no amplification was observed for Dts related species or other major tea-pathogenic fungi. We used DNA extracted from serial dilutions of a conidial suspension as the template to generate a calibration curve and obtained a calibration curve with high linearity in the range of approximately 2 × 10² to 2 × 10⁷ conidia/mL. We applied the qPCR method to quantify Dts in ground leaf disks taken from diseased and symptomless tea leaves. Use of this method to quantify Dts conidial dispersal at each developmental stage of tea will assist in determining the optimum timing for control of anthracnose.

In April 2023, soft rot symptoms were observed in the stem of a melon grown in a greenhouse in Shiga prefecture, Japan. Two days after inoculation of bacteria isolated from the diseased stem into the stem of melon seedlings, soft rot symptoms were observed. A target fragment was amplified from the isolated bacteria by PCR specific to Pectobacterium brasiliense. Because multilocus sequence analysis (MLSA) based on concatenated dnaX, leuS, and recA gene sequences shows the isolate and reisolates from inoculated seedlings grouped with the P. brasiliense clade, the isolate was identified as P. brasiliense. This report is the first of melon disease caused by P. brasiliense in Japan.

Thirty isolates of Cercospora chrysanthemi were collected from garland chrysanthemum fields in Osaka Prefecture and their sensitivity to benomyl and azoxystrobin (QoI) was evaluated. For benomyl, 83% and 8% of the isolates collected in 2016–2017 and 2021–2023, respectively, were resistant. For azoxystrobin, 100% and 50% of the isolates collected in 2016–2017 and 2021–2023, respectively, were resistant. The QoI sensitivity may have been influenced by its application to another disease.

Generally, when testing acaricide susceptibility of spider mites on horticultural crops, populations collected from multiple sites and locations within the same greenhouse are mixed based on the assumption that no difference in genetic diversity and acaricide susceptibility between populations exists. However, the magnitude of the difference in acaricide susceptibility between spider mite populations in the same greenhouse has not been investigated. This study compared the susceptibility of two-spotted spider mite Tetranychus urticae Koch (green form) populations collected from three sites at each location in a single rose greenhouse to different acaricides. For all acaricides, the maximum LC₅₀ values were obtained in populations collected from the northwest of the greenhouse and the base of rose plants. In addition, differences in LC₅₀ values were observed for amitraz EC between collection sites, with maximum differences of 124.6-fold at 24 h post-treatment. These results suggest that local subpopulations develop acaricide resistance, even within a single greenhouse and rose plant. They also vary widely in acaricide susceptibility.

To study the relationship between temperature and occurrence (annual total) of the common cutworm, Spodoptera litura Fabricius, the results of pheromone trap surveys conducted over the past 40 years (1985–2024) by the Mie Prefectural Plant Protection Office were analyzed. A positive correlation (r = 0.68) was found between the average temperature from April to November and total catch number, with hotter years tending to have a higher occurrence. When the results were subdivided by decade, variation became progressively smaller, and the correlation over the last 20 years was higher (r = 0.83).

The effects of insecticides on red-banded thrips, Selenothrips rubrocinctus (Giard) collected from sweetgum, were evaluated. Among the eleven insecticides tested on adults using the maple-tree-leaf dipping method, fenitrothion, acetamiprid, clothianidin, spinetoram, emamectin benzoate, chlorfenapyr, fluxametamide, permethrin, and cyantraniliprole were found to be highly toxic.

Among these, fenitrothion, acetamiprid, and pyrifluquinazone also showed high mortality for larvae.

In this study, a population of rice stink bugs Niphe elongata (Dallas), inhabiting the leaves of dwarf lilyturf Ophiopogon japonicus (Thunb.) Ker Gawl was investigated. Bug trapping frequency by light traps and swooping in paddy fields was recorded using light traps and paddy fields located near the dwarf lilyturf plant. The possibility of efficiently forecasting bug outbreaks was explored using this investigation. The number of rice stink bugs captured by light traps and outbreaks in paddy fields increased after a decrease in the bug population on dwarf lilyturf. These results highlight the importance of regular monitoring of N. elongata populations on dwarf lilyturfs for forecasting rice stink bug outbreaks in paddy fields.

To identify the host plants of Pochazia shantungensis (Chou & Lu, 1977), this study investigated plant species showing egg-laying scars of P. shantungensis in fruit orchards, public parks, home gardens, and streets in northern Wakayama Prefecture. A total of 85 plant species belonging to 41 families, including fruit, ornamental and street trees, were found to be oviposited on by this species. Among fruit trees, the number of egg-laying scars was relatively high on Japanese apricot, peach, plum, citrus species, sansho, persimmon, blueberry, and pawpaw.

The Ministry of Agriculture, Forestry and Fisheries requires pesticide users to wear protective equipment to ensure their safety. For future guidance, the durability of impermeable gloves was examined. Three types of impermeable gloves were used, and nine types of emulsifiable concentrates were added to them to investigate the damage and changes that occurred. Emulsions with higher organic solvent content caused shrinkage and discoloration of the impermeable glove material, but no damage or penetration was observed. It was assumed that the impermeable gloves tested were sufficient to ensure safety.