Common Fungicides Research Articles

Fungicide Sensitivity in Strawberry Powdery Mildew Caused by Podosphaera aphanis in California.

Field observations suggest that reduced fungicide sensitivity exists in field populations of Podosphaera aphanis, the causal agent of strawberry powdery mildew (SPM). SPM is one of the most common diseases in strawberry production and is controlled with foliar fungicide applications. This study characterizes the sensitivity of 19 P. aphanis isolates to the most common fungicides used against SPM in California. Isolates were collected from commercial fruit production fields in Oxnard, Ventura, Santa Maria, Salinas, and Watsonville and from a plant nursery in Balico, California. Healthy, unfurled strawberry leaves (cultivar Monterey) free of visual disease symptoms were removed from actively growing plants and treated with one of six commercially formulated fungicides at the minimum labeled rate and inoculated with conidia of P. aphanis. Inoculated leaves were incubated at 20°C under 16/8 h of day/night lighting and assessed for disease incidence after 14 days. Pathogen growth on the treated leaflets constituted a measure of insensitivity to the fungicide. The six fungicide treatments and their average disease incidence on treated leaves for the 19 isolates are penthiopyrad (51.4%), quinoxyfen (41.5%), myclobutanil (39.8%), trifloxystrobin (19.8%), cyflufenamid (19.3%), and fluopyram + trifloxystrobin (3.5%). The average disease incidence for the trifloxystrobin treatment was raised significantly by two isolates considered to be resistant to the product (disease incidence >66.6%). Two isolates collected from organic production systems were sensitive to all fungicides. We document compromised fungicide efficacy due to resistance to most of the fungicides currently used for control of SPM in California. This is the first report of resistance in P. aphanis to any fungicide in California and the first report of resistance in P. aphanis to penthiopyrad and quinoxyfen worldwide.

Prevalence and in vitro antifungal susceptibility of commensal yeasts in the external ear canal of cats

BackgroundLifestyle factors such as hair length, the frequency of ear cleaning and bathing, age, cat rearing, and sex may contribute to opportunistic yeast infections in the external ear canal of cats. This study aimed to determine the prevalence of commensal yeast organisms in cats’ external ear canals, evaluate their predisposing lifestyle factors, and test the susceptibility of Malassezia pachydermatis to antifungal agents.ResultsA total of 53 cats (33 male and 20 female) seronegative for feline leukemia virus and feline immunodeficiency virus were enrolled in this study. Their mean age (± standard deviation) was 6.04 (± 3.49) years. Fungal cultures and polymerase chain reaction tests were performed to identify the yeast species derived from the external ear canal. The association between lifestyle factors and the presence of M. pachydermatis was evaluated using Fisher’s exact test. The susceptibility of M. pachydermatis to antifungal agents was also analyzed. M. pachydermatis was the most frequently recovered yeast species, with a prevalence of 50.94 % (95 % confidence interval [CI]: 36.84–64.94 %). There was an association between hair length and a positive culture for M. pachydermatis (p = 0.0001). The odds of a negative culture for M. pachydermatis among short-haired cats was 11.67 (95 % CI, 3.22–42.24) times higher than that among long-haired cats (p = 0.0002). There was also an association between the frequency of ear cleaning and the presence of M. pachydermatis (p = 0.007). The odds of a negative culture for M. pachydermatis in cats that were receiving ear cleaning at intervals of ≤ 2 weeks was 5.78 (95 % CI, 1.67–19.94) times greater than that of cats receiving ear cleaning at intervals greater than 2 weeks or never (p = 0.0055). Ranges of minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations for itraconazole, ketoconazole, miconazole, and terbinafine against M. pachydermatis were ≤ 0.063–4 and ≤ 0.063–≥32, ≤ 0.063–8 and 0.125–≥32, ≤ 0.063–≥32 and 0.5–≥32, and ≤ 0.016–1 and 0.125–8 µg/ml, respectively.ConclusionsM. pachydermatis was the most commonly identified yeast organism in the external ear canal of healthy cats. Hair length and the frequency of ear cleaning played a role in the colonization of M. pachydermatis. The M. pachydermatis isolates had various MIC levels for common fungicides.

Effect of Oxygen and Nitrogen Sparging during Grape Fermentation on Volatile Sulphur Compounds

Elemental sulphur is a common fungicide applied in vineyards before harvest, and has been found toincrease the production of desirable polyfunctional mercaptans, but also H2S and unwanted reductivesulphur aroma compounds. This paper investigates the effectiveness of oxygen and nitrogen sparging,applied during fermentation, on the removal of volatile sulphur compounds in Sauvignon blanc wines.Increasing the amount of elemental sulphur added to grapes after pressing, from nil to 10 to 100 mg/L,led to an increase in the formation of 3-mercaptohexanol (3MH), of 3-mercaptohexyl acetate (3MHA) forthe 10 mg/L additions only, and of some unwanted reductive compounds. Few changes were observed inthe concentrations of aroma compounds when the juices were sparged with nitrogen during fermentation.Additions of oxygen during fermentation led to some decrease in the concentration of polyfunctionalmercaptans for the 10 mg/L sulphur additions, but did not significantly remove reductive aroma compounds.Few differences were observed in the concentration of wine phenolics or of further wine aroma familieswith any of the treatments.

A common fungicide, Pristine®, impairs olfactory associative learning performance in honey bees (Apis mellifera)

Although fungicides were previously considered to be safe for important agricultural pollinators such as honey bees, recent evidence has shown that they can cause a number of behavioral and physiological sublethal effects. Here, we focus on the fungicide Pristine® (active ingredients: 25.2% boscalid, 12.8% pyraclostrobin), which is sprayed during the blooming period on a variety of crops and is known to affect honey bee mitochondria at field-relevant levels. To date, no study has tested the effects of a field-relevant concentration of a fungicide on associative learning ability in honey bees. We tested whether chronic, colony-level exposure at field-relevant and higher concentrations of Pristine® impairs performance on the proboscis extension reflex (PER) paradigm, an associative learning task. Learning performance was reduced at higher field-relevant concentrations of Pristine®. The reductions in learning performance could not be explained by effects on hunger or motivation, as sucrose responsiveness was not affected by Pristine® exposure. To determine whether Pristine®‘s negative effects on learning performance were mediated at a specific life stage, we conducted a cross-fostering experiment that exposed bees to the fungicide either only as larvae, only as adults, or during both stages. We found that exposure across the entire life was necessary to significantly reduce learning performance, although non-significant reductions occurred when bees were exposed during just one stage. Our study provides strong evidence that Pristine® has significant sublethal effects on learning performance. As associative learning is a necessary ability for foraging, our results raise concerns that Pristine® could impair foraging abilities and substantially weaken colony health.

Minimizing Lentil Harvest Loss through Improved Agronomic Practices in Sustainable Agro-Systems

Lentils are one of the most common legume crops used to diversify the cereal-oilseed cropping system in semi-arid environments. Lentils are a major source of protein and fiber for human consumption worldwide. However, the morphological characteristics of lentil plants—such as a short stem and low pod positioning—and complicated combine harvesting methods often result in yield loss. This also increases the susceptibility of a lentil crop to disease and render it less competitive against weeds. As a result, producers have resorted to using pesticides in order to mitigate the effects of weeds and disease. As a consequence, there have been undesirable negative environmental impacts on sustainable agroecosystems. Although land rolling, stubble management, and pesticide usage are common agronomic practices used to increase lentil yield and mitigate the issues associated with its morphology, their comprehensive effects on lentil growth and harvest loss are still not fully understood. In this study, we examined the impact of stubble management, the timing of land rolling, and the application of common fungicides and herbicides on lentil growth and yield. We found that stubble management and the timing of rolling modified lentil morphological structures, and thus impacted lentil yield and seed loss. These results were influenced by environmental factors, such as precipitation during the growing season. Although the results did not show significant interaction between fungicide application and lentil growth and yield, herbicide applications, stubble management, and the timing of rolling, along with common pesticide application strategies tested in our study, showed effects that were dependent on environmental conditions. Based on our results, we concluded that stubble management and the timing of rolling, combined with pesticide applications, can affect lentil seed loss and yield by modifying plant morphology. This was largely influenced by environmental conditions such as precipitation.

Development of a novel soy-wax containing emulsion with enhanced antifungal properties for the postharvest treatment of fresh citrus fruit

A novel single pendent hydroxy functionalized soy-wax was synthesized via hydroboration-oxidation of high oleic soybean oil (HBO-HOSO). Low apparent viscosity emulsions containing such wax was formulated as an alternative to the high-cost carnauba wax (CAR) and resin-based emulsions used in citrus fruit coatings, mainly to impart sheen and prevent moisture loss. The effect of additional CAR on properties of HBO-HOSO emulsions was analyzed, and the performance of the optimal formulation for citrus coating was evaluated. Addition of CAR to HBO-HOSO led to an increase in apparent viscosity, although reduced the particle size of the emulsion. An emulsion containing 20% HBO-HOSO of total solid content resulted in a low apparent viscosity and small particle size, comparable to commercial emulsions made from CAR (O-Wax and ORO), oxidized polyethylene (LS-Wax) and shellac resin (STAR). Adherence of coatings made with HBO-HOSO to the fruit surface was not significantly different compared to commercial benchmarks. The HBO-HOSO-containing emulsion provided similar gloss and resulted in reduced moisture loss (6.0%) compared to the commercial products (7.0–14.6%). HBO-HOSO-containing emulsions also did not affect the release of imazalil, a common fungicide applied on citrus fruits, and simultaneously more effectively inhibited the growth of Aspergillus niger (ATCC 16888).

Management of insect pests and diseases of jackfruit (Artocarpus heterophyllus l.) in agroforestry system: a review

The main aim of this review is to document the insect pests and diseases of jackfruit (Artocarpus heterophyllus L.) and their management in Bangladesh compared to other jackfruit growing countries. This article was based on mostly literature review. A. heterophyllus being the national fruit of Bangladesh, is widely consumed by most of the rural people. All parts of the fruit and tree are used as human food, animal feed and wood source for furniture. Jackfruit contains anti-bacterial, anti-diabetic, anti-oxidant, anti-inflammatory and anti-helminthic properties. The fruit is rich in carbohydrates, minerals, carboxylic acids, dietary fiber, vitamins and minerals. The seed is rich in manganese, magnesium, potassium, calcium iron and lectins and thus meets up nutritional requirements for the rural people. Despite the importance, a number of insect pests and diseases attack jackfruit plant and fruit. Shoot and fruit borer (Diaphania caesalis Walker) and trunk borer (Batocera rufomaculata De Geer) have been reported as major insect pests, while stem and fruit rot (Rhizopus artocarpi), bacterial dieback, pink disease (Pelliculana salmonicolor), leafspot (Phomopsis artocarpina), fruit bronzing (Pantoea stewartia Smith) and Gummosis (Phomopsis artocarpi) have been reported as major diseases. The pruning and training are an effective management technique for the insect pests and diseases. This technique provides well ventilation and reduces relative humidity at tree canopy level. Bordeaux paste is a common fungicide for the management of jackfruit borer pest and rhizopus rot, leaf spot, dieback and gummosis diseases. This paper has heighted the multifarious benefits of jackfruit plant and described the problems and solutions of jackfruit cultivation in agroforestry system of Bangladesh.

Flowering Resources Modulate the Sensitivity of Bumblebees to a Common Fungicide

Flowering Resources Modulate the Sensitivity of Bumblebees to a Common Fungicide

An environmentally safe formulation with enhanced solubility and fungicidal activity: Self-assembly and characterization of Difenoconazole-β-CD inclusion complex

Since pesticides have the disadvantages of low utilization rate and pollution to the surrounding environment, it is necessary to consider the development of new pesticide formulations. Difenoconazole (DZ), a common fungicide with poor water solubility, needs to be mixed with a large number of additives during use, which results in excessive use of organic solvents and pesticide residues. In this study, inclusion complex of beta-cyclodextrin (β-CD) and DZ was synthesized by ultrasonic method and was then aim to enhance the water solubility and its antifungal activity against Gibberella sp. of DZ. X-ray diffraction (XRD), nuclear magnetic resonance (1H NMR) analysis and molecular modeling techniques were applied to characterized the formation of DZ/β-CD inclusion complex, the DZ:β-CD stoichiometric ratio of the prepared inclusion complex was calculated in accordance with the result of 1H NMR. Increased water solubility of inclusion complex was illustrated by phase solubility studies. The inclusion complex showed a more significant fungicidal effect against Gibberella sp. than original DZ in the fungicidal effect assay. The inclusion complexation of β-CD on DZ was a new pesticide formulation and provided new development ideas for the application of DZ in agriculture.

In vitro effect of some commercial fungicides on mycelial growth of Fusarium species causing maize ear rot disease in China

Fusarium ear rot is an important disease of maize and requires several fungicide treatments to achieve satisfactory control in China. The extensive use of common fungicides to control this disease has caused fungicides resistance of pathogens. In this study, we tested the effect of different commercial fungicides on mycelial growth of Fusarium graminearum and Fusarium oxysporum isolates collected from different fields in the Jilin Province of China in 2014. The effect of concentration on mycelial growth varied significantly (p < 0.05) between tested commercial fungicides. Our results showed that among the 10 tested commercial fungicides, prochloraz and polyoxin-D highly reduced the mycelial growth of Fusarium graminearum by 3.4 cm and 4.1 cm, respectively as compared to other fungicides at a concentration of 0.1 mg/L. Moreover, a 0.1 mg/L concentration of polyoxin-D, tebuconazole, fosetyl-Al, fludioxonil, azoxystrobin, and carbendazim were also highly effective to decrease the mycelial growth of Fusarium oxysporum with 3.1 cm, 3.1 cm, 3.4 cm, 3.8 cm, and 4.4 cm as compared to other fungicides at the same concentration. These results will provide useful information to select suitable fungicides for management and control of maize ear rot disease caused by Fusarium graminearum and Fusarium oxysporum and further increase our understanding of the effects of different fungicides concentrations on Fusarium graminearum and Fusarium oxysporum.

Efficacy and Baseline Sensitivity of Succinate-Dehydrogenase-Inhibitor Fungicides for Management of Colletotrichum Crown Rot of Strawberry.

The current management of Colletotrichum crown rot (CCR) of strawberry, caused by Colletotrichum gloeosporioides sensu lato, relies on the use of a few fungicide classes, particularly QoI fungicides. Since resistance to QoI fungicides has recently been detected, alternative fungicide groups are needed to control this disease. Our objective was to evaluate the efficacy of succinate-dehydrogenase-inhibitor (SDHI) fungicides in managing CCR. Five SDHI fungicides, fluopyram, isofetamid, penthiopyrad, fluxapyroxad, and benzovindiflupyr, were applied 2 days before or 1 day after inoculation of cultivar Strawberry Festival. SDHI treatments were compared with the most common fungicides used for CCR management, i.e., thiophanate-methyl, pyraclostrobin, and captan. Benzovindiflupyr applied 1 day after inoculation was effective in reducing plant mortality and disease development. The baseline sensitivity of C. gloeosporioides isolates was determined in vitro using a spiral gradient dilution assay. The EC50 for benzovindiflupyr and penthiopyrad varied from 0.08 to 1.11 and 0.45 to 3.17 µg/ml, respectively, whereas the other SDHI fungicides did not inhibit fungal growth. If registered, benzovindiflupyr could serve as an alternative to manage CCR in Florida.

Monitoring and analysis of rice pathogen Ustilaginoidea virens isolates with resistance to sterol demethylation inhibitors in China

Rice false smut (RFS), caused by Ustilaginoidea virens (Cooke) Takah, is an important fungal disease of rice. In China, sterol demethylation inhibitors (DMIs) are common fungicides used to control RFS. In a previous study, we detected two propiconazole-resistant U. virens isolates in 2015 in Huai’an city, Jiangsu Province, China. In the current study, we detected six propiconazole-resistant isolates out of 180 U. virens isolates collected from rice fields in Jiangsu Province in 2017, and found they were from three different places (Xuzhou, Huai’an and Jintan). All these six propiconazole-resistant isolates were cross-resistant to three other sterol demethylation inhibitor (DMI) fungicides, i.e. difenoconazole, tebuconazole, and epoxiconazole. Among them, two isolates (2017–61 and 2017–170) had high fitness. Through sequencing and RT-qPCR analysis, we found that the expression levels of CYP51 and its encoded protein were significantly increased in the propiconazole-resistant isolates with a “CC” insertion mutation upstream of the CYP51 coding region compared to the propiconazole-sensitive isolates. In addition, propiconazole stimulated CYP51 expression in all isolates. Propiconazole also stimulated the accumulation of CYP51 protein in propiconazole-sensitive isolates and propiconazole-resistant isolates without mutation, but not in propiconazole-resistant isolates with the “CC” mutation. According to JASPAR database analysis, the predicated functional binding sites for propiconazole-resistant isolates with a “CC” insertion mutation and propiconazole-sensitive isolates were different. Given the high fitness of the propiconazole-resistant isolates, the development of resistance to DMIs in U. virens should be monitored. Furthermore, we speculated that the over-expression of CYP51 may contribute to DMI resistance in U. virens with the “CC” insertion mutation.

Thiabendazole vs difenoconazole in chemical control of seed-borne toxigenic fungi affecting wheat quality

Two common fungicides: Vial TrasT (60 g/l tebuconazole and 80 g/l thiabendazole) and Oplot (90 g/l difenoconazole and 45 g/l tebuconazole) were tested for effectiveness against seed-borne toxigenic fungi Fusarium spp. and Alternaria spp. using naturally infected wheat (Triricum aestivum L., cultivar Novosibirskaya-14) seeds collected from the field located near Krasnoyarsk, Russia. Treatment with Oplot statistically significantly reduced Fusarium infection by 10 percentage points (from 31.4% to 21.4%) and statistically significantly reduced Alternaria infection by 25.8 percentage points (from 42.9% to 17.1%). Treatment with Vial TrasT demonstrated no statistically significant effect in reducing infection both for Fusarium and Alternaria. The results demonstrates that populations of Fusarium spp. and Alternaria spp. in Middle Siberia have developed resistance to tebuconazole and thiabendazole, but not to difenoconazole.

Evaluation of boscalid toxicity on Daphnia magna by using antioxidant enzyme activities, the expression of genes related to antioxidant and detoxification systems, and life-history parameters

Boscalid is a succinate dehydrogenase inhibitor fungicide commonly used to control a range of plant pathogens. Although it is one of the most common fungicides in the aquatic environment, the potential adverse effects of boscalid on freshwater invertebrates still remain unclear. This study aimed to evaluate the toxicity of boscalid on Daphnia magna (D. magna) and provide new information to assess the eco-toxicity of the boscalid on aquatic invertebrates. The effects of boscalid on malondialdehyde (MDA) level, activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and the mRNA level of genes associated with antioxidant system (sod, cat, and gst) and detoxification (cytochrome P450 4 (cyp4) and nuclear respiratory factor 1 (nrf1)) were determined after 48 h treatment. The effect of boscalid on reproduction and development of D. magna was evaluated by a 21-d-chronic toxicity test. Boscalid dose-dependently altered activities of SOD, CAT, and GST and led to lipid peroxidation during acute exposure in D. magna. Exposure to 5 and 10 mg/L boscalid also significantly decreased gene expression of sod, gst, cyp4 and nrf1 but increased cat gene expression. Furthermore, chronic toxicity results showed that exposure to boscalid decreased molting frequency, number of neonates per Daphnia, and the number of broods per female as compared to the control groups. The above results indicated that boscalid had significant negative impacts on D. magna, and information present here helps to evaluate the eco-toxicity caused by boscalid on aquatic invertebrates.

Interactive effects of the neonicotinoid Thiacloprid and two common fungicides on foraging performance and reproductive success of the solitary bee Osmia bicornis under field conditions

Interactive effects of the neonicotinoid Thiacloprid and two common fungicides on foraging performance and reproductive success of the solitary bee Osmia bicornis under field conditions

Foliar Fungicides Reduce Short Term Non‐Target Soil Microbial Activity and Community Structure

Pesticides are essential in modern agricultural practices and are used frequently for the protection of crops. Fungicides are a group of pesticides that inhibit the establishment of fungal pathogens. Our systematic knowledge of the different affects fungicides have on non‐target organisms, unfortunately, is inadequate. It is difficult to determine the range of organisms affected by fungicides because of the variability and sensitivity of both eukaryotes and prokaryotes. A laboratory study was initiated to assess non‐target effects of fungicides on soil microbes. This study examined the effect of the common fungicides Tilt and Trivapro at different concentrations and incubation periods for their non‐target effects on soil microbial communities and selected activities. Three rates, 0X, 1X (0.0058 μL/cm2) and 2X (0.0116 μL/cm2) of each fungicide were applied to 100 g of Bastrop soil, common to the Blackland Prairie of Central Texas. Significantly lower CO2 was respired from amended soils compared to the control. Additionally, nitrate mineralization concentration decreased over the 30‐day trial period compared to the control. Low carbon mineralization and nitrogen mineralization rates are both attributed to a decrease in soil microbial activity. Plate counts indicate fungi (PDA) and bacteria (TSA) showed variability at two sampling dates indicating that treatment effects could not be determined solely on population counts. Our results suggest these fungicides at 1X and 2X rates have significant effects on non‐target organismal activity and community structure. Future studies will examine field applications and reassess results.Support or Funding InformationUSDA Agricultural Research Service CRIS #3098‐13610‐008‐00D

A common fungicide impairs stream ecosystem functioning through effects on aquatic hyphomycetes and detritivorous caddisflies

Fungicides can reach streams through runoff or adhered to leaf litter, and have the potential to adversely affect processes such as litter decomposition and associated communities. This study investigated the effects of chlorothalonil, a widely used fungicide, on litter decomposition, detritivorous invertebrates (larvae of the insect Sericostoma pyrenaicum) and aquatic hyphomycetes (AHs), using stream microcosms. We considered the single and combined effects of two exposure modes: waterborne fungicide (at two concentrations: 0.125 μg L−1 and 1.25 μg L−1) and litter previously sprayed with the fungicide (i.e., pre-treated litter, using the application dose concentration of 1250 μg L−1). We also assessed whether fungicide effects on invertebrates, AHs and decomposition varied among litter types (i.e., different plant species), and whether plant diversity mitigated any of those effects. Invertebrate survival and AH sporulation rate and taxon richness were strongly reduced by most combinations of fungicide exposure modes; however, invertebrates were not affected by the low waterborne concentration, whereas AHs suffered the highest reduction at this concentration. Total decomposition was slowed down by both exposure modes, and microbial decomposition was reduced by litter pre-treatment, while the waterborne fungicide had different effects depending on plant species. In general, with the exception of microbial decomposition, responses varied little among litter types. Moreover, and contrary to our expectation, plant diversity did not modulate the fungicide effects. Our results highlight the severity of fungicide inputs to streams through effects on invertebrate and microbial communities and ecosystem functioning, even in streams with well-preserved, diverse riparian vegetation.

Response of St. Augustinegrass cultivars to pinoxaden alone and in combination with select fungicides

AbstractPinoxaden is a herbicide inhibiting acetyl coenzyme A carboxylase recently introduced for use in turfgrass. Currently, pinoxaden is labeled for use in all bermudagrass [Cynodon dactylon (L.) Pers.] and zoysiagrass (Zoysia spp.) turfgrass areas except putting greens. However, pinoxaden is only labeled for use in St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] sod production because of injury concerns. Tank mixtures of two or more herbicides can reduce injury to turfgrass species. Injury reduction can also occur when fungicides are tank‐mixed with herbicides. Research was conducted between 2018 and 2019 to determine the effect that pinoxaden alone and tank mixtures of pinoxaden with one of two common fungicides, chlorothalonil and propiconazole, would have on four different cultivars of St. Augustinegrass: ‘Classic’, ‘Floratam’, ‘Palmetto’, and ‘Raleigh’. At the conclusion of the study, we determined that there is differential susceptibility to pinoxaden between cultivars of St. Augustinegrass and that both chlorothalonil and propiconazole have a safening effect on pinoxaden applications to St Augustinegrass, regardless of cultivar. The cultivars Classic and Raleigh were more susceptible to pinoxaden than Floratam and Palmetto. All four cultivars were less susceptible to pinoxaden when chlorothalonil and propiconazole were applied in combination with pinoxaden. These results suggest that pinoxaden can be applied in a tank mixture with either chlorothalonil or propiconazole to reduce pinoxaden injury to St. Augustinegrass. However, the effect that these tank mixtures may have on weed control is currently unknown.

Evaluating the Sensitivities and Efficacies of Fungicides with Different Modes of Action Against Phomopsis asparagi.

Asparagus stem blight caused by Phomopsis asparagi is a major hindrance to asparagus production worldwide. Currently, fungicides are used to manage the disease in commercial production, but resistance to common fungicides has emerged in the wild population. In the present study, 132 isolates of P. asparagi collected from different provinces in China were tested for sensitivities to pyraclostrobin, tebuconazole, and fluazinam. We also determined the efficacies of six fungicides against P. asparagi. The frequency distributions of EC50 values of the isolates tested were unimodal, but the curves for pyraclostrobin and tebuconazole had long right-hand tails. The mean EC50 values for pyraclostrobin, tebuconazole, and fluazinam were 0.0426 ± 0.0029, 0.6041 ± 0.0416, and 0.0314 ± 0.0013 μg/ml, respectively. In addition, the EC50 values for pyraclostrobin were very similar with or without salicylhydroxamic acid (SHAM), 20 μg/ml, indicating that SHAM is not needed to determine the sensitivity of P. asparagi to pyraclostrobin when using the mycelial growth inhibition assay. In greenhouse assays, Merivon (42.4% fluxapyroxad plus pyraclostrobin SC), Frown-cide (500 g/liter fluazinam SC), Cabrio (250 g/liter pyraclostrobin EC), and Nativo (75% trifloxystrobin plus tebuconazole WG) showed excellent preventive efficacy against P. asparagi. And these fungicides were more effective before inoculation than when they were applied after inoculation (P < 0.05). Therefore, these fungicides should be applied prior to infection to control stem blight. In field trials, Frown-cide, Merivon, Nativo, and Cabrio also performed good control effects, ranging from 75.2 to 86.0% in 2017 and 75.4 to 87.1% in 2018. We demonstrated that Frown-cide, Merivon, Nativo, and Cabrio had considerable potential to manage asparagus stem blight. In addition, rotations of these fungicides are essential for precluding or delaying the development of resistance and for controlling the disease.

Acute thiamethoxam toxicity in honeybees is not enhanced by common fungicide and herbicide and lacks stress-induced changes in mRNA splicing

Securing food supply for a growing population is a major challenge and heavily relies on the use of agrochemicals to maximize crop yield. It is increasingly recognized, that some neonicotinoid insecticides have a negative impact on non-target organisms, including important pollinators such as the European honeybee Apis mellifera. Toxicity of neonicotinoids may be enhanced through simultaneous exposure with additional pesticides, which could help explain, in part, the global decline of honeybee colonies. Here we examined whether exposure effects of the neonicotinoid thiamethoxam on bee viability are enhanced by the commonly used fungicide carbendazim and the herbicide glyphosate. We also analysed alternative splicing changes upon pesticide exposure in the honeybee. In particular, we examined transcripts of three genes: (i) the stress sensor gene X box binding protein-1 (Xbp1), (ii) the Down Syndrome Cell Adhesion Molecule (Dscam) gene and iii) the embryonic lethal/abnormal visual system (elav) gene, which are important for neuronal function. Our results showed that acute thiamethoxam exposure is not enhanced by carbendazim, nor glyphosate. Toxicity of the compounds did not trigger stress-induced, alternative splicing in the analysed mRNAs, thereby leaving dormant a cellular response pathway to these man-made environmental perturbations.