Azoxystrobin

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James E. Adaskaveg - One of the best experts on this subject based on the ideXlab platform.

  • baseline sensitivities for new postharvest fungicides against penicillium spp on citrus and multiple resistance evaluations in p digitatum
    Plant Disease, 2008
    Co-Authors: Loukas Kanetis, H Forster, James E. Adaskaveg
    Abstract:

    ABSTRACT For the first time in over 25 years, three new fungicides (Azoxystrobin, fludioxonil, and pyrimethanil), all belonging to different chemical classes, are being registered for postharvest use against Penicillium decays of citrus fruit in the United States. Baseline sensitivities of Penicillium digitatum and P. italicum were developed using isolates collected before the commercial use of these new fungicides. In a comparison of methods, EC50 values obtained using the spiral gradient dilution method were very similar to those obtained using traditional agar dilutions of fungicides. For Azoxystrobin, the addition of salicylhydroxamic acid (SHAM) did not significantly affect EC50 values for mycelial growth of both species. In additional studies on conidial germination of P. digitatum, SHAM significantly reduced EC50 values for Azoxystrobin. For pyrimethanil, the mean EC50 value for mycelial growth obtained using a minimum growth medium for anilinopyrimidine fungicides was significantly lower but compa...

  • comparative efficacy of the new postharvest fungicides Azoxystrobin fludioxonil and pyrimethanil for managing citrus green mold
    Plant Disease, 2007
    Co-Authors: Loukas Kanetis, Helga Förster, James E. Adaskaveg
    Abstract:

    ABSTRACT Three new fungicides (i.e., Azoxystrobin, fludioxonil, and pyrimethanil) are currently being introduced for postharvest management of citrus green mold in the United States. The effectiveness of each fungicide was evaluated when applied alone (at 1,000 to 1,200 mg/liter) or in mixtures (at 500 mg/liter each component) to lemon fruit that were wound-inoculated with imazalil/thiabendazole (TBZ)-sensitive or -resistant isolates of Penicillium digitatum. In laboratory studies when aqueous fungicide solutions were applied 9 to 21 h after inoculation, pyrimethanil showed the highest level of green mold control. The efficacy of fludioxonil and Azoxystrobin was very high at the early timings, but decreased as time after inoculation increased. Differences in fungicide performance were not due to multiple fungicide resistance, but more likely due to differences in fungicide mobility in fruit tissue. Azoxystrobin-fludioxonil mixtures were significantly more effective when compared to single-fungicide treatm...

  • comparative efficacy of the new postharvest fungicides Azoxystrobin fludioxonil and pyrimethanil for managing citrus green mold
    Plant Disease, 2007
    Co-Authors: Loukas Kanetis, Helga Förster, James E. Adaskaveg
    Abstract:

    Three new fungicides (i.e., Azoxystrobin, fludioxonil, and pyrimethanil) are currently being introduced for postharvest management of citrus green mold in the United States. The effectiveness of each fungicide was evaluated when applied alone (at 1,000 to 1,200 mg/liter) or in mixtures (at 500 mg/liter each component) to lemon fruit that were wound-inoculated with imazalil/thiabendazole (TBZ)-sensitive or -resistant isolates of Penicillium digitatum. In laboratory studies when aqueous fungicide solutions were applied 9 to 21 h after inoculation, pyrimethanil showed the highest level of green mold control. The efficacy of fludioxonil and Azoxystrobin was very high at the early timings, but decreased as time after inoculation increased. Differences in fungicide performance were not due to multiple fungicide resistance, but more likely due to differences in fungicide mobility in fruit tissue. Azoxystrobin-fludioxonil mixtures were significantly more effective when compared to single-fungicide treatments. Mixtures of imazalil with pyrimethanil were the most effective in controlling decay. The efficacy of all fungicides was significantly lower when mixed into a packing fruit coating as compared to aqueous or storage fruit coating applications. In laboratory and packingline studies, the lowest incidence of green mold decay was obtained when Azoxystrobin-fludioxonil and imazalil-pyrimethanil were applied as aqueous solutions that were followed by a fruit coating. Among the new fungicides, Azoxystrobin and fludioxonil applied in water or storage fruit coating, respectively, provided the best anti-sporulation activity. Storage fruit coating improved the activity of both fungicides. Pyrimethanil was the least effective fungicide in suppressing sporulation of the pathogen on decaying fruit. Overall, among the mixtures, Azoxystrobin-fludioxonil and TBZ-fludioxonil had high anti-sporulation activity in aqueous and storage fruit coating applications. New integrated management programs should be based on monitoring of fungicide sensitivities in pathogen populations, rotating mixtures of products with different modes of action, and using appropriate fungicide application strategies.

Loukas Kanetis - One of the best experts on this subject based on the ideXlab platform.

  • baseline sensitivities for new postharvest fungicides against penicillium spp on citrus and multiple resistance evaluations in p digitatum
    Plant Disease, 2008
    Co-Authors: Loukas Kanetis, H Forster, James E. Adaskaveg
    Abstract:

    ABSTRACT For the first time in over 25 years, three new fungicides (Azoxystrobin, fludioxonil, and pyrimethanil), all belonging to different chemical classes, are being registered for postharvest use against Penicillium decays of citrus fruit in the United States. Baseline sensitivities of Penicillium digitatum and P. italicum were developed using isolates collected before the commercial use of these new fungicides. In a comparison of methods, EC50 values obtained using the spiral gradient dilution method were very similar to those obtained using traditional agar dilutions of fungicides. For Azoxystrobin, the addition of salicylhydroxamic acid (SHAM) did not significantly affect EC50 values for mycelial growth of both species. In additional studies on conidial germination of P. digitatum, SHAM significantly reduced EC50 values for Azoxystrobin. For pyrimethanil, the mean EC50 value for mycelial growth obtained using a minimum growth medium for anilinopyrimidine fungicides was significantly lower but compa...

  • comparative efficacy of the new postharvest fungicides Azoxystrobin fludioxonil and pyrimethanil for managing citrus green mold
    Plant Disease, 2007
    Co-Authors: Loukas Kanetis, Helga Förster, James E. Adaskaveg
    Abstract:

    ABSTRACT Three new fungicides (i.e., Azoxystrobin, fludioxonil, and pyrimethanil) are currently being introduced for postharvest management of citrus green mold in the United States. The effectiveness of each fungicide was evaluated when applied alone (at 1,000 to 1,200 mg/liter) or in mixtures (at 500 mg/liter each component) to lemon fruit that were wound-inoculated with imazalil/thiabendazole (TBZ)-sensitive or -resistant isolates of Penicillium digitatum. In laboratory studies when aqueous fungicide solutions were applied 9 to 21 h after inoculation, pyrimethanil showed the highest level of green mold control. The efficacy of fludioxonil and Azoxystrobin was very high at the early timings, but decreased as time after inoculation increased. Differences in fungicide performance were not due to multiple fungicide resistance, but more likely due to differences in fungicide mobility in fruit tissue. Azoxystrobin-fludioxonil mixtures were significantly more effective when compared to single-fungicide treatm...

  • comparative efficacy of the new postharvest fungicides Azoxystrobin fludioxonil and pyrimethanil for managing citrus green mold
    Plant Disease, 2007
    Co-Authors: Loukas Kanetis, Helga Förster, James E. Adaskaveg
    Abstract:

    Three new fungicides (i.e., Azoxystrobin, fludioxonil, and pyrimethanil) are currently being introduced for postharvest management of citrus green mold in the United States. The effectiveness of each fungicide was evaluated when applied alone (at 1,000 to 1,200 mg/liter) or in mixtures (at 500 mg/liter each component) to lemon fruit that were wound-inoculated with imazalil/thiabendazole (TBZ)-sensitive or -resistant isolates of Penicillium digitatum. In laboratory studies when aqueous fungicide solutions were applied 9 to 21 h after inoculation, pyrimethanil showed the highest level of green mold control. The efficacy of fludioxonil and Azoxystrobin was very high at the early timings, but decreased as time after inoculation increased. Differences in fungicide performance were not due to multiple fungicide resistance, but more likely due to differences in fungicide mobility in fruit tissue. Azoxystrobin-fludioxonil mixtures were significantly more effective when compared to single-fungicide treatments. Mixtures of imazalil with pyrimethanil were the most effective in controlling decay. The efficacy of all fungicides was significantly lower when mixed into a packing fruit coating as compared to aqueous or storage fruit coating applications. In laboratory and packingline studies, the lowest incidence of green mold decay was obtained when Azoxystrobin-fludioxonil and imazalil-pyrimethanil were applied as aqueous solutions that were followed by a fruit coating. Among the new fungicides, Azoxystrobin and fludioxonil applied in water or storage fruit coating, respectively, provided the best anti-sporulation activity. Storage fruit coating improved the activity of both fungicides. Pyrimethanil was the least effective fungicide in suppressing sporulation of the pathogen on decaying fruit. Overall, among the mixtures, Azoxystrobin-fludioxonil and TBZ-fludioxonil had high anti-sporulation activity in aqueous and storage fruit coating applications. New integrated management programs should be based on monitoring of fungicide sensitivities in pathogen populations, rotating mixtures of products with different modes of action, and using appropriate fungicide application strategies.

Lihong Qiu - One of the best experts on this subject based on the ideXlab platform.

  • parental exposure to Azoxystrobin causes developmental effects and disrupts gene expression in f1 embryonic zebrafish danio rerio
    Science of The Total Environment, 2019
    Co-Authors: Fangjie Cao, Christopher J Martyniuk, Lan Huang, Le Qian, Sen Pang, Feng Zhao, Lihong Qiu
    Abstract:

    Abstract The fungicide Azoxystrobin induces reproductive toxicity in adult zebrafish. However, data are lacking regarding the impact of Azoxystrobin in the F1 generation after parental exposure. To address this knowledge gap, parental zebrafish (F0) were exposed to 2, 20 and 200 μg/L Azoxystrobin for 21 days. Following this, fertilized F1 embryos from the exposed parents were either exposed to the same concentration as their corresponding exposed parents (F0+/F1+) or were reared in clean water (F0+/F1−) for 96 h (“+”, exposed; “−” unexposed). Likewise, F1 embryos from the non-exposed parents were either reared in clean water (F0−/F0−) as the control group or were exposed to 2, 20 and 200 μg/L Azoxystrobin (F0−/F1+) for 96 h. Mortality, deformities, hatching rate, body length, and the expression of transcripts related to the endocrine system, oxidative stress, and apoptosis were measured. Increased mortality, higher malformation rate, decreased hatching rate, and a shorter total body length, as well as up-regulated cyp19b, vtg1, vtg2, p53, casp3, and casp9 mRNA and down-regulated sod1 and sod2 mRNA were detected in F1 embryos from the F0 and F1 exposure group at 20 and 200 μg/L Azoxystrobin (F0+/F1+) when compared with the group from the F0 exposure alone (F0+/F1−). Interestingly, F1 exposure alone (F0−/F1+) did not induce mortality, developmental impairments, nor morphological deformations compared to the control group, but it did increase expression level of sod1, sod2, cat, p53, and casp9 at 200 μg/L Azoxystrobin. Taken together, these data suggest that Azoxystrobin affects survivability, development, and genes involved in the endocrine system, oxidative stress, and apoptosis in F1 embryos if their parents are initially exposed to this fungicide compared to embryos from non-exposed parents. Moreover, the effects are more severe if the offspring are continuously exposed to Azoxystrobin similar to their parents.

  • short term developmental effects and potential mechanisms of Azoxystrobin in larval and adult zebrafish danio rerio
    Aquatic Toxicology, 2018
    Co-Authors: Fangjie Cao, Lan Huang, Le Qian, Sen Pang, Lihong Qiu
    Abstract:

    Abstract Previous study indicated that Azoxystrobin had high acute toxicity to zebrafish, and larval zebrafish were more sensitive to Azoxystrobin than adult zebrafish. The objective of the present study was to investigate short-term developmental effects and potential mechanisms of Azoxystrobin in larval and adult zebrafish. After zebrafish embryos and adults were exposed to 0.01, 0.05 and 0.20 mg/L Azoxystrobin (equal to 25, 124 and 496 nM Azoxystrobin, respectively) for 8 days, the lethal effect, physiological responses, liver histology, mitochondrial ultrastructure, and expression alteration of genes related to mitochondrial respiration, oxidative stress, cell apoptosis and innate immune response were determined. The results showed that there was no significant effect on larval and adult zebrafish after exposure to 0.01 mg/L Azoxystrobin. However, increased ROS, MDA concentration and il1b in larval zebrafish, as well as increased il1b, il8 and cxcl-c1c in adult zebrafish were induced after exposure to 0.05 mg/L Azoxystrobin. Reduced mitochondrial complex III activity and ATP concentration, increased SOD activity, ROS and MDA concentration, decreased cytb, as well as increased sod1, sod2, cat, il1b, il8 and cxcl-c1c were observed both in larval and adult zebrafish after exposure to 0.20 mg/L Azoxystrobin; meanwhile, increased p53, bax, apaf1 and casp9, alteration of liver histology and mitochondrial ultrastructure in larval zebrafish, and alteration of mitochondrial ultrastructure in adult zebrafish were also induced. The results demonstrated that azoxytrobin induced short-term developmental effects on larval zebrafish and adult zebrafish, including mitochondrial dysfunction, oxidative stress, cell apoptosis and innate immune response. Statistical analysis indicated that Azoxystrobin induced more negative effects on larval zebrafish, which might be the reason for the differences of developmental toxicity between larval and adult zebrafish caused by Azoxystrobin. These results provided a new insight into potential mechanisms of Azoxystrobin in larval zebrafish and adult zebrafish.

  • reproductive toxicity of Azoxystrobin to adult zebrafish danio rerio
    Environmental Pollution, 2016
    Co-Authors: Fangjie Cao, Lizhen Zhu, Chengju Wang, Lihong Qiu
    Abstract:

    In the past few decades, extensive application of Azoxystrobin has led to great concern regarding its adverse effects on aquatic organisms. The objective of the present study was to evaluate the reproductive toxicity of Azoxystrobin to zebrafish. After adult zebrafish of both sexes were exposed to 2, 20 and 200 μg/L Azoxystrobin for 21 days, egg production, the fertilization rate, the gonadosomatic index (GSI) and hepatosomatic index (HSI), 17β-estradiol (E2), testosterone (T) and vitellogenin (Vtg) concentrations, and histological alterations in the gonads and livers were measured. Meanwhile, expression alterations of genes encoding gonadotropins and gonadotropin receptors (fshb, lhb, fshr and lhr), steroid hormone receptors (era, er2b and ar), steroidogenic enzymes (cyp11a, cyp11b, cyp17, cyp19a, cyp19b, hsd3b and hsd17b) in the hypothalamic-pituitary-gonad (HPG) axis and vitellogenin (vtg1 and vtg2) in the livers were also investigated. The results showed that reduced egg production and fertilization rates were observed at 200 μg/L Azoxystrobin. In female zebrafish, reduced E2 and Vtg concentrations, decreased GSI, increased T concentrations, and histological alterations in the ovaries and livers were observed at 200 μg/L Azoxystrobin, along with significant down-regulation of lhb, cyp19b, lhr, cyp19a, vtg1 and vtg2, and up-regulation of cyp17, hsd3b and hsd17b. In male zebrafish, increased E2 and Vtg concentrations, reduced T concentration and GSI, and histological alterations in the testes and livers were observed after exposure to 20 and 200 μg/L Azoxystrobin, along with significant up-regulations of cyp19b, cyp11a, cyp17, cyp19a, hsd3b and hsd17b, vtg1 and vtg2. Moreover, cyp11a, hsd3b, cyp19a, vtg1 and vtg2 in male zebrafish were significantly up-regulated after treatment with 2 μg/L Azoxystrobin. The results of the present study indicate that Azoxystrobin led to reproductive toxicity in zebrafish and male zebrafish were more sensitive to Azoxystrobin than female zebrafish.

Wayne F Wilcox - One of the best experts on this subject based on the ideXlab platform.

  • sensitivity to Azoxystrobin among isolates of uncinula necator baseline distribution and relationship to myclobutanil sensitivity
    Plant Disease, 2002
    Co-Authors: Francis P Wong, Wayne F Wilcox
    Abstract:

    Two hundred fifty-six single-conidial chain isolates of Uncinula necator were assayed for their sensitivity to Azoxystrobin and myclobutanil. These isolates were collected from two sites in New York in 1999: an "organic" vineyard where no synthetic fungicides have been used (baseline population) and a commercial vineyard having a history of compromised powdery mildew control with myclobutanil (demethylation inhibitor [DMI]-resistant population). Mean coefficients of variance for a leaf disk assay used to test fungicide sensitivities were 31% for Azoxystrobin and 41% for myclobutanil. Baseline ED50 values ranged from 0.0037 to 0.028 μg/ml (mean 0.0097μg/ml) for Azoxystrobin and from 0.0049 to 0.69 μg/ml (mean 0.075 μg/ml) for myclobutanil. A shift in the mean ED50 value for Azoxystrobin to 0.018 μg/ml was observed in the DMI-resistant population; with the strongest shift observed for isolates collected from vines treated exclusively with myclobutanil (0.024 μg/ml). For the 256 tested isolates, there was a moderate, but statistically significant, correlation between Azoxystrobin and myclobutanil sensitivities (R2 = 0.36, P < 0.001). Tests with three other strobilurin fungicides (kresoxim-methyl, pyraclostrobin, and trifloxystrobin) indicate clear differences in the intrinsic activity of these compounds against U. necator, and the applicability of the methods developed with Azoxystrobin for assays with pyraclostrobin and trifloxystrobin. Isolates from the high and low ends of the Azoxystrobin sensitivity distribution (15× difference in mean ED50 values) were equally controlled in planta by protectant or postinfection treatment with Azoxystrobin at 250 μg a.i./ml, but postinfection application at lower rates (2.5 and 25 μg a.i./ml) resulted in a 41 and 44% decrease, respectively, in the control of the low-sensitivity isolates versus high-sensitivity isolates. The results of this study document the baseline sensitivity distribution of U. necator to Azoxystrobin, provide evidence of partial cross-sensitivity between Azoxystrobin and myclobutanil, and illustrate the potential selection for individuals with reduced sensitivity (quantitative range) to Azoxystrobin by postinfection application and reduced rates of this fungicide.

  • comparative physical modes of action of Azoxystrobin mancozeb and metalaxyl against plasmopara viticola grapevine downy mildew
    Plant Disease, 2001
    Co-Authors: Francis P Wong, Wayne F Wilcox
    Abstract:

    ABSTRACT The physical modes of action of Azoxystrobin, mancozeb, and metalaxyl were evaluated on grapevine seedlings using Plasmopara viticola as a model pathogen. The protectant, postinfection, postsymptom, translaminar, and vapor activities of Azoxystrobin were evaluated at a rate of 250 μg/ml. Azoxystrobin provided 100% disease control when applied 1 to 5 days before inoculation. Postinfection applications of Azoxystrobin had little effect on the incidence of disease, but colony area and sporulation from the resultant lesions was reduced by 47 and 96%, respectively, relative to the check treatment when applied up to 5 days after inoculation. Postsymptom applications (6 days after inoculation) of Azoxystrobin resulted in an 85% mean reduction of resporulation from diseased tissue relative to the check when seedlings were evaluated 1 to 14 days after treatment. Translaminar activity was greatest when the upper surface of the leaf was treated 7 days before inoculation of the lower leaf surface (94% diseas...

  • comparative physical modes of action of Azoxystrobin mancozeb and metalaxyl against plasmopara viticola grapevine downy mildew
    Plant Disease, 2001
    Co-Authors: Francis P Wong, Wayne F Wilcox
    Abstract:

    The physical modes of action of Azoxystrobin, mancozeb, and metalaxyl were evaluated on grapevine seedlings using Plasmopara viticola as a model pathogen. The protectant, postinfection, postsymptom, translaminar, and vapor activities of Azoxystrobin were evaluated at a rate of 250 μg/ml. Azoxystrobin provided 100% disease control when applied 1 to 5 days before inoculation. Postinfection applications of Azoxystrobin had little effect on the incidence of disease, but colony area and sporulation from the resultant lesions was reduced by 47 and 96%, respectively, relative to the check treatment when applied up to 5 days after inoculation. Postsymptom applications (6 days after inoculation) of Azoxystrobin resulted in an 85% mean reduction of resporulation from diseased tissue relative to the check when seedlings were evaluated 1 to 14 days after treatment. Translaminar activity was greatest when the upper surface of the leaf was treated 7 days before inoculation of the lower leaf surface (94% disease control). In contrast, control was <50% when leaves were similarly inoculated 1 and 3 days after treatment. Vapor activity was not pronounced, providing maximum reductions of 5, 11, and 37%, with regard to incidence, colony area, and sporulation, relative to the check when seedlings were treated 1 to 7 days before inoculating adjacent, untreated leaves. Comparatively, mancozeb (1,790 μg/ml) provided complete control of the disease when applied 1 to 5 days before inoculation, but showed little postinfection activity in reducing disease incidence, although it exhibited moderate to high antisporulant activity when applied in postinfection and postsymptom modes (mean reductions of 38 and 89%, respectively, compared with the check treatments). Metalaxyl (260 μg/ml) also provided complete control of the disease when used in protectant mode, and also when applied 1 day after inoculation. Applications at 3 to 5 days after inoculation provided substantial reductions in disease severity and sporulation (mean reductions of 46 and 94%, respectively, compared with the check treatments), and postsymptom applications resulted in a mean 84% reduction in resporulation. Collectively, the results of this study illustrate the unique physical modes of action for Azoxystrobin in comparison to that of two traditional protectant and systemic fungicides, and provide information on how Azoxystrobin and other strobilurin fungicides with similar physical modes of action should be best used in disease management programs.

Guido Schnabel - One of the best experts on this subject based on the ideXlab platform.

  • Reduced sensitivity of Azoxystrobin and thiophanate-methyl resistance in Lasiodiplodia theobromae from papaya.
    Pesticide Biochemistry and Physiology, 2020
    Co-Authors: Fengping Chen, Susan Satie Tsuji, Moara Alexandrino Bandeira, Marcos Paz Saraiva Câmara, Sami J. Michereff, Guido Schnabel
    Abstract:

    Stem-end rot caused by Lasiodiplodia theobromae is one of the most devastating diseases of papaya in northeastern Brazil. It is most effectively controlled by applications of fungicides, including site-specific fungicides at risk for resistance development. This study investigated the molecular mechanisms of reduced sensitivity to the QoI fungicide Azoxystrobin and resistance to the MBC fungicide thiophanate-methyl in L. theobromae from Brazilian orchards. The EC50 values for Azoxystrobin in sixty-four isolates ranged from 0.36 μg/ml to 364.24 μg/ml and the frequency distribution of EC50 values formed a multimodal curve, indicating reduced sensitivity to Azoxystrobin. In detached fruit assays reduced sensitive isolates were not controlled as effectively as sensitive isolates at lowest label rate. Partial fragments were obtained from target genes β-tubulin (751 bp) and Cytb (687 bp) of isolates resistant to thiophanate-methyl and reduced sensitivity to Azoxystrobin. Sequence analysis of the β-tubulin fragment revealed a mutation corresponding to E198K in all thiophanate-methyl-resistant isolates, while reduced sensitivity to axoxystrobin was not attributable to Cytb gene alterations. The target gene-based mechanism conferring resistance to thiophanate-methyl will likely be stable even if selection pressure subsides. However, the mechanism conferring reduced sensitivity to Azoxystrobin is not based on target gene modifications and thus may not be as stable as other genotypes with mutations in Cytb gene.

  • adaptation to fungicides in monilinia fructicola isolates with different fungicide resistance phenotypes
    Phytopathology, 2008
    Co-Authors: Chaoxi Luo, Guido Schnabel
    Abstract:

    The ability to develop fungicide resistance was assessed in Monilinia fructicola isolates with different fungicide sensitivity phenotypes by adapting mycelium and conidia to increasing concentrations of selective fungicides and UV mutagenesis. Results showed that adaptation to Quinone outside inhibitor (QoI) fungicide Azoxystrobin and sterol demethylation inhibitor (DMI) fungicide propiconazole was more effective in conidial-transfer experiments compared to mycelial-transfer experiments. DMI-resistant (DMI-R) isolates adapted to significantly higher doses of Azoxystrobin in both, mycelial- and conidial-transfer experiments compared to benzimidazole-resistant (BZI-R) and sensitive (S) isolates. Adaptation to propiconazole in conidial-transfer experiments was accelerated in BZI-R isolates when a stable, nonlethal dose of 50 microg/ml thiophanate-methyl was added to the selection medium. One of two Azoxystrobin-resistant mutants from DMI-R isolates did not show any fitness penalties; the other isolate expired before further tests could be carried out. The viable mutant caused larger lesions on detached peach fruit sprayed with Azoxystrobin compared to the parental isolate. The Azoxystrobin sensitivity of the viable mutant returned to baseline levels after the mutant was transferred to unamended medium. However, Azoxystrobin resistance recovered quicker in the mutant compared to the corresponding parental isolate after renewed subculturing on medium amended with 0.2 and 1 microg/ml Azoxystrobin; only the mutant but not the parental isolate was able to adapt to 5 microg/ml Azoxystrobin. In UV mutagenesis experiments, the DMI-R isolates produced significantly more mutants compared to S isolates. All of the UV-induced mutants showed stable fungicide resistance with little fitness penalty. This study indicates the potential for QoI fungicide resistance development in M. fructicola in the absence of a mutagen and provides evidence for increased mutability and predisposition to accelerated adaptation to Azoxystrobin in M. fructicola isolates resistant to DMI fungicides.