Resistance of<i>Venturia inaequalis</i>to bitertanol and other demethylation-inhibiting fungicides

Hildebrand, P.D.; Lockhart, C. L.; Newbery, R. J.; Ross, R. G.

doi:10.1080/07060668809501704

Cited by 61 publications

(37 citation statements)

References 15 publications

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“…The short time required to build up significant resistance levels may be due to the fact that DMI fungicides have been used in this area since 1985. In contrast to our findings, it took 7 years of fungicide application to induce resistance in a Canadian orchard (13). This clearly indicates that the equation presented here cannot be applied to other fruit-growing regions.…”

Section: Discussioncontrasting

confidence: 55%

“…While no resistance was detected in an American orchard after 12 years of extensive DMI application (30), complete control failure occurred in a Canadian orchard with a comparable number of DMI treatments (13,16). This contradiction may be due to differences in infection pressure (16).…”

Section: Introductionmentioning

confidence: 99%

“…Since DMI fungicides represent single-site inhibitors interfering with C-14 demethylation of 24-methylendihydrolanosterol in ergosterol biosynthesis (6,18), a high risk of development of resistance exists (18). In fact, resistance problems have been observed in several pathogens including powdery mildews (10,11,25), Penicillium digitatum (7), Pyrenophora teres (26), Sclerotinia homoeocarpa (9), and Venturia inaequalis (13). Isolates of V. inaequalis with reduced sensitivities to several DMI fungicides have been reported to occur worldwide (4,13,23,24,31,32).…”

mentioning

confidence: 99%

“…In fact, resistance problems have been observed in several pathogens including powdery mildews (10,11,25), Penicillium digitatum (7), Pyrenophora teres (26), Sclerotinia homoeocarpa (9), and Venturia inaequalis (13). Isolates of V. inaequalis with reduced sensitivities to several DMI fungicides have been reported to occur worldwide (4,13,23,24,31,32). Resistance to DMI fungicides is under multigenic control, increasing gradually by additive action of the different resistance genes (6,15).…”

mentioning

confidence: 99%

“…Depending on the stringency of the selection pressure, sensitivity of V. inaequalis populations may, therefore, shift gradually from baseline sensitivity to a distinct level of resistance (1,8,20). The exclusive and frequent use of DMI fungicides may thus lead to complete control failure in the field (13,23).…”

mentioning

confidence: 99%

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Acquisition of Resistance to Sterol Demethylation Inhibitors by Populations of Venturia inaequalis

Kunz¹,

Deising²,

Mendgen³

1997

Phytopathology®

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Kunz, S., Deising, H., and Mendgen, K. 1997. Acquisition of resistance to sterol demethylation inhibitors by populations of Venturia inaequalis. Phytopathology 87:1272-1278.Acquisition of resistance to sterol demethylation inhibitors (DMIs) by populations of Venturia inaequalis was investigated using a microscopical method developed by C. Siebels and K. Mendgen. Microscopical analysis of conidiophore formation enabled the earlier detection of resistance and a clearer distinction between DMI-resistant and DMI-sensitive populations than other in vivo methods commonly used to analyze inhibitory effects of fungicides. In addition, because observations were made on the level of individuals, quantitative measures of the composition of conidial populations were obtained. The development of DMI sensitivity was followed over a period of 3 years in control apple orchards that had never been treated with fungicides and in orchards with DMI history. The 50% effective dose values determined by microscopical evaluation of conidiophore development for untreated populations revealed the baseline sensitivities of 0.3, 0.96, 0.09, 1.22, and 1.92 mg/liter for flusilazole, fenarimol, difenoconazole, tebuconazole, and pyrifenox, respectively. As compared with the baseline sensitivity, all populations with DMI history showed significant resistance to flusilazole. A strong nonlinear correlation (R = 0.96) was found between the resistance factors and the sum of all DMI treatments of the 3 years before taking the sample. According to this correlation, resistance can be expected in all apple orchards of the fruitgrowing area along Lake Constance, Germany, in which more than two DMI treatments per season have been applied. Due to cross-resistance, the recently introduced DMI fungicides difenoconazole, tebuconazole, and pyrifenox did not allow the control of V. inaequalis populations resistant to flusilazole.The success of modern, integrated disease control strategies strongly depends on the availability of efficient curative fungicides (2). Until 1995, sterol demethylation inhibitors (DMIs) were the only curative fungicides registered for use in apple orchards in Germany. Since DMI fungicides represent single-site inhibitors interfering with C-14 demethylation of 24-methylendihydrolanosterol in ergosterol biosynthesis (6,18), a high risk of development of resistance exists (18). In fact, resistance problems have been observed in several pathogens including powdery mildews (10,11,25), Penicillium digitatum (7), Pyrenophora teres (26), Sclerotinia homoeocarpa (9), and Venturia inaequalis (13). Isolates of V. inaequalis with reduced sensitivities to several DMI fungicides have been reported to occur worldwide (4,13,23,24,31,32). Resistance to DMI fungicides is under multigenic control, increasing gradually by additive action of the different resistance genes (6,15). Depending on the stringency of the selection pressure, sensitivity of V. inaequalis populations may, therefore, shift gradually from baseline sensitivity to a distinct le...

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Section: Discussioncontrasting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Acquisition of Resistance to Sterol Demethylation Inhibitors by Populations of Venturia inaequalis

Kunz¹,

Deising²,

Mendgen³

1997

Phytopathology®

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Reduced sensitivity to fenarimol in Japanese field strains ofVenturia nashicola

Tomita¹,

Ishii

1998

Pestic. Sci.

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Monoconidial strains of Venturia nashicola Tanaka et Yamamoto were isolated from Japanese or Chinese white pear trees which had never been treated with sterol demethylation inhibitors (DMIs) and their baseline sensitivities to fenarimol were determined by mycelial growth tests on fungicide‐amended culture media. Strains were also obtained from Japanese pear orchards, which had been intensively treated with DMIs for several years and monitored for the shifts of fenarimol sensitivity in comparison with the baseline sensitivity. Results suggested slight shifts to lower fenarimol sensitivity in strains isolated from DMI‐treated Japanese pear orchards. However, in inoculation tests on pear seedlings, fenarimol still provided adequate control of V. nashicola strains with reduced sensitivity to fenarimol in vitro, suggesting that the performance of this fungicide will still be maintained in the field. © 1998 Society of Chemical Industry

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Within‐ and between‐orchard variability in the sensitivity of Venturia inaequalis to myclobutanil, a DMI fungicide, in the UK

Gao

Berrie

Yang

et al. 2009

Pest Management Science

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Resistance ofVenturia inaequalisto bitertanol and other demethylation-inhibiting fungicides

Cited by 61 publications

References 15 publications

Acquisition of Resistance to Sterol Demethylation Inhibitors by Populations of Venturia inaequalis

Acquisition of Resistance to Sterol Demethylation Inhibitors by Populations of Venturia inaequalis

Reduced sensitivity to fenarimol in Japanese field strains ofVenturia nashicola

Within‐ and between‐orchard variability in the sensitivity of Venturia inaequalis to myclobutanil, a DMI fungicide, in the UK

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