Survey and Screening of Benomyl Resistant Strains of Cercospora beticola in Minnesota and North Dakota

J.A. Percich; M.W. Hotchkiss; L.J. Nickelson

doi:10.5274/jsbr.23.3.148

Control of Benzimidazole- and DMI-Resistant Strains of Cercospora beticola with Strobilurin Fungicides

Plant Disease ◽

10.1094/pd-90-0419 ◽

2006 ◽

Vol 90 (4) ◽

pp. 419-424 ◽

Cited By ~ 13

Author(s):

G. S. Karaoglanidis ◽

G. Bardas

Keyword(s):

Resistant Isolate ◽

Cercospora Beticola ◽

Control Efficacy ◽

Benzimidazole Fungicides ◽

High Frequencies ◽

Strobilurin Fungicides ◽

Evolution Of Resistance ◽

Dmi Fungicides ◽

Strobilurin Fungicide ◽

Resistant Strains

The control efficacy of two new strobilurin fungicides, trifloxystrobin and pyraclostrobin, against Cercospora beticola isolates resistant and sensitive to sterol demethylation-inhibiting (DMI) fungicides and benzimidazole fungicides and the effects on evolution of resistance were tested in the current study. Control efficacy of strobilurin fungicides was measured using three C. beticola isolates, one DMI-resistant (DMIR), one benzimidazole-resistant (BENR), and one of wild-type sensitivity (WCB). Both pyraclostrobin and trifloxystrobin provided satisfactory control of all the three isolates used in the study, when applied at 5 μg ml-1 and very high levels of control when applied at 10 μg ml-1. Control was independent of the isolate sensitivity to benomyl and difenoconazole. In contrast, benomyl applied at 10 μg ml-1 failed to control sufficiently the benzimidazole-resistant isolate, whereas difenoconazole applied at either 5 or 10 μg ml-1 failed to provide satisfactory control of the DMI-resistant isolate of the pathogen. The effects of strobilurin fungicide applications on the evolution of resistance to benzimidazole and DMI fungicides were tested under field conditions in a 2-year experiment (2003 to 2004). Applications of either trifloxystrobin or pyraclostrobin provided high levels of disease control during both years of the study, whereas applications of either benomyl or difenoconazole provided a moderate control efficacy. Measurements of resistance frequencies to benomyl and to difenoconazole showed that successive applications of benomyl tended to select for high frequencies of benzimidazole-resistant phenotypes, whereas successive applications of difenoconazole tended to select for high frequencies of DMI-resistant phenotypes. In contrast, applications of either trifloxystrobin or pyraclostrobin prevented an increase of benzimidazole- or DMI-resistant phenotypes compared with the plots treated with benomyl or difenoconazole, respectively, and decreased frequency of resistance compared with untreated control plots.

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Cercospora beticola Tolerant to Triphenyltin Hydroxide and Resistant to Thiophanate Methyl in North Dakota and Minnesota

Journal of Sugarbeet Research ◽

10.5274/jsbr.35.1.29 ◽

1998 ◽

Vol 35 (1&2) ◽

pp. 29-41 ◽

Cited By ~ 17

Author(s):

L.G. Campbell ◽

G.A. Smith ◽

H.A. Lamey ◽

A.W. Cattanach

Keyword(s):

North Dakota ◽

Cercospora Beticola ◽

Thiophanate Methyl

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Characterization of field-isolates and derived DMI-resistant strains of Cercospora beticola

Mycological Research ◽

10.1017/s0953756203008396 ◽

2003 ◽

Vol 107 (10) ◽

pp. 1178-1188 ◽

Cited By ~ 4

Author(s):

Maddalena Moretti ◽

Anna Arnoldi ◽

Alessandra D'agostina ◽

Gandolfina Farina ◽

Franco Gozzo

Keyword(s):

Cercospora Beticola ◽

Field Isolates ◽

Resistant Strains

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Sensitivity of Cercospora beticola to fungicides in Slovakia

Acta fytotechnica et zootechnica ◽

10.15414/afz.2020.23.03.147-154 ◽

2020 ◽

Vol 23 (3) ◽

pp. 147-154

Author(s):

Kamil Hudec ◽

Milan Mihók ◽

Tibor Roháčik ◽

Ľudovít Mišľan

Keyword(s):

Growth Rate ◽

Sugar Beet ◽

Mode Of Action ◽

Fungicide Resistance ◽

Cercospora Beticola ◽

Active Ingredients ◽

Thiophanate Methyl ◽

Resistant Strains ◽

Pathogen Occurrence ◽

The One

The fungus Cercospora beticola Sacc. is the one of the most important pathogens on the sugar beet. The frequent application of fungicides with the same mode of action increase a risk of development of resistant strains of the pathogen. Occurrence of C. beticola resistant strains has been never researched in Slovakia. In this work, C. beticola isolates were collected from 10 localities of Slovakia and analysed for fungicide resistance in laboratory conditions. Nine fungicides with different mode of action were tested – trifloxystrobin + cyproconazole, kresoxim-methyl + epoxiconazole, azoxystrobin + cyproconazole, thiophanate-methyl + tetraconazole, thiophanate-methyl, prochloraz + propiconazole, picoxystrobin, tetraconazole, and difenoconazole. The results confirmed, that occurrence of fungicide resistance in C. beticola population was established in Slovakia. Different criteria of assessment of fungicide resistance (based on EC50 and on growth rate – inhibition percentage) showed slightly different results, but both criteria confirmed resistant C. beticola strains to thiophanate-methyl, picoxystrobin and difenoconazole. Fields with higher frequency of application of these fungicides significantly supported the development of resistant strains. Assessment of any C. beticola strains have not confirmed reduced sensitivity to active ingredients tetraconazole and prochloraz + propiconazole. The lowest level of risk of fungicide resistance was confirmed in the locality Oslany. It is very important to focus on anti-resistant strategy and reduce of using fungicides on localities, where the occurrence of resistant C. beticola strains was confirmed – Dolné Saliby (thiophanate-methyl and picoxystrobin) and Senec (picoxystrobin and difenoconazole).

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Occurrence of Kasugamycin-resistant strains of Cercospora beticola in sugar beet.

Japanese Journal of Phytopathology ◽

10.3186/jjphytopath.50.637 ◽

1984 ◽

Vol 50 (5) ◽

pp. 637-640 ◽

Cited By ~ 1

Author(s):

Yoshiaki CHIKUO ◽

Toshiya SUGIMOTO ◽

Katsuichi KANZAWA ◽

Hirokatsu UCHINO

Keyword(s):

Sugar Beet ◽

Cercospora Beticola ◽

Resistant Strains

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Fluctuations in Number of Cercospora beticola Conidia in Relationship to Environment and Disease Severity in Sugar Beet

Phytopathology ◽

10.1094/phyto-99-7-0796 ◽

2009 ◽

Vol 99 (7) ◽

pp. 796-801 ◽

Cited By ~ 18

Author(s):

J. Khan ◽

A. Qi ◽

M. F. R. Khan

Keyword(s):

Relative Humidity ◽

Sugar Beet ◽

North Dakota ◽

Disease Severity ◽

Leaf Spot ◽

Forecasting Model ◽

Cercospora Beticola ◽

Disease Forecasting ◽

Cercospora Leaf Spot ◽

Average Temperature

Cercospora leaf spot, caused by Cercospora beticola, is the most damaging foliar disease of sugar beet in Minnesota (MN) and North Dakota (ND). Research was conducted to characterize the temporal progression of aerial concentration of C. beticola conidia in association with the environment and disease severity in sugar beet. In 2003 and 2004, volumetric spore traps were placed within inoculated sugar beet plots to determine daily dispersal of conidia at Breckenridge, MN, and St. Thomas, ND. Plots were rated weekly for disease severity. At both locations, conidia were first collected in early July 2003 and late June in 2004. Peaks of conidia per cubic meter of air were observed with maxima in late August 2003 and in early September 2004 at both locations. Peaks of airborne conidium concentration were significantly correlated with the average temperature of daily hours when relative humidity was greater than 87%. Weekly mean hourly conidia per cubic meter of air was significantly (P < 0.01) associated with disease severity during both years and across locations. This study showed that C. beticola conidial numbers may be used to estimate potential disease severity that, with further research, could be incorporated in a disease forecasting model to rationalize Cercospora leaf spot management.

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