Sensitivity of <i>Phytophthora infestans</i> to mandipropamid and the effect of enforced selection pressure in the field

Cohen, Yigal; Rubin, Evgenia; Hadad, T. El; Gotlieb, Dror; Sierotzki, Helge; Gisi, U.

doi:10.1111/j.1365-3059.2007.01625.x

Cited by 32 publications

(29 citation statements)

References 18 publications

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“…The distribution of isolates in country populations was unimodal and log‐normal (S shape) with a sensitivity range between the most and least sensitive isolate of about 60 for fluazinam and 100 for MPD (Fig. 2) confirming results from earlier years (Cohen et al. 2007).…”

Section: Resultssupporting

confidence: 70%

Changes of Genotype, Sensitivity and Aggressiveness in Phytophthora infestans Isolates Collected in European Countries in 1997, 2006 and 2007

Gisi

Walder²,

Resheat-Eini

et al. 2010

Journal of Phytopathology

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A total of 241 isolates of Phytophthora infestans were collected in 1997, 2006 and 2007 in eight European countries and characterized with molecular markers (simple sequence repeats, SSR genotypes) and phenotypic traits such as sensitivity to fungicides, mating type and aggressiveness. The mating type distribution changed from mainly A1 in 1997 to a majority of A2 in 2007. No resistant isolates were detected for fluazinam and mandipropamid, whereas the proportion of isolates resistant to mefenoxam (MFX) was high and increased over the years. There was no genetic link between mating type and MFX resistance. Aggressiveness (product between lesion expansion and sporulation capacity) was slightly higher for MFX-resistant compared to sensitive isolates and for isolates collected later compared to earlier in the same season. It was about equally high for A1 and A2 types, and for French isolates in 1997 and British isolates in 2007, but lower for French isolates in 2007. Six different SSR genotype families were distinguished. In 1997, populations were dominated by genotype families I and III⁄IV, which significantly declined in 2007 being largely displaced by genotype families II (Ôblue 13Õ type) and V, which are by coincidence mainly A2 MFX resistant and A1 MFX sensitive, respectively. However, mating type and MFX resistance were genetically not linked to SSR genotypes.

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Section: Resultssupporting

confidence: 70%

Changes of Genotype, Sensitivity and Aggressiveness in Phytophthora infestans Isolates Collected in European Countries in 1997, 2006 and 2007

Gisi

Walder²,

Resheat-Eini

et al. 2010

Journal of Phytopathology

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“…infestans (FRAC, 2006). Similarily, Cohen et al (2007) concluded that resistance of Ph. infestans to mandipropamid, another CAA fungicide, occurring in field populations is low.…”

Section: Discussionmentioning

confidence: 82%

“…viticola showed that resistance to CAA fungicides is controlled by recessive nuclear genes and hence resistance is expressed only in homozygous offspring which may require several cycles of sexual reproduction to become fixed and expressed in phenotypically aggressive isolates (Gisi et al ., 2007). Cohen et al. (2007) has commented that where oospores initiate annual epidemics as in the case of grapevine downy mildew CAA‐resistant isolates may develop, whereas in potato‐late blight populations, oospore inoculum may be less important and consequently CAA resistance will not emerge among field populations.…”

Section: Discussionmentioning

confidence: 99%

Resistance of Pseudoperonospora cubensis to flumorph on cucumber in plastic houses

et al. 2007

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Plastic-house experiments were conducted over a 2-year period to estimate the effects of successive applications of flumorph or a mixture of flumorph with mancozeb to cucumber plants on selection for flumorph resistance in the downy mildew oomycete, Pseudoperonospora cubensis . Application of flumorph alone favoured the selection of resistant isolates of Ps. cubensis . Resistant populations were detected at a frequency of 2·5% after six successive applications of flumorph alone in a plastic house in 2004. Resistant isolates were also detected (4·8%) after eight successive applications of the mixture of flumorph and mancozeb in 2004, although the mixture gave significantly better disease control than flumorph alone and produced a slight delay in the development of resistance. In a second cucumber crop in the same plastic houses in 2004, the frequency of resistant isolates increased to 100% after three successive applications of flumorph or four of flumorph + mancozeb. Under laboratory conditions, most flumorph-resistant isolates showed high levels of resistance and their levels of pathogenicity and sporulation were as high as that of wild-type isolates. Flumorph showed cross-resistance with dimethomorph and iprovalicarb, but not with azoxystrobin, cyazofamid, cymoxanil or metalaxyl. These studies suggest a high risk for the occurrence of resistance to flumorph in Ps. cubensis in cucumber crops under plastic-house conditions.

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“…It appeared that mandipropamid inhibited mycelial growth and sporangial production of P. capsici at lower concentrations compared with suppression of zoospore germination. Cohen et al (5) evaluated the effect of mandipropamid on mycelial growth of P. infestans, causal agent of potato late blight. All isolates tested were sensifive to this compound, with EC50 values of 0.02 to 2.98 |jg/ml.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of Phytophthora capsici on Vegetable Crops in Georgia to Mandipropamid, Dimethomorph, and Cyazofamid

Jackson

Yin

2012

Plant Disease

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Jackson, K. L., Yin, J., and Ji, P. 2012. Sensitivity of Phytophthora capsici on vegetable crops in Georgia to mandipropamid, dimethomorph, and cyazofamid. Plant Dis. 96:1337-1342. Phytophthora blight, caused by Phytophthora capsici, is a seriotis disease in vegetable production, and selective use of fungicides continues to be a significant component of disease management programs. The effect of three chemical compounds-mandipropamid, dimethomorph, and cyazofamid-on asexual stages of P. capsici collected from bell pepper and cucurbits in Georgia was assessed in this study. Forty isolates of P. capsici were determined to be sensitive to mandipropamid and dimethomorph based on mycelial growth, zoospore germination, and sporangial production. Concentrations that were 50% effsctive (EC50 values) of mandipropamid that inhibited mycelial growth, zoospore germination, and sporangial production of the isolates averaged 0.03, 5.70, and 0.02 (ig/ml, respectively. EC50 values of dimethomorph in inhibiting mycelial growth, zoospore germination, and sporangial production averaged 0.24, 0.10, and 0.46 Mg/ml, respectively. The majority of isolates were either resistant or intermediateiy sensitive to cyazofamid at 500 pg/ml or lower concentrations based on mycelial growth or sporangial production, although all the isolates were sensitive to this compound based on zoospore germination, with an average EC50 of 0.04 |jg/ml. The results indicated that P. capsici populations in Georgia have not developed resistance to mandipropamid and cimethomorph whereas, for the majority of the isolates, certain asexual stages were resistant to cyazofamid.

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Sensitivity of Phytophthora infestans to mandipropamid and the effect of enforced selection pressure in the field

Abstract: ) doses of MPD on mixed isolates of P. infestans produced no isolates resistant to the compound. The results of this study indicate that the probability of a buildup of resistant sub-populations of P. infestans to mandipropamid in the field is low.

Cited by 32 publications

References 18 publications

Changes of Genotype, Sensitivity and Aggressiveness in Phytophthora infestans Isolates Collected in European Countries in 1997, 2006 and 2007

Changes of Genotype, Sensitivity and Aggressiveness in Phytophthora infestans Isolates Collected in European Countries in 1997, 2006 and 2007

Resistance of Pseudoperonospora cubensis to flumorph on cucumber in plastic houses

Sensitivity of Phytophthora capsici on Vegetable Crops in Georgia to Mandipropamid, Dimethomorph, and Cyazofamid

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