Use of Two- and Three-Way Mixtures to Prevent Buildup of Resistance to Phenylamide Fungicides in<i>Phytophthora</i>and<i>Plasmopara</i>

Samoucha, Y.

doi:10.1094/phyto-77-1405

Cited by 29 publications

(18 citation statements)

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“…Resistance is often attributed to frequent use of antimicrobial compounds of the same class. Combinations of mixtures with different modes of actions can reduce the probability of resistance development, because a pathogen would have to develop resistance to all components in a mixture simultaneously (64). In our experiments focused on investigating the interaction of culture filtrates of B. subtilis and B. amyloliquefaciens, we did not detect any synergism, which is consistent with our LC-MS analyses showing that isolates of both B. subtilis and B. amyloliquefaciens produced primarily fengycins, which have previously been suggested to inhibit Alternaria (29,30).…”

Section: Discussionmentioning

confidence: 99%

Ex Vivo Application of Secreted Metabolites Produced by Soil-Inhabiting Bacillus spp. Efficiently Controls Foliar Diseases Caused by Alternaria spp

Ali

El-Sayed

Patel

et al. 2016

Appl Environ Microbiol

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Bacterial biological control agents (BCAs) are largely used as live products to control plant pathogens. However, due to variable environmental and ecological factors, live BCAs usually fail to produce desirable results against foliar pathogens. In this study, we investigated the potential of cell-free culture filtrates of 12 different bacterial BCAs isolated from flower beds for controlling foliar diseases caused by Alternaria spp. In vitro studies showed that culture filtrates from two isolates belonging to Bacillus subtilis and Bacillus amyloliquefaciens displayed strong efficacy and potencies against Alternaria spp. The antimicrobial activity of the culture filtrate of these two biological control agents was effective over a wider range of pH (3.0 to 9.0) and was not affected by autoclaving or proteolysis. Comparative liquid chromatography-mass spectrometry (LC-MS) analyses showed that a complex mixture of cyclic lipopeptides, primarily of the fengycin A and fengycin B families, was significantly higher in these two BCAs than inactive Bacillus spp. Interaction studies with mixtures of culture filtrates of these two species revealed additive activity, suggesting that they produce similar products, which was confirmed by LC-tandem MS analyses. In in planta pre-and postinoculation trials, foliar application of culture filtrates of B. subtilis reduced lesion sizes and lesion frequencies caused by Alternaria alternata by 68 to 81%. Taken together, our studies suggest that instead of live bacteria, culture filtrates of B. subtilis and B. amyloliquefaciens can be applied either individually or in combination for controlling foliar diseases caused by Alternaria species. Many species in the genus Alternaria cause significant yield and quality losses in food and ornamental crops (1). These species primarily attack aerial plant parts, including foliage, fruits, and stems, and cause a variety of symptoms ranging from necrotic leaf spots to enlarged blighted shoots, eventually resulting in defoliation and loss in yield and quality. Alternaria diseases could be managed with a combination of cultural practices, fungicides, and, if available, genetic resistance. Since many crop cultivars lack sufficient resistance to Alternaria spp., fungicide sprays are the primary means of controlling Alternaria diseases (1). However, loss in the efficacy of several commonly used fungicides for controlling Alternaria spp. has been reported (2-6). Loss of effective fungicides requires discovery and development of new and safe alternative chemicals. Although fungicides with newer chemistry are promising, their introduction into crop production systems is slow, and resistant field isolates of the pathogen usually appear very quickly, within a few seasons of the introduction of a new fungicide (5, 7, 8). As with many other plant pathogens, in most cases fungicide resistance in Alternaria spp. has been attributed to single-site mutations in the target genes (see, e.g., references 9, 10, and 11). Therefore, finding multisite-acting fungicides t...

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Section: Discussionmentioning

confidence: 99%

Ex Vivo Application of Secreted Metabolites Produced by Soil-Inhabiting Bacillus spp. Efficiently Controls Foliar Diseases Caused by Alternaria spp

Ali

El-Sayed

Patel

et al. 2016

Appl Environ Microbiol

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“…Thus, mancozeb appeared to be an ineffective partner for flumorph to delay the development of resistance to the latter. Previous reports also suggested that two‐way mixtures of a systemic (site‐specific) and protective (surface, multi‐site) fungicide still have high selection pressure (Davidse et al ., 1983; Samoucha & Cohen, 1985; Samoucha & Gisi, 1987; Genet et al ., 2006); only three‐way prepacked mixtures were significantly more efficient at both controlling disease and delaying resistance buildup (Skylakakis, 1981; Samoucha & Gisi, 1987).…”

Section: Discussionmentioning

confidence: 99%

“…In each plastic house, approximately 30 single-lesion isolates from 30 leaves were randomly sampled for sensitivity tests. Subsequently, resistance was monitored after every two spray applications using a bioassay described previously (Samoucha & Gisi, 1987). Briefly, 20 -30 new infected leaves with sporulating lesions were sampled randomly from each plastic house.…”

Section: Determination Of Resistance Frequencymentioning

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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“…Experimental data relating to the effectiveness of mixture and rotation strategies are limited. Growth-room and plastic-tunnel studies on Phytophthora infestans, showed that applications of mixtures of a phenylamide fungicide with mancozeb or mancozeb plus cymoxanil decreased the build-up of phenylamide resistance, compared with phenylamide alone (Staub and Sozzi, 1984;Samoucha and Gisi, 1987). Selection for QoI resistance in Plasmopara viticola was delayed by a mixture with folpet, fosetylaluminium or mancozeb (Genet et al, 2006).…”

Section: Do Not Use the Product Exclusivelymentioning

confidence: 99%

Industry Views of Monitoring and Mitigation of Herbicide Resistance

Soteres¹,

Peterson²

2015

Weed sci.

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Use of Two- and Three-Way Mixtures to Prevent Buildup of Resistance to Phenylamide Fungicides inPhytophthoraandPlasmopara

Cited by 29 publications

References 0 publications

Ex Vivo Application of Secreted Metabolites Produced by Soil-Inhabiting Bacillus spp. Efficiently Controls Foliar Diseases Caused by Alternaria spp

Ex Vivo Application of Secreted Metabolites Produced by Soil-Inhabiting Bacillus spp. Efficiently Controls Foliar Diseases Caused by Alternaria spp

Resistance of Pseudoperonospora cubensis to flumorph on cucumber in plastic houses

Industry Views of Monitoring and Mitigation of Herbicide Resistance

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