Multisite Field Evaluation of Bacteriophages for Fire Blight Management: Incorporation of Ultraviolet Radiation Protectants and Impact on the Apple Flower Microbiome.

Fire blight, a disease of pome fruits caused by the bacterium , has become increasingly difficult to manage after the emergence of streptomycin-resistant strains. Alternative antibiotics and copper are available; however, these chemicals have use restrictions in some countries and also can carry risks of phytotoxicity. Therefore, there is growing interest in biological-based management options, with bacteriophage (phages) showing promise, as these naturally occurring pathogens of bacteria are easy to isolate and grow.

Evaluation of Plant Defense Inducers and Plant Growth Regulators for Fire Blight Management Using Transcriptome Studies and Field Assessments.

Fire blight, caused by , is a destructive disease of pome fruit trees. In the United States, apple and pear growers rely on applications of copper and antibiotics during bloom to control fire blight, but such methods have already led to regional instances of resistance. In this study, we used transcriptome analyses and field trials to evaluate the effectiveness of three commercially available plant defense elicitors and one plant growth regulator for fire blight management.

Resistance to Boscalid, Fluopyram and Fluxapyroxad in from Michigan (U.S.A.): Molecular Characterization and Assessment of Practical Resistance in Commercial Cherry Orchards.

Management of cherry leaf spot disease, caused by the fungus , with succinate dehydrogenase inhibitor (SDHI) fungicides has been ongoing in Michigan tart cherry orchards for the past 17 years. After boscalid-resistant were first isolated from commercial orchards in 2010, premixes of SDHI fungicides fluopyram or fluxapyroxad with a quinone outside inhibitor were registered in 2012. Here, we report widespread resistance to fluopyram (Fluo), fluxapyroxad (Flux), and boscalid (Bosc) in commercial orchard populations of in Michigan from surveys conducted between 2016 and 2019.

A Method for the Examination of SDHI Fungicide Resistance Mechanisms in Phytopathogenic Fungi Using a Heterologous Expression System in .

Succinate dehydrogenase inhibitors (SDHIs) are a class of broad-spectrum fungicides used for management of diseases caused by phytopathogenic fungi. In many cases, reduced sensitivity to SDHI fungicides has been correlated with point mutations in the and target genes that encode components of the succinate dehydrogenase complex. However, the genetic basis of SDHI fungicide resistance mechanisms has been functionally characterized in very few fungi.

Effect of Kasugamycin, Oxytetracycline, and Streptomycin on In-orchard Population Dynamics of on Apple Flower Stigmas.

We assessed the effect of three antibiotics (streptomycin, oxytetracycline, and kasugamycin) on populations of the fire blight pathogen on apple flower stigmas during three field seasons. Application timing relative to presence on flower stigmas had little impact on population dynamics and subsequent disease incidence. Although populations on water-treated flowers increased to 10 cfu flower after 4 to 5 days during each experiment, the antibiotics streptomycin and kasugamycin caused statistically significant reductions in stigma populations by as many as 4 to 5 logs over a 4- to 5-day period during two of the three experiments.

Survey and Genetic Analysis of Demethylation Inhibitor Fungicide Resistance in From Michigan Orchards.

Resistance to sterol demethylation inhibitor (DMI) fungicides in , causal agent of brown rot of stone fruit, has been reported in the southeastern and eastern United States and in Brazil. DMI resistance of some isolates, in particular those recovered from the southeastern United States, is associated with a sequence element termed "Mona" that causes overexpression of the cytochrome demethylase target gene . In this study, we conducted statewide surveys of Michigan stone fruit orchards from 2009 to 2011 and in 2019, and we determined the sensitivity to propiconazole of a total of 813 isolates of .

Draft Genome Sequence Resource for , the Cherry Leaf Spot Pathogen.

is the causal agent of cherry leaf spot (CLS), the most important disease of tart cherry in the Midwestern United States. Infection of leaves by leads to premature defoliation, which places trees at heightened risk of winter injury and death. Current management of CLS relies primarily on the application of three important fungicide classes, quinone outside inhibitors, sterol demethylation inhibitors, and succinate dehydrogenase inhibitors.

Boscalid Resistance in : Distribution, Effect on Field Efficacy, and Molecular Characterization.

Cherry leaf spot (CLS), caused by the fungus , is a major disease of tart cherry ( L.) trees, leading to early defoliation that results in uneven ripening and poor fruit quality in the current season, reduced fruit set in the following season, and increased potential for winter injury and tree death. Pristine (BASF Corporation, Research Triangle Park, NC), a commonly used fungicide for CLS management in Michigan, is a premix of boscalid, a succinate dehydrogenase inhibitor, and pyraclostrobin, a quinone outside inhibitor.

Microbiological Examination of Erwinia amylovora Exopolysaccharide Ooze.

Fire blight, caused by the pathogen Erwinia amylovora, is the most devastating bacterial disease of pome fruit in North America and worldwide. The primary method of dispersal for E. amylovora is through ooze, a mass of exopolysaccharides and bacterial cells that is exuded as droplets from infected host tissue.