First Report of Twig Dieback Caused by on Highbush Blueberry in the Continental United States.

Highbush blueberry (Vaccinium corymbosum) is an important fruit crop for pick-your-own agritourism farms in the Midwest. Declining or diseased plants are a major concern for pick-your-own farms, as consumers prioritize healthy plants and organic practices (Norby and Retallick 2012). In August 2023, leaf spot and dieback symptoms were observed sporadically on the current year's growth throughout an organic berry agritourism farm in Eastern Iowa.

Identification of a reduced rate combination of a plant growth inhibitor with a plant defense inducer for the management of the shoot blight phase of fire blight.

The secondary shoot blight phase of fire blight is a critical component of disease epidemics in apples, pears, and other Rosaceae family plants with infection occurring at the tips of vigorously growing branches. Shoot blight infections are exacerbated in modern high-density apple plantings, where growers emphasize maximizing tree growth to recapture planting costs and increase yields of high-quality fruit. The overarching goal of this study was to develop new strategies for shoot blight management that do not impact the growth and yield of young apple trees.

Identification of streptomycin-resistant in Iowa.

Erwinia amylovora is a bacterial pathogen that causes fire blight, an important disease in apples and pears. Applying the antibiotic streptomycin during the phenological bloom stage is considered the most effective management tactic for fire blight. Though streptomycin-resistant (SmR) E.

An In-Depth Evaluation of Powdery Mildew Hosts Reveals One of the World's Most Common and Widespread Groups of Fungal Plant Pathogens.

Powdery mildews are highly destructive fungal plant pathogens that have a significant economic impact on both agricultural and ecological systems worldwide. The intricate relationship between powdery mildews and their host plants has led to cospeciation. In this study, we conducted an extensive evaluation of powdery mildew hosts to provide an updated understanding of the host ranges and distributions of these fungi.

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.

The RNA-Binding Protein ProQ Impacts Exopolysaccharide Biosynthesis and Second Messenger Cyclic di-GMP Signaling in the Fire Blight Pathogen Erwinia amylovora.

Erwinia amylovora is a plant-pathogenic bacterium that causes fire blight disease in many economically important plants, including apples and pears. This bacterium produces three exopolysaccharides (EPSs), amylovoran, levan, and cellulose, and forms biofilms in host plant vascular tissues, which are crucial for pathogenesis. Here, we demonstrate that ProQ, a conserved bacterial RNA chaperone, was required for the virulence of E.

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 Novel Signaling Pathway Connects Thiamine Biosynthesis, Bacterial Respiration, and Production of the Exopolysaccharide Amylovoran in .

is a plant pathogen causing necrotrophic fire blight disease of apple, pear, and other rosaceous plants. This bacterium colonizes host vascular tissues via the production of exopolysaccharides (EPSs) including amylovoran. It is well-established that the nearly ubiquitous plasmid pEA29 of is an essential virulence factor, but the underlying mechanism remains uncharacterized.

Genetic Dissection of the Disease Cycle.

Fire blight, caused by the bacterial phytopathogen , is an economically important and mechanistically complex disease that affects apple and pear production in most geographic production hubs worldwide. We compile, assess, and present a genetic outlook on the progression of an infection in the host. We discuss the key aspects of type III secretion-mediated infection and systemic movement, biofilm formation in xylem, and pathogen dispersal via ooze droplets, a concentrated suspension of bacteria and exopolysaccharide components.

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.

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.