A Quantitative PCR Assay for Detection and Quantification of .

is an ascomycete that has been isolated from a broad range of plant hosts, including hop ( L.), where it acts as a causal agent of Fusarium canker, a disease that can impact cone quality and yield in severe cases. Current diagnostic methods rely on isolation of the fungus from plant tissue, a time- and resource-intensive process with limited sensitivity, complicated by the potential presence of other spp.

Temperature Influences on Powdery Mildew Susceptibility and Development in the Hop Cultivar Cascade.

The hop cultivar 'Cascade' possesses partial resistance to powdery mildew () that can be overcome by recently emerged, virulent isolates of the fungus. Given that hop is a long-lived perennial and that brewers still demand Cascade, there is a need to better understand factors that influence the development of powdery mildew on this cultivar. Growth chamber experiments were conducted to quantify the effect of constant, transient, and fluctuating temperature on Cascade before, concurrent to, and after inoculation as contrasted with another powdery mildew-susceptible cultivar, 'Symphony'.

Fungicide Physical Mode of Action: Impacts on Suppression of Hop Powdery Mildew.

Understanding of the physical mode of action of fungicides allows more efficient and effective application and can increase disease control. Greenhouse and field studies were conducted to explore the preinfection and postinfection duration and translocative properties of fungicides commonly used to control hop powdery mildew, caused by . In greenhouse studies, applications made 24 h before inoculation were almost 100% effective at suppressing powdery mildew, regardless of the fungicide evaluated.

Black Leg and Chlorotic Leaf Spot Occurrence on Brassicaceae Crop and Weed Hosts.

Black leg (caused by and ) and chlorotic leaf spot (caused by ) are economically important fungal diseases of Brassicaceae crops. Surveys of seed fields and weed hosts were conducted to understand the distribution and prevalence of these diseases in Oregon after black leg and chlorotic leaf spot outbreaks occurred in Brassicaceae crops in 2014. Postharvest black leg ratings were conducted in seed fields of canola, forage rape, and turnip in 2015 and 2016.

High Levels of Insensitivity to Phosphonate Fungicides in .

Phosphonate (phosphite; HPO) is fungicidal against oomycetes and certain other organisms. The Fungicide Resistance Action Committee has deemed phosphonate to be at low risk of resistance development, and reduced sensitivity to phosphonate has been reported only occasionally in plant pathogens. Reduced sensitivity to the fungicide fosetyl-Al was documented in the hop downy mildew pathogen, , in the early 2000s, but disease caused by insensitive isolates could still be managed commercially if the fungicide rate was doubled from 2.

Population Diversity and Structure of in the Pacific Northwestern United States and Other Populations.

Powdery mildew, caused by , is one of the most important diseases of hop. The disease was first reported in the Pacific Northwestern United States, the primary hop-growing region in this country, in the mid-1990s. More recently, the disease has reemerged in newly planted hopyards of the eastern United States, as hop production has expanded to meet demands of local craft brewers.

Susceptibility of Hop Crown Buds to Powdery Mildew and its Relation to Perennation of Podosphaera macularis.

In the Pacific Northwestern United States, the hop powdery mildew fungus, Podosphaera macularis, survives overwintering periods in association with living host tissue because the ascigerious stage of the pathogen is not known to occur in this region. Field experiments were conducted over a 5-year period to describe the overwintering process associated with crown bud infection and persistence of P. macularis.