Multiple routes to fungicide resistance: Interaction of Cyp51 gene sequences, copy number and expression.

We examined the molecular basis of triazole resistance in Blumeria graminis f. sp. tritici (wheat mildew, Bgt), a model organism among powdery mildews.

Identification of a Novel Allele Conferring a Wide Spectrum of Resistance to Powdery Mildew in Wheat Accession PI 351817.

Powdery mildew is caused by the highly adaptive biotrophic fungus f. sp. infecting wheat worldwide.

Effects of Host and Weather Factors on the Growth Rate of Septoria nodorum Blotch Lesions on Winter Wheat.

Septoria nodorum blotch (SNB), caused by , is a major disease of winter wheat that occurs frequently in the central and southeastern United States. Quantitative resistance to SNB in wheat is determined by various disease resistance components and their interaction with environmental factors. A study was conducted in North Carolina from 2018 to 2020 to characterize SNB lesion size and growth rate and to quantify the effects of temperature and relative humidity on lesion expansion in winter wheat cultivars with different levels of resistance.

Optimal Timing of Fungicide Application to Manage Fusarium Head Blight in Winter Barley.

Fusarium head blight (FHB) is among the chief threats to profitable barley production, and fungicide applications are one of two main strategies for reducing FHB damage to barley crops. However, there is very little published information on optimal timing of such applications. A 4-year field study was conducted with winter barley in Raleigh, North Carolina, to compare three timings for fungicide application: 50% spike emergence (Zadoks growth stage or GS 55), 100% spike emergence (GS 59), and 6 days after GS 59.

Two pathogen loci determine Blumeria graminis f. sp. tritici virulence to wheat resistance gene Pm1a.

Blumeria graminis f. sp. tritici (Bgt) is a globally important fungal pathogen of wheat that can rapidly evolve to defeat wheat powdery mildew (Pm) resistance genes.

Evaluation of a Model for Predicting Onset of Septoria nodorum Blotch in Winter Wheat.

Prediction models that aid growers in making decisions on timing of fungicide application are important components of integrated management programs for several foliar diseases of wheat. The risk of Septoria nodorum blotch (caused by ) onset in winter wheat has been reported to be influenced by location, amount of wheat residue in the field, and cumulative daily infection values 2 weeks prior to day of year (DOY) 102. A model previously developed based on these predictor variables was evaluated for its ability to predict disease onset under field conditions.

Global genomic analyses of wheat powdery mildew reveal association of pathogen spread with historical human migration and trade.

The fungus Blumeria graminis f. sp. tritici causes wheat powdery mildew disease.

Accounting for heading date gene effects allows detection of small-effect QTL associated with resistance to Septoria nodorum blotch in wheat.

In humid and temperate areas, Septoria nodorum blotch (SNB) is a major fungal disease of common wheat (Triticum aestivum L.) in which grain yield is reduced when the pathogen, Parastagonospora nodorum, infects leaves and glumes during grain filling. Foliar SNB susceptibility may be associated with sensitivity to P.

Infection timing affects Fusarium poae colonization of bread wheat spikes and mycotoxin accumulation in the grain.

Background: Fusarium poae is one of the most common Fusarium head blight (FHB) causal agents in wheat. This species can biosynthesize a wide range of mycotoxins, in particular nivalenol (NIV). In FHB epidemiology, infection timing is important for disease occurrence, kernel development, symptom appearance and mycotoxin accumulation in grain.

Sensitivity of the U.S. Wheat Powdery Mildew Population to Quinone Outside Inhibitor Fungicides and Determination of the Complete f. sp. Cytochrome Gene.

Wheat powdery mildew, caused by f. sp. , is managed primarily with cultivar resistance and foliar fungicides.

spp. Associated with Root Rot and Stunting of Winter Wheat in North Carolina.

In eastern North Carolina, mild to severe stunting and root rot have reduced yields of winter wheat, especially during years with abundant rainfall. Causal agents of root rot of wheat in this region were previously identified as , , and . To investigate species prevalence, 114 isolates of were obtained from symptomatic wheat plants collected in eight counties.

Timing of Susceptibility to Fusarium Head Blight in Winter Wheat.

The duration of wheat susceptibility to infection has implications for risk forecasting, fungicide timing, and the likelihood that visible kernel damage may underpredict deoxynivalenol (DON) contamination. A field experiment was conducted to explore the impact of varying infection timings on Fusarium head blight (FHB) development in winter wheat. Trials in four successive years (2010 to 2013) in North Carolina utilized one susceptible and one moderately resistant cultivar possessing similar maturity, stature, and grain quality.

Regional and field-specific differences in Fusarium species and mycotoxins associated with blighted North Carolina wheat.

Worldwide, while Fusarium graminearum is the main causal species of Fusarium head blight (FHB) in small-grain cereals, a diversity of FHB-causing species belonging to different species complexes has been found in most countries. In the U.S.

Role of Effector-Sensitivity Gene Interactions and Durability of Quantitative Resistance to Septoria Nodorum Blotch in Eastern U.S. Wheat.

Important advances have been made in understanding the relationship of necrotrophic effectors () and host sensitivity () genes in the -wheat pathosystem. Yet much remains to be learned about the role of these interactions in determining wheat resistance levels in the field, and there is mixed evidence on whether breeding programs have selected against genes due to their role in conferring susceptibility. SNB occurs ubiquitously in the U.

Managing a Destructive, Episodic Crop Disease: A National Survey of Wheat and Barley Growers' Experience With Fusarium Head Blight.

The main techniques for minimizing Fusarium head blight (FHB, or scab) and deoxynivalenol in wheat and barley are well established and generally available: planting of moderately FHB-resistant cultivars, risk monitoring, and timely use of the most effective fungicides. Yet the adoption of these techniques remains uneven across the FHB-prone portions of the U.S.

Sensitivity of the U.S. f. sp. Population to Demethylation Inhibitor Fungicides.

Wheat powdery mildew, caused by f. sp. , is managed in the United States with cultivar resistance and foliar fungicides.

Local adaptation drives the diversification of effectors in the fungal wheat pathogen Parastagonospora nodorum in the United States.

Filamentous fungi rapidly evolve in response to environmental selection pressures in part due to their genomic plasticity. Parastagonospora nodorum, a fungal pathogen of wheat and causal agent of septoria nodorum blotch, responds to selection pressure exerted by its host, influencing the gain, loss, or functional diversification of virulence determinants, known as effector genes. Whole genome resequencing of 197 P.

Managing Fusarium Head Blight in Winter Barley With Cultivar Resistance and Fungicide.

Although there has been research on managing Fusarium head blight (FHB) in spring barley, little has been published on cultivar resistance and optimal fungicide timing for FHB management in winter barley. A 3-year (2015 to 2017) field experiment was conducted to measure FHB resistance of winter barley varieties, gauge the potential benefit from a fungicide, and help determine the optimal timing for fungicide application. The split-plot experiment took place in a misted, inoculated nursery in Raleigh, North Carolina using main plots of four winter barley cultivars (Atlantic, Endeavor, Nomini, and Thoroughbred).

Characterization of Pm65, a new powdery mildew resistance gene on chromosome 2AL of a facultative wheat cultivar.

A new powdery mildew resistance gene that can be readily used in wheat breeding, Pm65, was identified in the facultative wheat cultivar Xinmai 208 and mapped to the terminal region of chromosome 2AL. Wheat powdery mildew, a widely occurring disease caused by the biotrophic fungus Blumeriagraminis f. sp.

Durability of Quantitative Resistance in Crops: Greater Than We Know?

Quantitative resistance (QR) to crop diseases has usually been much more durable than major-gene, effector-triggered resistance. It has been observed that the effectiveness of some QR has eroded as pathogens adapt to it, especially when deployment is extensive and epidemics occur regularly, but it generally declines more slowly than effector-triggered resistance. Changes in aggressiveness and specificity of diverse pathogens on cultivars with QR have been recorded, along with experimental data on fitness costs of pathogen adaptation to QR, but there is little information about molecular mechanisms of adaptation.

Virulence of Egyptian Blumeria graminis f. sp. tritici Population and Response of Egyptian Wheat Cultivars.

Powdery mildew, caused by Blumeria graminis (DC.) Speer f. sp.

Understanding Yield Loss and Pathogen Biology to Improve Disease Management: Septoria Nodorum Blotch - A Case Study in Wheat.

The estimated potential yield losses caused by plant pathogens is up to 16% globally and most research in plant pathology aims to reduce yield loss in our crops directly or indirectly. Yield losses caused by a certain disease depend not only on disease severity, but also on the weather factors, the pathogen's aggressiveness, and the ability of the crop to compensate for reduced photosynthetic area. The yield loss-disease relationship in a certain host-pathogen system might therefore change from year to year, making predictions for yield loss very difficult at the regional or even at the farmer's level.

Characterization of Pm63, a powdery mildew resistance gene in Iranian landrace PI 628024.

A new powdery mildew resistance gene conferring a wide spectrum of resistance to Bgt isolates in the USA, Pm63 , was identified in Iranian wheat landrace PI 628024 and mapped to the terminal region of the long arm of chromosome 2B. Powdery mildew is a globally important wheat disease causing severe yield losses, and host resistance is the preferred strategy for managing this disease. The objective of this study was to characterize a powdery mildew resistance gene in Iranian landrace PI 628024, which exhibited a wide spectrum of resistance to representative Blumeria graminis f.