Allele-specific detection methods for QoI fungicide resistant Erysiphe necator in vineyards
Grapevine powdery mildew (GPM), caused by the fungus Erysiphe necator, is a constant threat to worldwide production of grapes, requiring repeated use of fungicides for management. The frequent fungicide applications have resulted in resistance to commonly used quinone outside inhibitor (QoIs) fungicides and the resistance is associated with single nucleotide polymorphisms (SNPs) in the mitochondrial cytochrome b gene (cytb). In this study, we attempted to detect the most common SNP causing a glycine to alanine substitution at amino acid position 143 (i.e., G143A) in the cytb protein, to track this resistance using allele-specific TaqMan probe- and digital droplet PCR-based assays. Specificity and sensitivity of these assays showed that these two assays could discriminate SNPs and were effective on mixed samples. These diagnostic assays were implemented to survey E. necator samples collected from leaf and air samples from California and Oregon grape growing regions. Sequencing of PCR amplicons and phenotyping of isolates also revealed that these assays accurately detected each allele (100% agreement) and there was an absolute agreement between the presence/absence of the G143A mutation and resistance to QoIs in the E. necator sampled. These results indicate that the developed diagnostic tools will help growers make informed decisions on fungicide selections and applications, which in turn, will facilitate GPM disease management and improve grape production systems.
Citation: Miles, T.D., Neill, T.M., Colle, M., Warneke, B, Robinson, G., Sterigiopoulus, I. and Mahaffee, W.F. 2021. Allele-specific detection methods for QoI fungicide resistant Erysiphe necator in vineyards. Plant Disease 105: 175-182.
Utilizing dynamic parallelism in CUDA to accelerate a 3D red-black successive over relaxation wind-field solver
QES-Winds is a fast-response wind modeling platform for simulating high-resolution mean wind fields for optimization and prediction. The code uses a variational analysis technique to solve the Poisson equation for Lagrange multipliers to obtain a mean wind field and GPU parallelization to accelerate the numerical solution of the Poisson equation. QES-Winds benefits from CUDA dynamic parallelism (launching the kernel from the GPU) to speed up calculations by a factor of 128 compared to the serial solver for a domain with 145 million cells. The dynamic parallelism enables QES-Winds to calculate mean velocity fields for domains with sizes of 10 km2 and horizontal resolutions of 1-3 m in under 1 min. As a result, QES-Winds is a numerical code suitable for computing high-resolution wind fields on large domains in real time, which can be used to model a wide range of real-world problems including wildfires and urban air quality.
Citation: Bozorgmehr, B., Willemsen, P., Gibbs, J., Stoll, R., Kim, J., & Pardyjak, E. 2021. Utilizing dynamic parallelism in CUDA to accelerate a 3D red-black successive over relaxation wind-field solver. Environmental Modelling & Software: with Environment Data News., 137.
Assessing the United States grape industry’s understanding of fungicide resistance mitigation practices
In 2019, a national survey of 252 members of the USA grape industry from 20 USA states assessed knowledge perception of fungicide resistance management, application of that knowledge to vineyard practices, and knowledge acquisition sources. Overall, respondents demonstrated clear understanding of resistance management practices. The specific distribution of responses was influenced by the respondent’s job role, duration of industry experience, and their farming operation size. Nationally, respondents were moderately familiar with the acronym FRAC (Fungicide Resistance Action Committee), with nearly 75% indicating they could identify the FRAC code of a fungicide. They felt moderately competent they could design a fungicide program that adhered to resistance management principles. Respondents identified fungicide resistance as a serious problem nationally, and as a moderate problem in their own vineyards. They ranked practices that include rotating fungicides of different FRAC codes, avoiding multiple sequential applications of the same trade name or FRAC code, tank mixing with different FRAC codes, using multisite products in a spray program, routine sprayer maintenance and calibration, and good canopy management as very to extremely important in managing fungicide resistance; whereas practices such as rotating between trade names and tank mixing different trade names ranked slightly important. Respondents identified university-based Extension programs as the primary information resource for fungicide efficacy and fungicide stewardship (resistance management). In order to maximize potential impact, these results suggest that future educational efforts should be aimed at improving practices for fungicide resistance stewardship and should align with the knowledge base and demographic factors of the target audience particularly their job role, experience and size of operation.
Citation: Oliver, C., M. Cooper, M. Lewis-Ivey, P. Brannen, T. Miles, W. Mahaffee, and M. Moyer. 2021. Assessing the United States grape industry’s understanding of fungicide resistance mitigation practices. Am. J. Enol. Vitic.72 (2). In press, April 2021.