Chemical management strategies for halo blight of hop and in vitro sensitivity of populations to various fungicide classes.

Halo blight of hop, caused by Diaporthe humulicola, has increased in eastern North America since 2018. When left untreated, the disease can cause yield loss ranging from 17-56%. Currently, there are no fungicides registered for use on halo blight of hop.

Managing fruit rot diseases of .

Blueberry is an important perennial fruit crop with expanding consumption and production worldwide. Consumer demand for blueberries has grown due to the desirable flavor and numerous health benefits, and fresh market production in the U.S.

Fungicide resistance in and identification of species associated with blueberry in Michigan.

Botrytis blossom blight and fruit rot, caused by , is a significant threat to blueberries, potentially resulting in substantial economic losses if not effectively managed. Despite the recommendation of various cultural and chemical practices to control this pathogen, there are widespread reports of fungicide resistance, leading to decreased efficacy. This study aimed to characterize the resistance profile of isolated from blighted blossoms and fruit in 2019, 2020 and 2022 ( = 131, 40, and 37 for the respective years).

Detection of in Air Samples by Quantitative PCR.

Detection and quantification of pathogen propagules in the air or other environmental samples is facilitated by culture-independent assays. We developed a quantitative PCR assay for the hop powdery mildew fungus, , for detection of the organism from air samples. The assay uses primers and a TaqMan probe designed to target species-specific sequences in the 28S large subunit of the nuclear ribosomal DNA.

It's a Trap! Part II: An Approachable Guide to Constructing and Using Rotating-Arm Air Samplers.

An increasing number of researchers are looking to understand the factors affecting microbial dispersion but are often limited by the costs of commercially available air samplers. Some have reduced these costs by designing self-made versions; however, there are no published sampler designs, and there is limited information provided on the actual construction process. Lack of appropriate reference material limits the use of these self-made samplers by many researchers.

It's a Trap! Part I: Exploring the Applications of Rotating-Arm Impaction Samplers in Plant Pathology.

Although improved knowledge on the movement of airborne plant pathogens is likely to benefit plant health management, generating this knowledge is often far more complicated than anticipated. This complexity is driven by the dynamic nature of environmental variables, diversity among pathosystems that are targeted, and the unique needs of each research group. When using a rotating-arm impaction sampler, particle collection is dependent on the pathogen, environment, research objectives, and limitations (monetary, environmental, or labor).

First Report of Infecting Hop () in Michigan.

In July of 2020, a hop (Humulus lupulus L.) grower in Berrien County, Michigan submitted 'Chinook' leaf samples to MSU Plant & Pest Diagnostics. The leaves were covered in small, tan colored lesions, with a small chlorotic halo with an approximate diameter of 5 mm.

First report of stem blight caused by on highbush blueberry () in Michigan.

The U.S. is the world's leading producer of highbush blueberries ( L.

A Rapid Glove-Based Inoculum Sampling Technique to Monitor in Commercial Vineyards.

Information on the presence and severity of grape powdery mildew (GPM), caused by , has long been used to guide management decisions. While recent advances in the available molecular diagnostic assays and particle samplers have made monitoring easier, there is still a need for more efficient field collection of . The use of vineyard worker gloves worn during canopy manipulation as a sampler (glove swab) of was compared with samples identified by visual assessment with subsequent molecular confirmation (leaf swabs) and airborne spore samples collected by rotating-arm impaction traps (impaction traps).

Development of a PNA-LNA-LAMP Assay to Detect an SNP Associated with QoI Resistance in .

The repetitive use of quinone outside inhibitor fungicides (QoIs, strobilurins; Fungicide Resistance Action Committee [FRAC] 11) to manage grape powdery mildew has led to development of resistance in . While several point mutations in the mitochondrial cytochrome gene are associated with resistance to QoI fungicides, the substitution of glycine to alanine at codon 143 (G143A) has been the only mutation observed in QoI-resistant field populations. Allele-specific detection methods such as digital droplet PCR and TaqMan probe-based assays can be used to detect the G143A mutation.

First report of halo blight on hop (Humulus lupulus) caused by Diaporthe humulicola in Minnesota.

Halo blight, caused by Diaporthe humulicola, is an emerging issue in hop production in the Upper Midwestern and Eastern North America. Reports of halo blight thus far have included Connecticut, Michigan, New York, and Quebec (Allan-Perkins et al.; Hatlen et al.

First report of Neofusicoccum ribis causing stem blight and dieback of blueberry (Vaccinium corymbosum) in Michigan.

In July 2020, a 3-year-old 'Envoy' northern highbush blueberry bush (Vaccinium corymbosum L.) from a commercial farm in Van Buren County, Michigan was submitted to the Plant & Pest Diagnostics laboratory at Michigan State University. Field disease assessments across the 2-acre planting were an incidence of 2-5% and a severity of 50-100%.

Optimizing Molecular Detection for the Hop Downy Mildew Pathogen in Plant Tissue.

Downy mildew-free hop plantlets and rhizomes are essential to limit the introduction of this destructive pathogen, , into hopyards. The objective of this research was to determine which DNA-based diagnostic tools are optimal for detection in plant tissue. Quantitative real-time PCR (qPCR) assays with TaqMan probes for nuclear () and mitochondrial () DNA loci were developed and tested side by side.

Rotting Grapes Don't Improve with Age: Cluster Rot Disease Complexes, Management, and Future Prospects.

Cluster rots can be devastating to grape production around the world. There are several late-season rots that can affect grape berries, including Botrytis bunch rot, sour rot, black rot, Phomopsis fruit rot, bitter rot, and ripe rot. Tight-clustered varieties such as 'Pinot gris', 'Pinot noir', and 'Vignoles' are particularly susceptible to cluster rots.

Identification of Putative SDHI Target Site Mutations in the SDHB, SDHC, and SDHD Subunits of the Grape Powdery Mildew Pathogen .

Succinate dehydrogenase inhibitors (SDHIs) are fungicides used in control of numerous fungal plant pathogens, including , the causal agent of grapevine powdery mildew (GPM). Here, the , , and genes of were screened for mutations that may be associated with SDHI resistance. GPM samples were collected from 2017 to 2020 from the U.

First report of halo blight of hop (Humulus lupulus) caused by Diaporthe humulicola in Quebec, Canada.

Halo blight of hop caused by Diaporthe humulicola has recently been reported in Michigan and Connecticut (Higgins et al. 2021, Allan-Perkins et al 2020). In August 2020 growers in Quebec, Canada reported necrotic foliar lesions and desiccation of the hop strobile (cone) on Chinook and Nugget cultivars.

Population Genetic Analyses of Isolates From Michigan Vineyards Using a High-Throughput Marker System Approach.

As sequencing costs continue to decrease, new tools are being developed for assessing pathogen diversity and population structure. Traditional marker types, such as microsatellites, are often more cost effective than single-nucleotide polymorphism (SNP) panels when working with small numbers of individuals, but may not allow for fine scale evaluation of low or moderate structure in populations. is a necrotrophic plant pathogen with high genetic variability that can infect more than 200 plant species worldwide.

The hop downy mildew pathogen Pseudoperonospora humuli.

Unlabelled: Pseudoperonospora humuli is an obligate biotrophic oomycete that causes downy mildew, one of the most devastating diseases of cultivated hop, Humulus lupulus. Downy mildew occurs in all production areas of the crop in the Northern Hemisphere and Argentina. The pathogen overwinters in hop crowns and roots, and causes considerable crop loss.

Allele-Specific Detection Methods for QoI Fungicide-Resistant in Vineyards.

Grapevine powdery mildew (GPM), caused by the fungus , is a constant threat to worldwide production of grape berries, requiring repeated use of fungicides for management. The frequent fungicide applications have resulted in resistance to commonly used quinone outside inhibitor (QoI) fungicides and the resistance is associated with single-nucleotide polymorphisms (SNPs) in the mitochondrial gene (). In this study, we attempted to detect the most common SNP causing a glycine to alanine substitution at amino acid position 143 (i.

Fungicide Efficacy Against and Point Mutations Linked to Carboxylic Acid Amide Resistance in Michigan.

Hops have expanded as a niche crop in Michigan and other production areas in the eastern United States, but growers in these regions face annual downy mildew outbreaks incited by , exacerbated by frequent rainfall and high relative humidity. We evaluated the efficacy of foliar- and drench-applied fungicides against downy mildew and examined Michigan isolates for point mutations linked to carboxylic acid amide (CAA) resistance. Disease severity and density were assessed weekly in 2016 and 2017 in nontrellised research hop yards in Michigan.

Etiology of Halo Blight in Michigan Hopyards.

Michigan's hop acreage ranks fourth nationally, but the state's growers contend with unique disease challenges resulting from frequent rainfall and high humidity. In August 2018, a Michigan hop grower reported necrosis and blighting of foliage and shattering of cones resulting in yield loss. Irregular-shaped lesions developed on leaves, surrounded by a halo of chlorotic tissue, and cone bracts became brown.

Validation of a Preformulated, Field Deployable, Recombinase Polymerase Amplification Assay for Species.

Recombinase polymerase amplification (RPA) assays are valuable molecular diagnostic tools that can detect and identify plant pathogens in the field without time-consuming DNA extractions. Historically, RPA assay reagents were commercially available as a lyophilized pellet in microfuge strip tubes, but have become available in liquid form more recently-both require the addition of primers and probes prior to use, which can be challenging to handle in a field setting. Lyophilization of primers and probes, along with RPA reagents, contained within a single tube limits the risk of contamination, eliminates the need for refrigeration, as the lyophilized reagents are stable at ambient temperatures, and simplifies field use of the assays.