Occurrence and Distribution of spp. in Fields Rotated with Sweetpotato and Host Range of a North Carolina Population of .

Root-knot nematodes (RKNs, spp.) are some of the most economically important and common plant parasitic nematodes in North Carolina (NC) cropping systems. Soil samples collected from fields planted with crops rotated with sweetpotato ( [L.

as a Potential Vector of , the Causal Agent of Sweetpotato Black Rot, in Storage Facilities.

, the causal agent of sweetpotato black rot, is a pathogen capable of developing and spreading within postharvest settings. A survey of North Carolina sweetpotato storage facilities was conducted to determine the arthropods present and identify potential vectors of . Sixteen taxonomic categories were recovered, and the genus (Diptera: Drosophilidae) accounted for 79% of individuals sampled, with being the most abundant species.

Effector Repertoire of the Sweetpotato Black Rot Fungal Pathogen .

In 2015, sweetpotato producers in the United States experienced one of the worst outbreaks of black rot recorded in history, with up to 60% losses reported in the field and packing houses and at shipping ports. Host resistance remains the ideal management tool to decrease crop losses. Lack of knowledge of biology represents a critical barrier for the deployment of resistance to black rot in sweetpotato.

, 100 Years Later: Research Mile Markers from 1922 to 2022.

In 1922, was described by Leon Hatching Leonian as a new pathogen infecting pepper (), with disease symptoms of root rot, stem and fruit blight, seed rot, and plant wilting and death. Extensive research has been conducted on over the last 100 years. This review succinctly describes the salient mile markers of research on with current perspectives on the pathogen's distribution, economic importance, epidemiology, genetics and genomics, fungicide resistance, host susceptibility, pathogenicity mechanisms, and management.

Clade-Specific Monitoring of Airborne spp. Sporangia Using Mitochondrial DNA Markers for Disease Management of Cucurbit Downy Mildew.

Management of cucurbit downy mildew (CDM) caused by , relies on an intensive fungicide program. In Michigan, CDM occurs annually due to an influx of airborne sporangia and timely alerts of airborne inoculum can assist growers in assessing the need to initiate fungicide sprays. This research aimed to improve the specific detection of airborne sporangia by adapting quantitative real-time polymerase chain reaction (qPCR) assays to distinguish among clades I and II and in spore trap samples from commercial production sites and research plots.

Populations Are Structured by Host, Geography, and Fluopicolide Sensitivity.

epidemics are propelled by warm temperatures and wet conditions. With temperatures and inland flooding in many locations worldwide expected to rise as a result of global climate change, understanding of population structure can help to inform management of in the field and prevent devastating epidemics. Thus, we investigated the effect of host crop, geographical origin, fungicide sensitivity, and mating type on shaping the population structure of in the eastern United States.

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.

A Comprehensive Characterization of Ecological and Epidemiological Factors Driving Perennation of Chasmothecia on Hop ().

Hop powdery mildew, caused by the ascomycete fungus , is a consistent threat to sustainable hop production. The pathogen utilizes two reproductive strategies for overwintering and perennation: (i) asexual vegetative hyphae on dormant buds that emerge the following season as infected shoots; and (ii) sexual ascocarps (chasmothecia), which are discharged during spring rain events. We demonstrate that chasmothecia, in the absence of any asexual growth forms, are a viable overwintering source capable of causing early season infection two to three orders of magnitude greater than that reported for perennation via asexual growth.

Fantastic Downy Mildew Pathogens and How to Find Them: Advances in Detection and Diagnostics.

Downy mildews affect important crops and cause severe losses in production worldwide. Accurate identification and monitoring of these plant pathogens, especially at early stages of the disease, is fundamental in achieving effective disease control. The rapid development of molecular methods for diagnosis has provided more specific, fast, reliable, sensitive, and portable alternatives for plant pathogen detection and quantification than traditional approaches.

A Multiplex TaqMan qPCR Assay for Detection and Quantification of Clade 1 and Clade 2 Isolates of and .

The ability to detect and quantify aerially dispersed plant pathogens is essential for developing effective disease control measures and epidemiological models that optimize the timing for control. There is an acute need for managing the downy mildew pathogens infecting cucurbits and hop incited by members of the genus ( clade 1 and 2 isolates and , respectively). A highly specific multiplex TaqMan quantitative polymerase chain reaction (PCR) assay targeting unique sequences in the pathogens' mitochondrial genomes was developed that enables detection of all three taxa in a single multiplexed amplification.

Effects of Water Temperature, Inoculum Concentration and Age, and Sanitizers on Infection of , Causal Agent of Black Rot in Sweetpotato.

Black rot, caused by , is a devastating postharvest disease of sweetpotato that recently re-emerged in 2014. Although the disease is known to develop in storage and during export to overseas markets, little is known as to how pathogen dispersal occurs. This study was designed to investigate dump tank water as a means of dispersal through four different types of water treatments: inoculum concentration (0, 5, 5 × 10, 5 × 10, and 5 × 10 spores/ml), inoculum age (0, 24, 48, 96, and 144 h), water temperature (10°C, 23°C, 35°C, and 45°C), and presence of a water sanitizer (DryTec, SaniDate, FruitGard, and Selectrocide).

The Effector Repertoire of the Hop Downy Mildew Pathogen .

is an obligate biotrophic oomycete that causes downy mildew (DM), one of the most destructive diseases of cultivated hop that can lead to 100% crop loss in susceptible cultivars. We used the published genome of to predict the secretome and effectorome and analyze the transcriptome variation among diverse isolates and during infection of hop leaves. Mining the predicted coding genes of the sequenced isolate OR502AA of .

Population Structure of from Greenhouse Floral Crops in Michigan.

causes seedling damping-off and root and crown rot in greenhouse ornamental plants. To understand the population dynamics and assess population structure of in Michigan floriculture crops, simple sequence repeats (SSRs) were developed using the previously published predicted transcriptome. A total of 166 isolates sampled from 2011 to 2013 from five, one, and three greenhouses in Kalamazoo, Kent, and Wayne Counties, respectively, were analyzed using six polymorphic and fluorescently labeled SSR markers.

Resurgence of cucurbit downy mildew in the United States: Insights from comparative genomic analysis of .

, the causal agent of cucurbit downy mildew (CDM), is known to exhibit host specialization. The virulence of different isolates of the pathogen can be classified into pathotypes based on their compatibility with a differential set composed of specific cucurbit host types. However, the genetic basis of host specialization within is not yet known.

Analysis of microsatellites from the transcriptome of downy mildew pathogens and their application for characterization of populations.

Downy mildew pathogens affect several economically important crops worldwide but, due to their obligate nature, few genetic resources are available for genomic and population analyses. Draft genomes for emergent downy mildew pathogens such as the oomycete , causal agent of cucurbit downy mildew, have been published and can be used to perform comparative genomic analysis and develop tools such as microsatellites to characterize pathogen population structure. We used bioinformatics to identify 2,738 microsatellites in the predicted transcriptome and evaluate them for transferability to the hop downy mildew pathogen, , since no draft genome is available for this species.

Characterization, Virulence, Epidemiology, and Management of Anthracnose in Celery.

Leaf curling and petiole twisting of celery (Apium graveolens) were observed in several commercial fields in five Michigan counties in 2010 through 2012, causing significant crop damage and loss. Prior to this time, the pathogen Colletotrichum acutatum species complex had not been previously associated with celery in Michigan. In this study, the pathogen's genotype and phenotype were characterized, the influence of environmental conditions determined, and fungicides tested.

Epidemiology and population biology of Pseudoperonospora cubensis: a model system for management of downy mildews.

The resurgence of cucurbit downy mildew has dramatically influenced production of cucurbits and disease management systems at multiple scales. Long-distance dispersal is a fundamental aspect of epidemic development that influences the timing and extent of outbreaks of cucurbit downy mildew. The dispersal potential of Pseudoperonospora cubensis appears to be limited primarily by sporangia production in source fields and availability of susceptible hosts and less by sporangia survival during transport.

Resurgence of Pseudoperonospora cubensis: The Causal Agent of Cucurbit Downy Mildew.

The downy mildew pathogen, Pseudoperonospora cubensis, which infects plant species in the family Cucurbitaceae, has undergone major changes during the last decade. Disease severity and epidemics are far more destructive than previously reported, and new genotypes, races, pathotypes, and mating types of the pathogen have been discovered in populations from around the globe as a result of the resurgence of the disease. Consequently, disease control through host plant resistance and fungicide applications has become more complex.

Genetic diversity, population structure, and resistance to Phytophthora capsici of a worldwide collection of eggplant germplasm.

Eggplant (Solanum melongena L.) is an important solanaceous crop with high phenotypic diversity and moderate genotypic diversity. Ninety-nine genotypes of eggplant germplasm (species (S.

The cucurbit downy mildew pathogen Pseudoperonospora cubensis.

Unlabelled: Pseudoperonospora cubensis[(Berkeley & M. A. Curtis) Rostovzev], the causal agent of cucurbit downy mildew, is responsible for devastating losses worldwide of cucumber, cantaloupe, pumpkin, watermelon and squash.

Distinct amino acids of the Phytophthora infestans effector AVR3a condition activation of R3a hypersensitivity and suppression of cell death.

The AVR3a protein of Phytophthora infestans is a polymorphic member of the RXLR class of cytoplasmic effectors with dual functions. AVR3a(KI) but not AVR3a(EM) activates innate immunity triggered by the potato resistance protein R3a and is a strong suppressor of the cell-death response induced by INF1 elicitin, a secreted P. infestans protein that has features of pathogen-associated molecular patterns.

Characterization of Phytophthora infestans populations in Colombia: first report of the A2 mating type.

Phytophthora infestans, the causal agent of late blight in crops of the Solanaceae family, is one of the most important plant pathogens in Colombia. Not only are Solanum lycopersicum, and S. tuberosum at risk, but also several other solanaceous hosts (Physalis peruviana, S.

Evidence for positive selection in putative virulence factors within the Paracoccidioides brasiliensis species complex.

Paracoccidioides brasiliensis is a dimorphic fungus that is the causative agent of paracoccidioidomycosis, the most important prevalent systemic mycosis in Latin America. Recently, the existence of three genetically isolated groups in P. brasiliensis was demonstrated, enabling comparative studies of molecular evolution among P.