Publications by authors named "Malvick D"

Bacterial leaf streak (BLS) of corn caused by pv. was first reported in the United States in 2017. The biology and management of BLS are poorly understood.

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Tar spot of corn ( L.) is a significant disease in the United States and Canada caused by , an obligate biotroph fungus. However, field research critical for understanding and managing the disease has been hindered by a need for methods to inoculate corn with in field environments.

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Sudden death syndrome (SDS), caused by , is an important yield-limiting disease of soybean (). From 1996 to 2022, cumulative yield losses attributed to SDS in North America totaled over 25 million metric tons, which was valued at over US $7.8 billion.

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Plant disease resistance genes are widely used in agriculture to reduce disease outbreaks and epidemics and ensure global food security. In soybean, Rps (Resistance to Phytophthora sojae) genes are used to manage Phytophthora sojae, a major oomycete pathogen that causes Phytophthora stem and root rot (PRR) worldwide. This study aims to identify temporal changes in P.

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Article Synopsis
  • Tar spot is an escalating disease affecting corn, caused by the fungus Phyllachora maydis, and has been found in 18 U.S. states and one Canadian province as of 2023.
  • A new method was developed to successfully infect 100% of corn plants with tar spot, using vacuum-collection tools to harvest spores and maintaining specific humidity and temperature conditions.
  • The findings allow for consistent disease study and highlight that storage conditions of spores can significantly influence the success of disease induction.
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  • Charcoal rot, primarily influenced by environmental stressors, negatively impacts soybean and dry bean yield and quality, with increasing concern due to global climate change.
  • A study sequenced the genomes of 95 isolates from soybean and dry bean across the U.S., Puerto Rico, and Colombia, revealing distinct genetic groupings, especially that U.S. isolates showed a clonal structure and significant genetic differentiation compared to those from Puerto Rico and Colombia.
  • Redundancy analysis showed that climate significantly impacts genomic variation, especially temperature seasonality and precipitation, identifying genes related to fungal stress responses that assist in adaptation to climatic changes.
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The genus contains numerous obligate fungal parasites that produce raised, melanized structures called stromata on their plant hosts referred to as tar spot. Members of this genus are known to infect many grass species but generally do not cause significant damage or defoliation, with the exception of . which has emerged as an important pathogen of maize throughout the Americas, but the origin of this pathogen remains unknown.

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Aims: To isolate and characterize fungi associated with diseased soybean seedlings in Midwestern soybean production fields and to determine the influence of environmental and edaphic factors on their incidence.

Methods And Results: Seedlings were collected from fields with seedling disease history in 2012 and 2013 for fungal isolation. Environmental and edaphic data associated with each field was collected.

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Article Synopsis
  • - Sudden death syndrome (SDS) in soybeans is caused by a fungus that first appeared in Arkansas in 1971 and has since spread throughout the Midwest, primarily affecting roots and leaves through toxins.
  • - Research shows that while the pathogen has limited genetic diversity in North America, it exhibits varying levels of virulence, indicating different isolates can impact plants differently.
  • - Three distinct genetic population clusters of the fungus were identified across the Midwest, with different clusters showing varying levels of genetic diversity and virulence, highlighting their roles in the disease's spread.
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causes root and stem diseases on soybean and sugar beet, and fungicides are commonly used to manage these diseases. Quinone outside inhibitor (QoI) fungicides (pyraclostrobin and azoxystrobin) have been used for in-furrow and postemergence application since 2000. Succinate dehydrogenase inhibitor (SDHI) fungicides (sedaxane, penthiopyrad, and fluxapyroxad) became popular seed treatments after their registration in Minnesota and North Dakota between 2012 and 2016.

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Random-effect meta-analyses were performed on data from 240 field trials conducted between 2005 and 2018 across nine U.S. states and Ontario, Canada, to quantify the yield response of soybean after application of foliar fungicides at beginning pod (R3) stage.

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Tar spot of corn has been a major foliar disease in several Latin American countries since 1904. In 2015, tar spot was first documented in the United States and has led to significant yield losses of approximately 4.5 million t.

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is the causal agent of Goss's leaf blight and wilt, an important disease of maize in the United States and Canada. The epidemiology and ecology of this bacterial pathogen are poorly understood. Infested maize residue is often considered to be the primary source of inoculum for maize; however, the potential for many other plant species to be infected and serve as inoculum sources is unknown.

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As complete host resistance in soybean has not been achieved, Sclerotinia stem rot (SSR) caused by continues to be of major economic concern for farmers. Thus, chemical control remains a prevalent disease management strategy. Pesticide evaluations were conducted in Illinois, Iowa, Michigan, Minnesota, New Jersey, and Wisconsin from 2009 to 2016, for a total of 25 site-years ( = 2,057 plot-level data points).

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A meta-analytic approach was used to summarize data on the effects of fluopyram-amended seed treatment on sudden death syndrome (SDS) and yield of soybean (Glycine max L.) in over 200 field trials conducted in 12 U.S.

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Sclerotinia sclerotiorum causes Sclerotinia stem rot (SSR) (also called white mold), resulting in stem rot and death of many common herbaceous ornamental plant species. Resistant plants would be useful to manage SSR; however, the host range of S. sclerotiorum is unclear.

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Sudden death syndrome (SDS) of soybean, caused by Fusarium virguliforme, is a significant disease of soybean. The suite of factors that influence disease development is incompletely understood. The goal of this study was to determine the effects of pathogen population levels, crop residues, seed exudates, and their interactions on development of SDS and growth of F.

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Pythium spp. cause seed decay, damping-off, and root rot in soybean and corn; however, their diversity and importance as pathogens in Minnesota are unknown. Our objectives were to identify the Pythium spp.

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Oomycete pathogens are commonly associated with soybean root rot and have been estimated to reduce soybean yields in the United States by 1.5 million tons on an annual basis. Limited information exists regarding the frequency and diversity of oomycete species across the major soybean-producing regions in North America.

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Goss's leaf blight and wilt of maize (corn) is a significant and reemerging disease caused by the bacterium Clavibacter michiganensis subsp. nebraskensis. Despite its importance, molecular tools for diagnosing and studying this disease remain limited.

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The ability to accurately detect and quantify Fusarium virguliforme, the cause of sudden death syndrome (SDS) in soybean, in samples such as plant root tissue and soil is extremely valuable for accurate disease diagnoses and to address research questions. Numerous quantitative real-time polymerase chain reaction (qPCR) assays have been developed for this pathogen but their sensitivity and specificity for F. virguliforme have not been compared.

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Existing crop monitoring programs determine the incidence and distribution of plant diseases and pathogens and assess the damage caused within a crop production region. These programs have traditionally used observed or predicted disease and pathogen data and environmental information to prescribe management practices that minimize crop loss. Monitoring programs are especially important for crops with broad geographic distribution or for diseases that can cause rapid and great economic losses.

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Background: Sudden death syndrome (SDS) of soybean caused by Fusarium virguliforme spreads and reduces soybean yields through the North Central region of the U.S. The fungal pathogen and Heterodera glycines are difficult to manage.

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Growth and anatomical responses of plants during latent and pathogenic infection by fungal pathogens are not well understood. The interactions between soybean (Glycine max) and two types of the pathogen Phialophora gregata were investigated to determine how plants respond during latent and pathogenic infection. Stems of soybean cultivars with different or no genes for resistance to infection by P.

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