Identification of spp. on corn in North America and baseline flutriafol fungicide sensitivity.

Gray leaf spot (GLS) is an important corn disease reportedly caused by Cercospora zeae-maydis and C. zeina. Recently, flutriafol, a demethylation inhibitor (azole) fungicide received EPA registration as Xyway® LFR®, a product that is applied at planting for management of fungal diseases in corn, including suppression of GLS.

Foliar Inoculation of into Corn Induces Infection and Local Spread in Field Environments.

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.

Management of Soybean Cyst Nematode and Sudden Death Syndrome with Nematode-Protectant Seed Treatments Across Multiple Environments in Soybean.

As soybean () production continues to expand in the United States and Canada, so do pathogens and pests that directly threaten soybean yield potential and economic returns for farmers. One such pathogen is the soybean cyst nematode (SCN; ). SCN has traditionally been managed using SCN-resistant cultivars and rotation with nonhost crops, but the interaction of SCN with sudden death syndrome (SDS; caused by ) in the field makes management more difficult.

Plant Variety, Mycorrhization, and Herbivory Influence Induced Volatile Emissions and Plant Growth Characteristics in Tomato.

Plants produce a range of volatile organic compounds (VOCs) that mediate vital ecological interactions between herbivorous insects, their natural enemies, plants, and soil dwelling organisms including arbuscular mycorrhizal fungi (AMF). The composition, quantity, and quality of the emitted VOCs can vary and is influenced by numerous factors such as plant species, variety (cultivar), plant developmental stage, root colonization by soil microbes, as well as the insect developmental stage, and level of specialization of the attacking herbivore. Understanding factors shaping VOC emissions is important and can be leveraged to enhance plant health and pest resistance.

Effect of Fluopyram on on Corn in the Field and In Vitro.

The effects of a fluopyram seed treatment on lesion nematodes ( spp.) and other plant-parasitic nematodes (PPNs) were evaluated on corn in multiple field locations in 2020 and 2021. The highest rate of fluopyram seed treatment (0.

Is Associated with Necrotic Lesions in the Tar Spot Disease Complex? A Culture-Based Survey of Maize in Mexico and the Midwestern United States.

Tar spot, caused by , is an emerging disease of corn in the United States. Stromata of  are sometimes surrounded by necrotic lesions known as fisheyes and were previously reported to be caused by the fungus  . The association of  with fisheye lesions has not been well documented outside of initial descriptions from the early 1980s.

Efficacy and Profitability of Fungicides for Managing Frogeye Leaf Spot on Soybean in the United States: A 10-Year Quantitative Summary.

Frogeye leaf spot (FLS), caused by , is an economically important disease of soybean in the United States. Data from 66 uniform fungicide trials (UFTs) conducted from 2012 to 2021 across eight states (Alabama, Arkansas, Illinois, Iowa, Kentucky, Louisiana, Mississippi, and Tennessee) were gathered and analyzed to determine the efficacy and profitability of the following fungicides applied at the beginning pod developmental stage (R3): azoxystrobin + difenoconazole (AZOX + DIFE), difenoconazole + pydiflumetofen (DIFE + PYDI), pyraclostrobin (PYRA), pyraclostrobin + fluxapyroxad + propiconazole (PYRA + FLUX + PROP), tetraconazole (TTRA), thiophanate-methyl (TMET), thiophanate-methyl + tebuconazole (TMET + TEBU), and trifloxystrobin + prothioconazole (TFLX + PROT). A network meta-analytic model was fitted to the log of the means of FLS severity data and to the nontransformed mean yield for each treatment, including the nontreated.

Assessment of symptom induction via artificial inoculation of the obligate biotrophic fungus Phyllachora maydis (Maubl.) on corn leaves.

Objective: Tar spot is a foliar disease of corn caused by Phyllachora maydis, which produces signs in the form of stromata that bear conidia and ascospores. Phyllachora maydis cannot be cultured in media; therefore, the inoculum source for studying tar spot comprises leaves with stromata collected from naturally infected plants. Currently, there is no effective protocol to induce infection under controlled conditions.

Meta-Analytic Modeling of the Severity-Yield Relationships in Soybean Frogeye Leaf Spot Epidemics.

Frogeye leaf spot (FLS), caused by , is an important foliar disease affecting soybean in the United States. A meta-analytic approach including 39 fungicide trials conducted from 2012 to 2021 across eight states (Alabama, Arkansas, Illinois, Iowa, Kentucky, Louisiana, Mississippi, Tennessee) was used to assess the relationship between FLS severity and soybean yield. Correlation and regression analyses were performed separately to determine Fisher's transformation of correlation coefficients (Z), intercept (β) and slope (β).

First report of Curvularia leaf spot on Zea mays caused by Curvularia lunata in North Carolina.

In late July of 2022, corn leaves with spots were observed in a field at North Carolina State University's Vernon James Research and Extension Center (35.873294º N, 76.658599º W; Plymouth NC).

Virulence, Aggressiveness, and Fungicide Sensitivity of spp. Associated with Soybean in Illinois.

Phytophthora root and stem rot (PRR), caused by , is one of the most devastating oomycete diseases of soybean in Illinois. Single resistant genes () are used to manage this pathogen but has adapted to , causing failure of resistance in many regions. In addition to , recent reports indicate that could also cause root rot in soybean.

Field and Greenhouse Assessment of Seed Treatment Fungicides for Management of Sudden Death Syndrome and Yield Response of Soybean.

Seed treatments for the management of sudden death syndrome (SDS) caused by are available in the United States and Canada; however, side-by-side comparisons of these seed treatments are lacking. Sixteen field experiments were established in Illinois, Indiana, Iowa, Michigan, and Wisconsin, United States, and Ontario, Canada, in 2019 and 2020 to evaluate seed treatment combinations. Treatments included a nontreated check (NTC), fungicide and insecticide base seed treatments (base), fluopyram, base + fluopyram, base + saponin extracts from , base + fluopyram + heat-killed , base + pydiflumetofen, base + thiabendazole + heat-killed , and base + thiabendazole + extracts heat-killed .

Detection and discovery of plant viruses in soybean by metagenomic sequencing.

Background: Viruses negatively impact soybean production by causing diseases that affect yield and seed quality. Newly emerging or re-emerging viruses can also threaten soybean production because current control measures may not be effective against them. Furthermore, detection and characterization of new plant viruses requires major efforts when no sequence or antibody-based resources are available.

species infecting maize and other grass species in the Americas represents a complex of closely related species.

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.

Assessment of Selected Commercially Available Seed Treatments on Suppressing the Effects of Red Crown Rot on Soybeans Under a Controlled Environment.

is a soilborne fungus responsible for red crown rot (RCR) in soybeans. Recently, this disease has been detected in new areas within the United States and Asia, where it has been reported to cause significant yield losses. To date, no data on the efficacy of fungicide seed treatments for suppressing RCR in soybeans are available.

Contour-Based Detection and Quantification of Tar Spot Stromata Using Red-Green-Blue (RGB) Imagery.

Quantifying symptoms of tar spot of corn has been conducted through visual-based estimations of the proportion of leaf area covered by the pathogenic structures generated by (stromata). However, this traditional approach is costly in terms of time and labor, as well as prone to human subjectivity. An objective and accurate method, which is also time and labor-efficient, is of an urgent need for tar spot surveillance and high-throughput disease phenotyping.

Meta-Analysis of Soybean Yield Response to Foliar Fungicides Evaluated from 2005 to 2018 in the United States and Canada.

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.

Diaporthe Seed Decay of Soybean [ (L.) Merr.] Is Endemic in the United States, But New Fungi Are Involved.

Diaporthe seed decay can compromise seed quality in soybean [ (L.) Merr.] in the warm and humid production areas of the United States during crop maturation.

Occurrence of Quinone Outside Inhibitor Resistance in Virginia Populations of Infecting Wheat.

Stagonospora nodorum blotch (SNB) of wheat, caused by , is managed using cultural practices, resistant varieties, and foliar fungicides. Frequent fungicide use can select for fungicide resistance, making certain chemistries less effective; this may in part explain the increasing severity of SNB in the mid-Atlantic United States. Quinone outside inhibitor (QoI) resistance has been documented for a diversity of fungi, but it has not been reported for in the United States.

Assessing the Curative and Protective Impacts of Select Fungicides for Control of Powdery Mildew of Wheat.

Powdery mildew, caused by the obligate fungal pathogen , has been increasing in incidence and severity on wheat in the Chesapeake Bay region of the mid-Atlantic United States. Although fungicides are used for in-season management of powdery mildew, no studies to date have assessed the ability of these products to control disease after pathogen arrival/infection (curative activity) and the duration of disease control provided after fungicide application (protective activity) under controlled conditions. Five commercially available fungicide products, including Caramba, Stratego YLD, Priaxor, Prosaro, and Trivapro, were applied at either 3 or 5 days after inoculation with spores to assess curative activity.

Relationship Between Invasive Brown Marmorated Stink Bug () and Fumonisin Contamination of Field Corn in the Mid-Atlantic U.S.

Brown marmorated stink bug ( Stål) is an invasive agricultural pest that causes severe damage to many crops. To determine potential associations between feeding damage, infection, and mycotoxin contamination in field corn, a field survey was conducted in eight counties in Virginia. Results indicated an association between feeding damage and fumonisin contamination.

Meta-Analytic and Economic Approaches for Evaluation of Pesticide Impact on Sclerotinia Stem Rot Control and Soybean Yield in the North Central United States.

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).

Evaluating the Profitability of Foliar Fungicide Programs in Mid-Atlantic Soft-Red Winter Wheat Production.

In mid-Atlantic soft-red winter wheat (SRWW) production, the standard timing for a fungicide application is between flag leaf emergence (Feekes growth stage [FGS] 8) and heading (FGS 10.5). However, two-pass and anthesis (FGS 10.