Neil Gudmestad - NDSU Publications

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    Augmenting Fungicidal Activity of Tetraconazole with Chemosensitization Agents for Cercospora Leaf Spot Management
    (North Dakota State University, 2017) Metz, Nicholas James
    Cercospora beticola (Sacc.) is the causal agent of Cercospora leaf spot (CLS). CLS is considered to be one of the most destructive foliar diseases of sugar beet in the world. CLS is managed in part through resistant cultivars, crop rotation, and cultural practices, but timely fungicide applications are necessary to manage disease effectively. Heavy reliance on fungicides to manage CLS has led to the development of resistance to multiple classes of fungicides. The most widely used class of fungicides is the demethylation inhibitors (DMIs). DMI-resistant C. beticola isolates have been increasing in incidence over the past decade. Chemosensitization agents (CAs) are compounds that have little to no antifungal activity, but may increase efficacy of commercial fungicides when co-applied. CAs could lead to better management of CLS and reduced production costs.
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    Biology and Management of Fusarium Species on Sugar Beet
    (North Dakota State University, 2017) Lai, Xiao
    Minnesota and North Dakota together produce about 51% of the beet sugar in the United States of America. Fusarium diseases caused by Fusarium oxysporum f. sp. betae and F. secorum on sugar beet cause significant reduction in both root yield and sucrose concentration. This research was conducted to determine the best inoculation methods to induce Fusarium diseases on sugar beet seeds and plants and to evaluate fungicides for their efficacy at controlling Fusarium diseases in greenhouse conditions. The use of Fusarium colonized barley seeds in close proximity to sugar beet seeds and seedlings caused similar level of disease severity as the standard root-dipping method, and reduced the time for evaluation by directly inoculating seeds and 4-leaf stage plants rather than using older plants which have to be transplanted into new pots. Pydiflumetofen and metconazole fungicides used in-furrow have the potential to provide effective control of Fusarium diseases on sugar beet.
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    Characterization of Cytochrome B from European Field Isolates of Cercospora Beticola with Quinone Outside Inhibitor Resistance
    (North Dakota State University, 2012) Birla, Keshav
    Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is the most important foliar disease of sugar beet worldwide. Control strategies for CLS rely heavily on fungicides including quinone outside inhibitor (QOI) fungicides. We collected 866 C. beticola isolates from sugar beet growing regions in France and Italy and assessed their sensitivity to the QOI fungicide pyraclostrobin. To gain an understanding of the molecular basis of QOI resistance, we cloned the full-length coding region of Cbcytb. All tested QOI-resistant isolates harbored a point mutation in Cbcytb at nucleotide position 428 that conferred an exchange from glycine to alanine at amino acid position 143 (G143A). A PCR assay was developed to discriminate QOI-sensitive and QOI-resistant isolates based on the G143A mutation. Our results indicate that QOI resistance has developed in some European C. beticola populations in Italy and monitoring the G143A mutation is an essential fungicide resistance management strategy.
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    Characterization of Sensitivity of Sclerotinia Sclerotiorum Isolates from North Central U.S. to Thiophanate-Methyl and Metconazole
    (North Dakota State University, 2013) Ameen, Gazala
    Sclerotinia sclerotiorum (Lib.) de Bary causes Sclerotinia stem rot on canola and many other crops of economic importance in the U.S. SSR is primarily controlled with fungicides applied at flowering time. Most fungicides currently used to control SSR can promote resistance buildup in their target populations making monitoring of sensitivity important. In this study the reaction of S. sclerotiorum to thiophanate-methyl (TM) and metconazole (MTZ) was characterized. Samples collected in several states of north central U.S. were used. Three and ten isolates were considered to be moderately insensitive to TM and MTZ, respectively. Greenhouse trials indicated, however, that diseases caused by these isolates could be effectively controlled using currently recommended doses of each compound. In vitro sensitivity to TM was temperature dependent. A previously unreported mutation at codon E111D in the β-tubulin gene of a TM-moderately insensitive isolate was identified.
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    Downy Mildew of Sunflowers: Establishment of Baseline Sensitivity to Azoxystrobin and Monitoring for the Development of Fungicide Resistance and Plasmopara Halstedii Virulence Phenotype Changes
    (North Dakota State University, 2017) Gilley, Michelle A.
    Downy mildew, caused by Plasmopara halstedii (Farl.) Berl. and de Toni, is an economically important disease in cultivated sunflowers, Helianthus annuus L. The objectives of this study were to determine disease pressure in North Dakota and South Dakota, determine the virulence phenotypes in the pathogen population, determine the baseline sensitivity to azoxystrobin and evaluate select isolates for fungicide insensitivity. While downy mildew was present in many fields, incidence was typically low. To determine virulence phenotypes, selected isolates were evaluated on an expanded set of differential lines. New virulence was found to the Pl8 resistance gene, but no virulence was observed on the PlArg, Pl15, Pl17 and Pl18 genes. Using a discriminatory dose of 10 ug ai azoxystrobin/seed, no isolate approached infection levels found in inoculated, nontreated controls; therefore, the pathogen is considered sensitive to azoxystrobin in the greenhouse and azoxystrobin should still suppress downy mildew in the field.
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    Glycoalkaloid Profiling of Potato Genotypes from the North Dakota State University Potato Breeding Program
    (North Dakota State University, 2013) Roman Martinez, Irene
    Gylcoalkaloids (GA) are plant secondary metabolites that offer pests and disease resistance. Studies show correlation between GA content and CPB resistance. In this study, CPB resistance was assessed in a field trial at Grand Forks, ND, during 2012 for twenty-four genotypes from the NDSU Potato Breeding Program. Two treatments were applied, a block treated with imidacloprid (Admire®), and an untreated block. The treated block showed decreased CPB damage. Presence of aglycons (non-sugar moiety of GAs) was assessed by gas chromatography in foliar and tuber tissue. Distribution of GAs in the tuber was assessed to determine variation in tuber sections and whole tuber. Potato genotypes should be developed with tuber GAs levels below 20 mg/100 g fresh weight (FW) to ensure safety for human consumption. Focus should be on GAs that are only synthesized in the tuber, which will provide pests and disease resistance, while maintaining adequate yields and decreased inputs.
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    Marker Assisted Selection Increases the Efficiency of Breeding for Potato Virus Y Resistance in Potato
    (North Dakota State University, 2014) Harchenko, Whitney Ann
    Potato Virus Y (PVY) is an important virus of potato due to the non-persistent mode of transmission by aphids causing yield losses. Genetic resistance is the recommended control since insecticides cannot adequately control the spread of PVY by aphids. The gene Ryadg from S. tuberosum ssp. andigena provides resistance to all strains of PVY. This gene has genetically been mapped to chromosome XI, and linked polymerase chain reaction (PCR) based DNA markers have been identified. This study identified PVY resistant progeny by the use of the molecular sequence-characterized amplified region (SCAR) marker RYSC3. The RYSC3 marker allowed a simple and fast approach to determine if the Ryadg gene was present in the seedling family populations evaluated. The RYSC3 marker identified 16 families with progeny segregating for the Ryadg gene. Progeny segregated 1:1 for PVY resistance, fitting the model simplex (Ryryryry) for the Ryadg allele.
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    Plant-Parasitic Nematodes in Field Pea and Potato and their Effect on Plant Growth and Yield
    (North Dakota State University, 2018) Upadhaya, Arjun
    In this study, surveys were conducted in pea and potato fields in North Dakota and Central Minnesota to investigate the incidence and abundance of plant-parasitic nematodes in these fields. Moreover, the effect of the pin nematode, Paratylenchus nanus, on plant growth and yield of six field pea cultivars was determined under greenhouse conditions. Similarly, the influence of lesion nematode, Pratylenchus penetrans, and wilt fungi, Fusarium oxysporum alone and together on growth and yield of potato cultivar ‘Red Norland’, was evaluated in microplots under field conditions. The results indicate Paratylenchus spp. and Pratylenchus spp. are the most frequent nematodes, respectively, in pea and potato fields. Pin nematodes reproduced on field pea cultivars and caused up to 37% reduction in plant height and 40% reduction in yield. Additionally, both P. penetrans and F. oxysporum alone, and together had significant negative effect on growth and yield of potato.
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    Rhizoctonia Solani Damping-Off of Sugarbeet: Effect of Plant Growth Stage on Disease Severity and Management Using Penthiopyrad
    (North Dakota State University, 2015) Liu, Yangxi
    Rhizoctonia solani is the most damaging pathogen on sugarbeet (Beta vulgaris L.) in North Dakota and Minnesota. Research was conducted to evaluate penthiopyrad for controlling R. solani and determine when the plants are most susceptible to infection. Penthiopyrad applied in-furrow and as a soil drench resulted in significantly higher percent survival than the positive control whereas penthiopyrad applied in a band was ineffective at controlling R. solani. Penthiopyrad can also be used as a seed treatment at the 14 g rate to provide effective control of R. solani. Sugarbeet plants, irrespective of their inherent level of resistance, were easily infected by R. solani up to three weeks after planting, even longer for susceptible varieties, highlighting the need for additional protection in the form of seed treatment or fungicide application that may be required to protect vulnerable sugar beet planted in fields with a history of the disease.
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    Sensitivity of Sclerotinia Sclerotiorum Isolates From North Central US to Azoxystrobin and Boscalid
    (North Dakota State University, 2016) Munoz, Claudia Lucia
    Azoxystrobin and boscalid are fungicides frequently used to manage diseases caused by Sclerotinia sclerotiorum (Lib.) de Bary in many broadleaf crops in North Central US. . Continued use of these compounds can induce development of fungicide-resistant strains and thus their sensitivity should be monitored periodically. The objective of this research was to generate baseline sensitivity information of S. sclerotiorum to azoxystrobin and boscalid. Salicylhydroxamic acid was toxic to ascospores even at concentrations of 0.1 μg/ml and therefore was not used to estimate sensitivity to azoxystrobin. Azoxystrobin EC50 for ascospores and mycelium were 3.05 and 1.01 μg/ml, respectively. Boscalid EC50 for ascospores and mycelium were 8.38 and 0.11 μg/ml, respectively. S. sclerotiorum isolates collected before 2004 had statistically (P > 0.05) similar sensitivity to azoxystrobin but where more sensitive to boscalid (P =0.05) than isolates collected in 2014. Both fungicides continue to be effective tools to manage S. sclerotiorum.
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    Stochastic Budgeting and Input Breakeven Analysis in North Dakota Potato Production
    (North Dakota State University, 2017) Bingham, Alan
    Enterprise budgets were developed for non-irrigated red and irrigated russet potato production, based on North Dakota model farms. Costs and revenues vary among producers, thus budgets are intended to serve as a template for producers to use and manipulate to suit their individual circumstances. These budgets and stochastic (Monte Carlo) simulation were utilized in order to analyze and quantify financial risk in each respective enterprise. Simulated net returns for non-irrigated production ranged from -$1,324 to $2,757 per acre, while irrigated returns were between -$551 and $1,616 per acre. On farms where fumigation is a typical practice, it is one of the largest expenses to the enterprise. A break-even analysis was conducted based on market price and possible increases in yield and yield quality. The breakeven curve is downward sloping, as market price increases. Ideal product selection, based on assumed benefits, may vary depending on expected market price.