Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Evaluation of wheat production practices under wheat streak mosaic disease risk and wheat stem sawfly pressure in Montana(Montana State University - Bozeman, College of Agriculture, 2020) McKelvy, Uta; Chairperson, Graduate Committee: Mary Burrows; Monica Brelsford, Jamie Sherman and Mary Burrows were co-authors of the article, 'Susceptibility and tolerance of winter wheat, spring wheat and barley cultivars to mechanical inoculation with wheat streak mosaic virus' submitted to the journal 'Plant health progress' which is contained within this dissertation.; Peggy Lamb, Monica Brelsford and Mary Burrows were co-authors of the article, 'Impact of planting date, seeding rate and cultivar choice on spring and winter wheat productivity and profitability in Montana' submitted to the journal 'Agronomy journal' which is contained within this dissertation.; David Weaver and Mary Burrows were co-authors of the article, 'Evaluation of chemical and cultural management practices for wheat stem sawfly control and effects on beneficial insects in spring wheat in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this dissertation.Wheat (Triticum aestivum L.) is an economically important crop for Montana's agricultural industry. Wheat streak mosaic (WSM) is an important viral disease in Montana and the wheat stem sawfly (WSS; Cephus cinctus Norton) is a major insect pest in the state. Understanding these disease and pest problems and the factors that promote and suppress disease and pest pressure forms the foundation for a successful integrated pest management program. In this dissertation, we evaluate wheat production practices in Montana and provide information on the effectiveness and implications of cultural and chemical management practices in mitigating WSM disease and WSS pressure. We assessed the tolerance of popular winter wheat, spring wheat, and barley cultivars in Montana to mechanical inoculation with WSMV in field studies. Winter wheat 'Brawl CL Plus' and breeding lines CO12D922 and MTV1681 demonstrated moderate WSMV incidence and minor yield penalties under WSMV inoculation, making them suitable cultivars to be grown in high-risk environments. We investigated the effects of cultivar choice, planting date, and seeding rate on grain yield and quality parameters in field studies. Our results validated current planting date recommendations for Montana. Yield reductions were observed at planting dates later than mid-September and April for winter wheat and spring wheat, respectively. No yield increase was observed when winter wheat was planted before mid-September. No meaningful and reliable economic benefits were associated with an increase in seeding rate beyond the recommended density. We developed a WSM risk prediction model and released it as the online learning tool AWaRe ('Assessment of Wheat streak mosaic Risk'). AWaRe presents the first learning tool that integrates complex information on the dynamics underlying WSM disease and relates them to the user in an interactive way. We expect the adoption of risk assessment based WSM management practices that result in a reduced economic impact through the use of this tool. The potential of different insecticides to manage WSS damage was compared to spring wheat genotypes with varying degrees of WSS resistance. Results showed that application of the systemic insecticide Thimet-20G provided effective protection of susceptible cultivar 'Reeder,' but use of solid-stem cultivars were similarly effective.Item Chemical control and disease reservoir studies of the wheat curl mite (Aceria tosichella Keifer), vector to wheat streak mosaic virus(Montana State University - Bozeman, College of Agriculture, 2016) Murphy, Carmen Yvette; Chairperson, Graduate Committee: Mary BurrowsWheat streak mosaic virus (WSMV) causes yield loss to wheat (Triticum aestivum) in all areas of the world where the crop is grown. No chemical controls for the WSMV vector, the wheat curl mite (WCM, Aceria tosichella Keifer), are approved. Control relies primarily on avoiding a 'green-bridge' of living plant material that can host the disease between seasons. This study aimed to 1) identify chemical treatments for WCM control under conventional and organic systems and clarify misconceptions that treatments, such as sulfur, control WCM and 2) analyze the capacity of 20 grassy species to serve as reservoirs of WSMV and WCM. The effects of insecticides with varying modes of action (carbamate, organophosphate, pyrethroid, neonicotinoid, biological control, oil, ovicide, mite growth inhibitor, and soap) on WCM population growth were tested in the greenhouse. Treatment with the active ingredients aldicarb and chlorpyrifos decreased WCM populations compared to untreated controls (p<0.001 and p<0.001). Field trials were conducted in spring wheat in 2013 and winter wheat in 2013-2014. Similar effects on WSMV spread were not observed in field trials. These trials included ten products consisting of five modes of action: organophosphates, pyrethroid, oil, soap and mite growth inhibitor. Chlorpyrifos was included in the field trials, but no efficacy was seen in 2013 compared to controls under good infection and incidence and infection was low in 2014, therefore we were unable to distinguish any treatment effect. To assess the capacity of 20 grassy species to serve as reservoirs of WSMV and WCM, plants with varying lifespan and origin were grown in the greenhouse and infested with viruliferous WCM. Lifespan had the greatest impact on ability of plants to host WCM (p=0.011) and WSMV (p<0.001). Annual plant species are more likely to host WCM than perennial grasses, with all species hosting WCM. Native and introduced species tested did not differ in ability to host WCM (p=0.735) and WSMV (p=0.096). This study provides evidence of potential for use of active ingredient chlorpyrifos in WCM control, and showed that lifespan is an important determinant of WSMV disease reservoir potential of grassy species.Item Purification and serology of barley yellow streak mosaic virus(Montana State University - Bozeman, College of Agriculture, 1993) Skaf, Jihad S.Item Epidemiology of wheat curl mite (Aceria tosichella K.) and wheat streak mosaic virus on feral grass species and effect of glyphosate on wheat curl mite dispersal(Montana State University - Bozeman, College of Agriculture, 1998) Brey, Christopher WilliamItem Factors influencing the outcome of barley yellow streak mosaic virus-Petrobia latens-barley interactions(Montana State University - Bozeman, College of Agriculture, 1995) Smidansky, Eric DanielItem Chemotherapeutic elimination of genetic components(Montana State University - Bozeman, College of Agriculture, 1983) Miller, Roger VincentItem Symptomatology and transmissibility of the mosaic disease of great northern bean(Montana State University - Bozeman, College of Agriculture, 1933) Norris, Bernice HelenItem Evaluation of susceptibility to wheat streak mosaic virus among small grains and alternative hosts in the Great Plains(Montana State University - Bozeman, College of Agriculture, 2011) Ito, Dai; Chairperson, Graduate Committee: Mary Burrows.Wheat streak mosaic virus (WSMV), endemic in small grains production areas of the Great Plains, causes yield losses of wheat 2 to 5% annually. Yield loss in individual fields can reach 100%. Control relies on cultural practices to control the vector, the wheat curl mite (Aceria tosichella Keifer, WCM), and the use of resistant or tolerant varieties. WSMV and WCM depend on living tissue for survival and reproduction, including common grassy weeds. Little is known about the relative importance of these weeds as alternative hosts of WSMV. The purpose of these studies was to evaluate the risk of infection with WSMV in commonly grown wheat varieties and various grassy weed species, information useful to understanding WSMV epidemiology and control. Winter wheat, spring wheat and barley varieties in Montana were evaluated in the field by measuring the effect of fall vs. spring inoculation and variety on incidence, symptom severity, and yield components. Winter wheat varieties from five states, and spring wheat and barley varieties from Montana were tested for incidence and absorbance in greenhouse. Fall-inoculated winter wheat had less effect of WSMV inoculation compared to spring-inoculated winter wheat. Yields of spring wheat varieties were largely reduced by WSMV inoculation. There was no correlation between yield and incidence or symptom severity. In greenhouse studies, the highest incidence was observed in varieties from Idaho and Nebraska, whereas the highest relative absorbance was observed in varieties from Montana. In 2008 and 2009, surveys of common grassy weeds were conducted. Grass species from croplands in six states were selected and mechanically inoculated to determine the susceptibility to WSMV. Grassy weeds were also evaluated as a source of WSMV by measuring transmission efficiency with virulifeous WCM. Bromus tectorum was the most prevalent grassy weed and the most frequent viral host. Aegilops cylindrica, and Avena fatua had the highest incidence and relative absorbance. There were no differences in the susceptibility of grass species to WSMV by their state of origin. WCM transmission study indicated infected grass species had lower transmission efficiency than from infected wheat. These studies will benefit producers in Montana to assess their risk of WSMV based on variety selection and the presence of grassy weeds.