Browsing by Author "Uchanski, Mark, committee member"
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Item Open Access A survey of the arthropod fauna associated with hemp (Cannabis sativa L.) grown in eastern Colorado(Colorado State University. Libraries, 2019) Schreiner, Melissa, author; Cranshaw, Whitney, advisor; Uchanski, Mark, committee member; Peairs, Frank, committee memberIndustrial hemp was found to support a diverse complex of arthropods in the surveys of hemp fields in eastern Colorado. Seventy-three families of arthropods were collected from hemp grown in eight counties in Colorado in 2016, 2017, and 2018. Other important groups found in collections were of the order Diptera, Coleoptera, and Hemiptera. The arthropods present in fields had a range of association with the crop and included herbivores, natural enemies, pollen feeders, and incidental species. Hemp cultivars grown for seed and fiber had higher insect species richness compared to hemp grown for cannabidiol (CBD). This observational field survey of hemp serves as the first checklist of arthropods associated with the crop in eastern Colorado. Emerging key pests of the crop that are described include: corn earworm (Helicoverpa zea (Boddie)), hemp russet mite (Aculops cannibicola (Farkas)), cannabis aphid (Phorodon cannabis (Passerini)), and Eurasian hemp borer (Grapholita delineana (Walker)). Local outbreaks of several species of grasshoppers were observed and produced significant crop injury, particularly twostriped grasshopper (Melanoplus bivittatus (Say)). Approximately half (46%) of the arthropods collected in sweep net samples during the three year sampling period were categorized as predators, natural enemies of arthropods. These findings are of significance considering the expanding cultivation of hemp both within the region of study and across the United States. A website developed to extend the information developed in this project has been accessed over 20,000 times in 28 months, indicating there is wide interest in this subject area.Item Open Access Assessing the market channel performance of Colorado fruit and vegetable producers(Colorado State University. Libraries, 2017) Christensen, Jeremiah Q., author; Thilmany, Dawn, advisor; Jablonski, Becca, advisor; Uchanski, Mark, committee memberThe growing popularity of locally sourced fruits and vegetables in the United States provides an opportunity for small and mid-sized farms to improve viability through sales to local markets. However, there is little research that looks at differences in business performance in these markets, and specifically, how labor allocation and marketing expenditures may vary by market. Based on the Market Channel Assessment Tool (MCAT) protocol developed in New York, variable costs (except those associated with production) and revenues were collected via market channel through farm interviews and labor logs recorded by producers during a one-week period spanning the peak marketing season in 2016 in Colorado. Following the New York model, it is expected that richer cost and revenue information can be used to support improved market decisions related to balancing market channel portfolios for individual farm participants. Moreover, aggregated data was used to establish performance benchmarks by market channel and region for producers to use for comparisons to peers. In addition, a two-dimensional fixed effect model quantified the impact of farm level attributes on market channel profitability. Results indicate channel profitability is positively impacted by the share of harvest labor involved in marketing and number of market channels, while negatively impacted by the share of labor facilitating sales (staffing market stands or making calls to buyers) and the number of crops grown. Extension agents and other agriculture support providers can use these results to support more involved farm market channel decision-making and efficient variable input expenditure recommendations.Item Open Access Chemical control of Cytospora leucostoma, a major limiting factor of peach production in western Colorado(Colorado State University. Libraries, 2017) Miller, Stephan, author; Stewart, Jane, advisor; Minas, Ioannis, advisor; Norton, Andrew, committee member; Uchanski, Mark, committee memberCytospora canker, Cytospora leucostoma, is a major limiting factor of peach production in Colorado, accounting for 15-20% of crop production loss annually. Given the unique environmental factors of the western slope region of Colorado, C. leucostoma has developed into a severe fungal disease, reducing yields annually. Chemical measures are important for Cytospora control as few options currently exist for preventing new infections. The specific objectives of the following thesis are to: (1) evaluate the efficacy of conventional and organic fungicides for C. leucostoma control, (2) test wound sealing fungicides, embedded in paint or kaolin clay, to develop preventive and containment approaches in existing orchards. Topsin, Topsin amended in 50% latex, Captan, Captan amended in 50% latex, 50% latex, lime sulfur, and lime sulfur amended in kaolin clay (Surround WP) showed evidence of efficacy from laboratory and field trials. Of these treatments, 50% latex, Topsin amended in 50% latex, and Captan amended in 50% latex, were shown to limit pathogen growth most effectively on pruning wounds during field trials in the summer season. In all field trials, however, NuCop showed absolutely no efficacy and should be avoided for C. leucostoma control in western Colorado. When various chemicals were tested on existing cankers to reduce spore inoculum loads, efficacy could not be statistically confirmed. The results of this study were compicated by variable field conditions and a large range of spore produced by each canker. Thus, larger sample sizes should be used in future studies to tease a part chemical efficacy and abiotic influences. Further, kaolin clay alone may shield fungal cankers from extreme temperatures, enhancing its growth in the field.Item Open Access Developing integrated pest management tactics for alfalfa mosaic virus and its aphid vector in chile peppers(Colorado State University. Libraries, 2023) Janecek, Taylor, author; Szczepaniec, Adrianna, advisor; Nachappa, Punya, committee member; Uchanski, Mark, committee memberAlfalfa mosaic virus (AMV, Bromoviridae: Alfamovirus) is a virus transmitted to plants by aphids in a non-persistent manner. The virus was first identified in chile peppers Capsicum annuum L. (Solanales: Solanaceae) in Southern Colorado in 2019. The goal of this research was to explore management strategies to suppress the virus given its devastating impact on the yield and quality of chile peppers. The objectives were to: 1) determine whether chile peppers have innate resistance to AMV, 2) test the effectiveness of host plant resistance and planting date modifications to suppress the virus in the field, 3) determine whether AMV is seed transmissible, and 4) survey abundance and diversity of aphids (Hemiptera: Aphididae) that likely transmit AMV in the system. In the greenhouse experiment, I found significant differences among varieties of chile peppers in the severity of AMV symptoms and identified a variety suitable for a field experiment. In the field, I found that the susceptible variety, Joe Parker, which tended to have high AMV symptoms in the greenhouse, was also highly susceptible to AMV in the field. Conversely, Mira Sol, which appeared to have resistance to the virus in the greenhouse screening assay had low incidence of AMV symptoms and low AMV titers in the field as well. Planting date also played an important role in symptom severity, where late planted peppers (mid-June) had significantly lower severity of AMV symptoms than peppers planted at conventional and early planting dates (the middle and end of May). Despite this, the yield and quality of peppers planted early was significantly greater than that of peppers planted later in the season. In addition, there was evidence of seed transmission of AMV in chile peppers, with 10% for Mira Sol and 2% for Joe Parker, from seeds collected from infected peppers had AMV. Lastly, I found high diversity of aphid species within my experimental plots (14-16 species) and lower diversity in nearby alfalfa fields (4-5 species). Moreover, severity and titers of AMV were positively correlated with earlier planting date, which was likely related to higher aphid densities early in the season. This research contributed to formulating integrated tactics that chile pepper producers can implement in their production to suppress the impact of AMV on the crop. Finally, this is the first report of AMV transmission through seed in peppers and is the first study describing this pathosystems in Colorado.Item Embargo Efficacy and impact of sanitizers in controlling pathogenic bacteria on irrigation water(Colorado State University. Libraries, 2024) Santillan Oleas, Valeria Paola, author; Gutierrez-Rodriguez, Eduardo, advisor; Geornaras, Gina, committee member; Uchanski, Mark, committee member; Ma, Jianbing, committee memberIrrigation water quality is crucial for fresh produce. However, the absence of practical microbial water standards and EPA-registered sanitizers poses challenges for growers, impacting food security and increasing the risk of foodborne outbreaks. This study compared the effectiveness of commercial sanitizers (sodium hypochlorite - Chlo, peroxyacetic acid - PAA) and novel chemistries (sodium acid sulfate - SAS, potassium acid sulfate - KAS) at different concentrations for achieving a 3-log reduction of E. coli O157:H7 (EHEC), Salmonella (SM), or Listeria monocytogenes (LM). Additionally, the study examined their corrosive effects on aluminum and stainless steel, as well as their impact on plant and soil chemical and physical properties. Sanitizer evaluations were conducted under varying turbidities (0, 50, 100, 150 NTU), contact times (CT: 3 or 5 minutes), and bacterial concentrations of EHEC, SM, or LM at 6 and 3 log CFU/mL per EPA 2020 guidelines. Treatments that achieved a 3-log reduction of the selected organisms within a 5-minute contact time, with no viable cells after enrichment, were considered the most effective and exceeded EPA requirements. These treatments were then evaluated for their corrosion capacity on stainless steel (SS304, SS316) and aluminum (AL3004) coupons, as well as their effects on soil and plant health (romaine lettuce) under greenhouse conditions. Chlo at 60 ppm, SAS at 0.60%, and PAA at 30 ppm achieved a 3-log reduction, with no viable cells after enrichment, for all strains after a 5-minute contact time (P<0.05). The corrosion capacity for the most effective treatments was tested at 14-day intervals at 23°C and 73°C for stainless steel (SS304, SS316) and aluminum (AL3004) coupons submerged in each sanitizer solution. There was no significant difference in corrosion between SS304 and SS316 (P<0.05). AL3004 showed greater corrosion than SS, with the highest rate observed at 0.6% SAS (4.52E-02 cm/year). Greenhouse-grown romaine lettuce was spray-inoculated with a bacterial cocktail of LM/EHEC at 5 log CFU/mL. Bacterial recovery was performed at 0-, 4-, 8-, and 12-days post-inoculation using selective-differential media. Soil samples were collected from treated and non-treated samples to assess soil chemical and physical properties. Bacterial inactivation had a negative correlation with water turbidity and a positive correlation with contact time and sanitizer concentration (P<0.05). In the greenhouse trial PAA, Chlorine and SAS exhibited a higher bacterial reduction compared to a water-control, with marginal differences in reduction between sanitizers (P<0.05). The highest reduction was achieved by PAA (0.98 log CFU/gram-lettuce) reduction compared to the water control. SAS exhibited phytotoxicity in the lettuce leaves in the second greenhouse trial. All sanitizers caused marginal changes in the overall properties of soil physical and chemical properties, with sodium and electrical conductivity being the main factors affected by the constant application of each sanitizer.Item Open Access Evaluating leafy green production in a Colorado rooftop agrivoltaic system(Colorado State University. Libraries, 2024) Villa-Ignacio, Armando, author; Bousselot, Jennifer, advisor; Uchanski, Mark, committee member; Sampath, Walajabad, committee memberCombining green roofs with solar modules can protect plants and produce energy in cities. Growing crops in this system is called rooftop agrivoltaics (RAV) and can complement current urban agriculture efforts. We evaluated a group of five leafy green crops (arugula, kale, lettuce, spinach, and Swiss chard) under different solar modules over two years at two locations. Data measurements were taken for fresh and dry weight (FW, DW) stomatal conductance (SC), plant size at harvest (PSH), and microclimate data. At the Colorado State University Foothills Campus, the treatments included a polycrystalline opaque silicon module, a cadmium telluride (CdTe) frameless opaque module, and a 40% semi-transparent CdTe module. At CSU Spur, there was an opaque module and a bifacial module. Both sites included a full sun control plot. At the Foothills campus, for of the five leafy greens produced higher FW and DW under the 40% semi-transparent modules compared to other treatments and the full sun control, except spinach. Most species also produced larger PSH under the PV module treatments compared to the full sun control. Leafy greens under the module treatments resulted in lower SC, however, lettuce and Swiss chard grown under the semi-transparent module treatment produced higher SC compared to all other treatments. At CSU Spur, plant responses were also species specific with arugula, kale, and lettuce yielding higher FW and DW in full sun. Most leafy greens resulted in lower SC, except for lettuce, which had a higher SC under solar module treatments. Spinach had no difference in FW but lower DW in the opaque treatment compared to the full sun control, and lower SC under both treatments. There was a lower FW between the bifacial treatment and the full sun control in Swiss chard. This research shows that incorporating photovoltaics on rooftop gardens influences the yield and stomatal conductance of select leafy green crops. While FW and DW mostly decreased under the deep shade treatments (opaque module, frameless module, and bifacial module) SC decreased, possibly due to less solar radiation on the leafy greens, reducing water use. Understanding the growth characteristics and growing environment of high value crops like leafy greens will increase understanding of what food crops are suitable for RAV systems.Item Open Access Evaluation of factors that contribute to the expansion and control of brassica insect pests in northern Colorado(Colorado State University. Libraries, 2018) Longtine, Zachary W., author; Cranshaw, Whitney, advisor; Kondratieff, Boris, committee member; Uchanski, Mark, committee memberHuman modifications to landscapes in agricultural areas can both eliminate and create new habitat for various organisms. One of the ways that sites are modified is by creating changes in plant communities. These can occur from physical disturbances from activities such as plowing or road building. Introduction and spread of non-native plants also greatly affects the types of plant communities common both within and outside of agricultural fields. The first part of this study consisted of an arthropod fauna survey on three non-native winter annual or perennial brassicaceous weeds that are presently common in disturbed sites in and around agricultural areas of Colorado: blue mustard, Chorispora tenella (L.), flixweed, Descurainia sophia (L.), and whitetop/hoary cress, Cardaria draba (L.). This survey was performed to see what insects, harmful and beneficial, might use them as bridge habitat between the winter and the growing season. Multiple locations where these plants are grown (typically in agricultural areas and disturbed sites) were chosen and were visited once a week during spring 2016 and 2017 and sampled with a sweep net. It was found that though flixweed supported the most genera, whitetop had the highest relative diversity in terms of both number of genera and evenness of numbers found. Blue mustard lacked in insect diversity. The most common phytophagous insects included false chinch bug (Nysius spp.), pale legume bug (Lygus elisus Van Duzee), diamondback moth, Plutella xylostella (L.) and western black flea beetle, Phyllotreta pusilla Horn. The most common natural enemy species present on the plants were parasitoid wasps and lady beetles though these and other beneficial insects were found in small numbers. It was concluded that these three brassicaceous weeds can might act as important ecological bridges for phytophagous insects. In part two of this study a test was conducted on the effects of supplemental insect food and wintergreen oil, which attract certain natural enemies, to reduce damage by certain lepidopteran pests associated with brassica crops. Plantings of broccoli, cabbage, and kale were sprayed weekly with the test treatments of supplemental insect food and supplemental insect food plus wintergreen oil. Weekly surveys of the plot were made to count numbers of imported cabbageworm, Pieris rapae (L.) and cabbage looper, Trichoplusia ni (Hübner) present and to note the presence of any natural enemy species. Harvest assessments were made of leaf injury to cabbage and the number of caterpillars present/head in broccoli. There were no significant statistical differences between treatments in regards to the number of insect pests present on plants or the injury produced.Item Open Access Farm food safety plans: customizing educational materials for small-scale and campus-based farms(Colorado State University. Libraries, 2017) Morris, Rachael E., author; Bunning, Marisa, advisor; Uchanski, Mark, committee member; Stone, Martha, committee member; Sullins, Martha, committee memberA comprehensive farm food safety plan is an integral part of all growing operations, regardless of size, output, or production practice. As small-scale and campus-based, student-run farms grow in popularity, there is an increasing need to establish the concept of comprehensive produce safety practices as a vital part of the farming process. Moreover, the passing of the Food Safety Modernization Act (FSMA) in 2011 addresses mandated accountability for large-scale agriculture within the Produce Safety Rule, but leaves many small farms exempt from regulation, including the types of farms targeted within this study. A need for a curriculum addressing produce safety on campus farms and small-scale operations, and lack of literature surrounding food safety training curriculum development drove the research design for this project. The components of this study were three fold: 1) university and college campus farm managers (n=12) from 14 states were surveyed on current practices; 2) classroom and on-farm presentations were developed and delivered to Colorado State University horticulture students (n=54), and a pre-and post- questionnaire was delivered to assess learning objectives; and 3) three on-line modules and a 27-page farm plan template were developed for Colorado growers, detailed during a webinar for Colorado Fruit and Vegetable Growers Association (CFVGA) members (participants n=33). Results offered positive a relationship between resource delivery and food safety knowledge for both students and growers. The pre-and post-questionnaire responses showed change (p≤0.05), including Likert scale questions stating that farm workers (p=0.001) and volunteers (p<0.0005) should receive food safety training. Post-webinar polling questions revealed that 100% (n=21) of voluntary respondents learned something new during the webinar, which focused on utilization of resources to build and modify farm food safety plans for any growing operation. With the national movement toward a prevention-focused food safety strategy, the need for implementing better produce safety practices has been identified as a top priority. Review and feedback from this study will aid in the continued development of materials for both campus and small-scale growers to expand their food safety practices.Item Open Access Management and epidemiology of Cytospora perennial canker, Cytospora plurivora, in western Colorado(Colorado State University. Libraries, 2021) Miller, Stephan T., author; Stewart, Jane, advisor; Ocheltree, Troy, committee member; Norton, Andrew, committee member; Minas, Ioannis, committee member; Uchanski, Mark, committee memberCytospora canker is a ubiquitous disease in deciduous fruit tree systems in western Colorado. The research conducted herein, explores the host-pathogen-environmental framework which has enabled Cytospora plurivora to thrive and become a threat to peach production in the region. My research also focuses on management strategies, both cultural and chemical, which can help mitigate pathogen infections. Chapter II, published in the Journal of Crop Protection, presents preventative control of C. plurivora through wound protection of pruned shoots. Several fungicides and sealants were evaluated either in vitro or in field trials, to explore antifungal activity. Fungicides which have been shown effective, were also evaluated for half maximum effective concentration rates (EC50) to better understand pathogen dose sensitivity. Chapter III explores the susceptibility of thirteen peach cultivars to C. plurivora infection under different abiotic conditions. Abiotic stressors such as water deficit and high-pH can be major limiting factors to tree fruit production and can increase tree susceptibility and pathogen severity. My research shows increased severity of C. plurivora infection and decreased plant water potentials when trees experienced increased soil pH and irrigation deficits. Chapter IV provides a detailed analysis of the epidemiology of C. plurivora in the field. This study estimates spore production rates and lesion infection rates over a 12-month period. Further, it evaluates possible dissemination mechanisms of C. plurivora, reporting detection of C. plurivora spores in aerial and on insect samples, although at low concentrations. The results presented herein help inform management strategies by elucidating field patterns of C. plurivora and identifying effective cultural and chemical control measures.Item Open Access Nitrogen mineralization from biofertlizer Azolla mexicana compared to traditional organic fertilizers(Colorado State University. Libraries, 2018) Jama, Aisha, author; Davis, Jessica G., advisor; Stromberger, Mary, committee member; Uchanski, Mark, committee memberOrganic agriculture has become an essential approach to meeting the growing global food production demand and long-term soil sustainability, as well as addressing environmental problems connected with the use of synthetic agrochemicals. As a result, biofertilizers (biological fertilizers) have become promising resources to meet the growing demands for healthy and safe food production. Biofertlizers supply nutrients and take advantage of microorganisms that contribute to sustainable practices. One such biofertilizer is the aquatic pteridophyte Azolla mexicana which can be found in both tropical and temperate climates. Azolla can multiply rapidly, ensuring year-round biomass, and has also been found to have fast and high rate of N fixation. Azolla strains have been successfully exploited as effective biofertilizers in Asia but strains native to the Great Plains have not. There is no literature that assesses N mineralization (Nmin) rates of Azolla mexicana compared to other organic fertilizers in Colorado soils. A laboratory soil incubation was conducted to determine the rates of Nmin, N availability and total C and N of Azolla mexicana applied to soils compared to commonly-used organic fertilizers. Then, a greenhouse study was conducted to assess the organic fertilizer and urea treatment responses on kale growth and yield, leaf and petiole N percentage, total N uptake and percentage N recovery. In this study, we hypothesized that Azolla biofertilizer application will enhance soil inorganic nitrogen (soil ammonium-N and nitrate-N) concentrations and that soil amended with Azolla will also enhance vegetable plant growth parameters (plant height, leaf and petiole N percentage, total N uptake and percentage N recovery). In the incubation study, soil NH4+-N for all treatments tended to increase until day 56 where they all peaked then subsequently decreased until the end of the incubation period. Compost treatment recorded higher initial soil NH4+-N while Azolla + Watanabe treatment recorded higher soil NH4+-N concentration towards the end of the study. The soil NO-3-N concentrations in all treatments increased throughout the 140-day study. The Azolla + Watanabe treatment showed highest average soil NO-3-N concentration at day 140 while the Control treatment had the lowest soil NO-3-N concentration throughout the experiment. The decline in soil NH4+-N concentration formed during ammonification was followed by an increase in soil NO-3-N concentration because of nitrification. In the greenhouse study, Azolla + Watanabe treatments had taller kale, significantly higher leaf fresh weight as well as significantly higher leaf dry weight. Both Azolla + Watanabe and Urea treatments recorded significantly higher yields compared to the other treatments. The Azolla + Watanabe and both Cyano treatments recorded significantly higher root dry weights compared other treatments. Control treatment had significantly higher root to shoot ratio. There were no significant differences in leaf N (%) among Azolla + Watanabe, Azolla, Cyano and Cyano + Moringa treatments. Azolla + Watanabe treatment also had significantly higher total N uptake among the organic fertilizers but was not significantly different from Azolla. Urea treatment recorded significantly higher N recovery and showed a similar pattern as the total N uptake whereby Azolla + Watanabe had significantly higher N recovery.Item Open Access Plant secondary metabolites enhance survival and pathogen tolerance in the European honey bee: a structure-function study(Colorado State University. Libraries, 2019) Hogeboom, Alison, author; Norton, Andrew, advisor; Bjostad, Louis, committee member; Uchanski, Mark, committee memberAdequate nutrition is essential for European honey bee (Apis mellifera) colony growth, and productivity, yet foraging limitations resulting from factors such as habitat loss often lead to dietary deficiencies. Plant secondary metabolites are key constituents of floral nectar that support physiological processes in honey bees, however, these compounds are only available to bees with access to a diversity of floral resources. Furthermore, the relationship between different classes of plant secondary metabolites and their function within honey bee diets requires further investigation. Using a structure-function framework, we evaluated whether four structurally similar plant secondary metabolites found in the nectar of common agricultural crops elicit comparable effects on honey bee survival and pathogen tolerance. The addition of plant secondary metabolites to artificial nectar solution enhanced median survival, in some cases more than doubling the lifespan of worker honey bees. Moreover, plant secondary metabolites demonstrated nutraceutical effects, and sometimes elicited medicinal effects on honey bees infected with Nosema ceranae. Our findings provide a platform to identify plant secondary metabolites which can augment current management techniques to support the long-term sustainability of the apiculture industry.Item Embargo Survival and persistence of Salmonella enterica in dry bulb onion production practices; a risk assessment approach(Colorado State University. Libraries, 2023) Carpenter, Griffin, author; Gutierrez-Rodriguez, Eduardo, advisor; Prenni, Jessica, advisor; Bunning, Marisa, committee member; Uchanski, Mark, committee memberThe first chapter of this research thesis focuses on onion production practices and the potential risks associated with contamination of dry bulb (DB) onions along the cropping cycle with human enteric pathogens. Dry bulb onions are a widely consumed vegetable globally that has been previously thought to be safe from human pathogen contamination. This literature review summarizes the history of outbreak-related information, the biology of etiologies of interest, the body of literature associated with microbial risks and onions, and pre-and post-harvest production practices with respect to the risk of contamination with human pathogens. The information discussed in this review is useful for portraying the complex interactions of the microorganisms of interest and for industry professionals, producers, and consumers with respect to management and applicable risk mitigation efforts in the future for DB onions. The second chapter of this research thesis focuses on determining the microbial risk factors associated with pre-and post-harvest commercial DB onion production practices. In the past 30 years DB onions have not been involved in foodborne illness outbreaks in the United States. However, two major multi-state foodborne outbreaks linked to Salmonella spp. (Sal) in 2020 and 2021 have altered the perception of producers and consumers about the microbial safety of this crop. Despite significant efforts to identify the source and route of contamination, little knowledge exists regarding the risk factors associated with enteric pathogen contamination along the DB onion cropping cycle. Thus, the goal of this research was to develop risk assessment profiles of DB onion production practices capable of identifying and reducing Sal contamination in pre-and post-harvest activities. DB onion cultivars grown in the state of Colorado were used to determine the ability of these onions to potentially inhibit Sal. This was achieved by testing the minimum inhibitory concentration (MIC) with a cocktail of attenuated and pathogenic Sal at 3,600 mg/L of onion slurry. All evaluations indicated that there was no significant inhibition of Sal irrespective of the type of strain or DB onion cultivar. Pre- and post-harvest risk quantification was determined based on field inoculations of a 2-strain attenuated Salmonella (attSal) cocktail. Survival and persistence of attSal was assessed at multiple production stages including at the 3 leaf stage, lifting, topping, curing, harvest, transport, and packing house environments. From these evaluations, results indicate that attSal is capable of surviving in both DB onions and soil for over a period of 64 days across the entire cropping cycle including harvest. Cultivar, agronomic practice, and UV index had no significant impact in our ability to recover attSal and in the survival of these strains along the cropping cycle in soil or DB onion. At harvest, the population of attSal on DB onion was 3.4 MPN/g at the three-leaf stage development (3LS), log 2.07 cfu/g at topping and log 1.87 cfu/g at lifting irrespective of DB onion cultivar. During interstate transport, the population of attSal further decreased to undetectable levels (< 3.0 MPN/g of DB onion). This scenario was considered a low-risk event for packinghouse purposes. Commercially grown DB onions were also included in all packinghouse evaluations. These onions were free from naturally occurring Sal and were inoculated with chalk containing attSal to mimic soil dust contamination. This chalk had an initial attSal population of log 5.5 cfu/g DB onion and for packinghouse purposes, it was considered a high-risk contamination event. A total of 14 locations within the packing line were selected to test the potential transfer of attSal from inoculated DB onions to control treatments and food contact surfaces. Additionally, DB onions from both high and low-risk contamination events were collected during sorting and packing. In both high and low -risk packing line contamination events, attSal was not recovered from any food contact surface or DB onions (Totl N= 897) over the course of 4 days of processing. A dry sanitation event was implemented in the packing line to assess whether such approaches could reduce contamination from attSal or any other residues left by the crop or by previous activities at the packing line. Our dry sanitation cleaning protocol involved the cleaning of the crop contact surface with a dry brush-single use paper towel, followed by sanitation with a food grade alcohol wipe, followed by a spray of an ethanol alcohol solution (food grade) at 75%, followed by a final removal of alcohol residues with a dry single-use paper towel. This approach proved to be effective in reducing packing line residues Adenosine triphosphate (ATP) measurements and the population of two indicator organisms Enterobacteriaceae (EB) and Escherichia coli (EC). However, the effectiveness varied with the type of surface. Plastic and camel hair bristles were not cleanable. There was no correlation between the population of EB and EC and the presence of attSal from high and low-risk contamination events. Dry sanitation events clearly indicated that it is a viable and useful practice that could be implemented on DB onion packing lines. The absence of cleaning and sanitation will be conducive to significant accumulation of DB onion debris and for the potential proliferation of indicator and pathogenic organisms. These findings are important to industry professionals, producers, and consumers regarding developing risk profiles and application of risk mitigation strategies to improve the microbial safety of DB onions.Item Open Access The role of chemical canopy sprays and irrigation methods on the incidence of the perennial canker, Cytospora plurivora in western Colorado peach orchards(Colorado State University. Libraries, 2022) Wright, Sean, author; Stewart, Jane E., advisor; Charkowski, Amy, committee member; Uchanski, Mark, committee memberCytospora plurivora is a secondary pathogen that has reached near epidemic levels in peach orchards on the western slope of Colorado. C. plurivora is responsible for Cytospora canker disease and is a limiting factor in peach production in the Grand Valley. Peach growers have limited management methods available to combat this disease, which prompted an investigation into irrigation practices as well as prophylactic chemical sprays following freeze events. In late 2020, the western slope received a freeze event that caused severe damage to peach shoots, buds, and twigs. Freeze damage provides infection courts within tree tissues that C. plurivora can infect. This freeze event prompted growers to apply prophylactic chemical sprays of Captan, lime sulfur, and lime sulfur with the addition of NuFilm. An efficacy threshold of three-months post chemical spray was determined for both Captan and lime sulfur treatments. Lime sulfur with the addition of NuFilm showed a loss of efficacy at two-months post spray. Additionally, an investigation into the movement of C. plurivora conidia under differing irrigation techniques was conducted. Both drip and micro-sprinkler treatments had positive detections for C. plurivora over the course of the study. In these studies, conidia traveled much greater distances than previously shown, traveling up to 135m from the closest canker. Understanding how chemical canopy sprays and different watering practices affect the incidence of Cytospora canker disease will assist in preserving the peach industry on the western slope of Colorado.Item Open Access Understanding the phytochemistry of high-CBD hemp: efficacy of common row cover materials for pollen exclusion and impact on flower phytochemistry(Colorado State University. Libraries, 2022) Bowen, Janina K., author; Prenni, Jessica, advisor; Cranshaw, Whitney, committee member; Uchanski, Mark, committee memberProduction of high-cannabidiol (high-CBD) hemp (Cannabis sativa L.) is steadily increasing in Colorado and across the United States. However, the impact of management practices on flower phytochemistry in this crop remains relatively unexplored. For example, there is high potential for male hemp plants from fiber and grain cultivars to pollinate exclusively female high-CBD hemp plants grown in close proximity, but it is unknown how the cannabinoid content of high-CBD hemp flowers is affected by pollination. We hypothesized that high seed content resulting from pollination will negatively impact the phytochemical yield of high-CBD crops. In this study, three experimental pollen exclusion treatments were applied to two cultivars of high-CBD hemp, 'Cherry Uno' and 'Wife.' Treatments included non-woven thick row cover (largest pore size of approximately 50 microns), non-woven thin row cover (largest pore size approximately 200 microns), woven insect netting (average pore size 700x240 microns), and uncovered controls. A total of 60 high-CBD plants (clones) were planted in a randomized complete block design at the Colorado State University Agricultural Research, Development and Education Center South (ARDEC South) in Fort Collins, Colorado (lat. 40.611804 N; long. -104.997144 W; elevation 1525 meters). Total biomass and seed weights for 60 whole plants were evaluated. Additionally, 5 cm inflorescence samples were taken from each plant, in concordance with the 2019 Colorado Department of Agriculture (CDA) sampling protocol. Seeds and floral material were weighed separately before samples were homogenized in preparation for cannabinoid analysis. Extracts were analyzed by ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) to determine the quantitative profiles of 20 cannabinoids. Results indicate that for the cultivar Cherry Uno, thick and thin row cover treatments effectively reduced pollination as compared to uncovered controls. The row cover treatments did not result in a statistically significant reduction of pollination for cultivar Wife, which may be due to later flowering in this cultivar. For cultivar Cherry Uno, a significant reduction in CBD concentration of up to 2.7% was observed in the heavily seeded controls compared to covered plants (Uncovered control = 3.77% CBD, 0.13% Δ9THC; Thin row cover = 6.49% CBD, 0.21% Δ9THC). Taken together, our results suggest that implementation of strategies to minimize pollination and/or remove seeds from high-CBD hemp biomass could improve cannabinoid yield. More research is warranted to evaluate the economic viability of such strategies and the effectiveness across different cultivars and growing climates.