College of Agriculture & Natural Resources
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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Managing Cover Crops for Better N Efficiency and Soil Health(2024) Stefun, Melissa; Weil, Ray; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Winter cover cropping is a major tool that agriculture can use to protect soil and water quality and mitigate climate change. Unlike farmland in the world at large, most Maryland cropland has seen little tillage disturbance and some level of cover cropping for decades. With that background, field experiments on two soils with contrasting textures at the Beltsville Facility of Central Maryland Research and Education Center tested the effects of cover crop management enhancements on nitrogen (N) leaching, soil health indicators, and cover crop N uptake over three years. Two cover crops (sole rye and a mixture of forage radish, crimson clover, and rye) were compared to a control where cover cropping was ceased. The cash crops were corn and soybean grown in rotation. With best nutrient management practices applied, suction lysimeter sampling at 90 cm depth from October through April showed low levels of N leaching in general, but NO3-N concentrations were significantly lower under cover crops. Overall mean concentrations of NO3-N were 2.20 mg N/L in the control but 0.43 mg N/L under cover crops. Additionally, soil water samples were digested to determine dissolved organic N (DON) which was found to make up between 44-60% of the total dissolved N in the leaching water. In additional experiments, a small fertilizer N application was made to cover crops to stimulate rapid deep rooting with the goal of accessing soluble N deep in the profile to increase N capture by more than the amount of N applied. The response to fall N fertilization failed to accomplish this goal and was not related to the surface soil NO3-N concentration as expected. In spring, cover crops were terminated on three dates from mid-April to mid-May and rye biomass doubled with each extra two weeks it was allowed to grow whether it was in the mix or alone. The effect of cover crops on soil health indicators was evident with increased soil permanganate oxidizable carbon, total soil carbon, lower bulk density, and greater aggregation. These experiments demonstrated that cover crops with enhanced management can have marked effects on an agricultural system already using sustainable practices.Item DESIGNING AN ACCESSIBLE AGRICULTURAL GARDEN: CONNECTING SOLIDARITY & AGROECOLOGY(2024) Boyle, Patrick Robert; Ruggeri, Deni; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis explores the potential of agroecology as a transformative framework for guiding the transition of Bergamo's agricultural landscape toward sustainability, resilience, and community well-being. Grounded in the evolution of agroecology from farm-scale design to regional planning, the research investigates how this approach can integrate ecological methodologies and participatory action research in design to implement sustainable farming practices, rehabilitate landscapes, and cultivate solidarity-driven producer-consumer relationships. By emphasizing the interconnectedness of ecology, economy, and society, the study addresses whether agroecology can shape a district into a resilient landscape that enhances people's lives and promotes health and well-being.Through an interdisciplinary lens, the thesis also delves into the broader concept of landscape, highlighting its role in social well-being and advocating for the protection and responsible management of landscapes as a fundamental human right. It explores the principles of landscape democracy and solidarity, aiming to empower communities to reconnect with their environments and promote ecological restoration through collective action and ethical practices. Ultimately, the research strives to contribute to the discourse on agroecology and landscape planning, offering proposals and strategies for actionable change in regenerative and organic agricultural systems that prioritize the needs and values of local communities.Item MAKING APPLES BLUSH: UNDERSTANDING HOW THE COMBINED USE OF REFLECTIVE GROUNDCOVERS AND PLANT GROWTH REGULATORS IMPACT RED SKIN COLORATION AND QUALITY OF ‘HONEYCRISP’ APPLES IN THE MID-ATLANTIC US(2024) Miah, Md Shipon; Farcuh, Macarena; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Apples are among the most valuable fruits globally, with 'Honeycrisp' ranking as the top sales-producing cultivar in the US. However, challenges such as insufficient red skin coloration and increased preharvest fruit drop significantly diminish their market value. Reflective groundcovers have been reported to enhance apple skin coloration, while the application of the plant growth regulator AVG reduces fruit drop but may negatively impact skin coloration. Research on the impacts of these practices in mid-Atlantic US-grown apples remains limited. In this two years study, our aims were 1) to evaluate the effect of reflective groundcovers on solar radiation (PPFD, UV) distribution; 2) to assess the combined effect of reflective groundcovers and ethylene inhibitor (AVG) on preharvest fruit drop, ethylene production, red blush percentage, and overall fruit quality; 3) to investigate the combined effect of reflective groundcovers and ethylene inhibitor (AVG) on expression level of key anthocyanin and ethylene biosynthesis related genes; 4) to determine the combined effect of reflective groundcovers and ethylene inhibitors (AVG) in the accumulation of total anthocyanin. Apples underwent four treatment combinations of reflective groundcover (Extenday) and AVG (130 mg L−1). Our findings revealed that Extenday significantly enhanced skin coloration (>75% blush) through increased reflectance of PPFD and UV radiation, along with increased IEC, while also accelerating fruit maturity, i.e., overripening. In fact, Extenday-only treated fruit exhibited the highest upregulation of ethylene and anthocyanin biosynthetic-related genes, as well as total anthocyanins. Conversely, AVG notably reduced fruit drop and decreased IEC, delaying fruit maturity while significantly diminishing red coloration (30–48% blush). AVG treated fruit significantly suppressed the expression of key ethylene and anthocyanin biosynthetic structural and regulatory genes, as well as total anthocyanins. The combined application of Extenday and AVG synergistically decreased fruit drop while enhancing skin coloration (>50% blush), but without inducing overripening. This combination fine-tuned the transcript accumulation of ethylene and anthocyanin biosynthetic-related genes, as well as total anthocyanins, enabling 'Honeycrisp' fruit to exceed 50% blush, while moderately increasing IEC (compared to Extenday-only and control fruit), thus enhancing fruit economic value. Therefore, combining Extenday and AVG can boost the market value for 'Honeycrisp' apples in the mid-Atlantic US.Item PRODUCTION RECOMMENDATIONS FOR INDUSTRIAL HEMP (CANNABIS SATIVA) FOR FIBER PRODUCTION IN MARYLAND: OPTIMIZING PLANTING DATE FOR FIBER YIELD, QUALITY, AND WEED MANAGEMENT(2024) Myers, Erin; Fiorellino, Nicole; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Management recommendations, namely timing of planting and harvest, are well established for a wide range of agronomic crops, but this data is lacking for industrial fiber hemp (Cannabis sativa L.), especially in the Mid-Atlantic region. With the re-introduction of legal hemp production in the US in 2014, farmers faced many challenges to growing this crop, both policy and production challenges alike. As hemp production was illegal since World War II, there was virtually no applied agronomic research performed on hemp in that time. Moreover, there are no pre-emergence herbicides approved for weed management in industrial hemp production, and research is needed to determine which cultural practices can be utilized to manage weeds in this crop. This void of applied research performed on fiber hemp has left many Land-Grant universities and Extension personnel unable to provide basic production recommendations to farmers interested in growing this novel crop. To begin providing such recommendations to Maryland farmers interested in incorporating fiber hemp into their crop rotation, the objectives of this research were to 1) determine the effect of planting and harvest date on fiber hemp yield, plant characteristics, and fiber quality and 2) observe weed populations under a competition or germination prevention scenario in fiber hemp across the planting date spectrum. Based on this research, we believe fiber hemp can be successfully incorporated into Maryland crop rotations, as early planting and harvest of fiber hemp will result in quality fiber hemp, management of weeds through available cultural practices, and minimal disruption to other agronomic crops.Item Dual water quality responses after more than 30 years of agricultural management practices in the rural headwaters of the Choptank River basin in the Chesapeake Bay watershed(2023) Silaphone, Keota; Fisher, Thomas R; Natural Resource Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Eutrophication is the water quality response to over-enrichment by nitrogen (N) and phosphorus (P) in fresh, estuarine, and coastal waters globally. Agricultural best management practices (BMPs) are the primary tool for controlling eutrophication in rural areas, particularly in the Chesapeake Bay watershed, where BMPs are vital to achieving TMDL goals. However, despite the application of BMPs, local water quality in the headwaters of the Choptank River, a major tributary of the Chesapeake Bay on the Delmarva Peninsula, has not improved. Thus, further investigation of agricultural BMP impacts on water quality in the Greensboro watershed is needed. My overarching research question is, “Why have N and P concentrations increased at the USGS Greensboro gauge if agricultural Best Management Practices (BMPs) have been implemented?” I applied statistical approaches to three linked, testable hypotheses to systematically evaluate agricultural BMPs and their impacts on nutrient (N and P) export from the Greensboro watershed. My first hypothesis was that agricultural BMPs have increased significantly in the Greensboro watershed. To test this hypothesis, I obtained publicly available modeling data via the Chesapeake Assessment Scenario Tool (CAST) and estimated the subsequent edge-of-stream N and P export. My findings indicated that the number of BMPs in the agricultural sector increased significantly between 1985 and 2021, supporting the hypothesis. Overall, modeled agricultural N and P export significantly decreased between 2010 and 2021 (p < 0.001). However, the modeled edge-of-stream agricultural nutrient export resulted in no significant change in N export and an increase of 3% in agricultural P export resulting from BMP implementation levels in 2021 compared to 2010. This study demonstrated the use of CAST to acquire reported BMP implementation levels and increased nutrient inputs into the Greensboro watershed between 1985 and 2021. The watershed nutrient inputs mirror the upward trends in N and P export captured by the USGS long-term monitoring station at Greensboro. With this improved access to BMP implementation and nutrient data, decision-makers can consider adaptive management measures to decrease nutrient export downstream. My second hypothesis was that agricultural BMPs have an adequate basis for estimating their capacity to reduce N export. To test this hypothesis, I conducted a meta-analysis on 689 cover crop N efficiencies reported in 18 empirical and modeling studies. The cover crop N efficiency was calculated as the ratio of an N interception by cover crop biomass or a reduction in soil or groundwater N divided by an N input, e.g., previous spring fertilizer or a previous soil or groundwater N concentration or flux. These variable approaches resulted in wide ranges in mean cover crop N efficiency (10-80%) due to empirical and modeling experimental approaches, varying methods, and parameters used to calculate efficiency. The modeling approach generally resulted in N efficiency values significantly higher than the empirical approach, as did the parallel control-treatment experiments compared to the sequential before-and-after implementation method. Because of these variables, there appears to be no standard methodology to report the effects of cover crops or standardized metadata describing the variables used in the N efficiency calculations. I suggest a standard methodology and metadata that should accompany future reports of cover crop N efficiencies to improve the modeled effects of BMPs on nutrient export. My third hypothesis was that three methods of estimating N and P concentrations and yields are in agreement and show a relationship to BMP implementation in the Greensboro watershed. To test this hypothesis, I compiled annual nutrient (N and P) datasets based on (1) USGS field measurements of concentrations and discharge, (2) USGS flow-normalized weighted regression based on time, discharge, and season (WRTDS) of concentrations and yields, and (3) CAST-modeled nutrient yields. Statistical analyses revealed time, discharge, agricultural BMPs, and animal waste management practice trends of the three methods. Results indicated that the USGS field measurements and WRTDS flow-normalization methods consistently showed an increase in N and P concentrations and yields. In contrast, all CAST-modeled regressions showed significantly decreasing nutrient concentrations and yields (p ≤ 0.05), which did not support the hypothesis that all three methods are in agreement. Despite CAST-modeled results decreasing with increasing BMPs, which supports the hypothesis that N and P concentrations and yields show a relationship with BMP implementation, USGS methods resulted in increasing nutrient concentrations and trends. These results indicated significant underestimates of modeled N and P export by CAST. I recommend using adjusted BMP efficiencies during cultural and structural BMP lifespans to improve model outputs. I also suggest two approaches to reflect the role of annual poultry manure applications: (1) model nutrient transport via artificial drainage ditches that interfere with natural nutrient flow pathways and exacerbate N and P transport, and (2) model the accumulation of soil-P and saturated soil-P, resulting in increases in dissolved P and particulate P in downstream surface waters. Agronomic recommendations include developing efficient manure recycling approaches within the local agricultural systems via nutrient management practices and concurrent research and development to support alternative uses of animal waste, including composting, bioenergy generation, granulating/pelletizing, and establishing a marketplace to support the sale of these products and to offset the costs of transporting manure from areas of manure surplus to manure deficit areas. This dissertation revealed that modeling studies overestimate cover crop N efficiencies in the United States Coastal Plain province and that CAST modeling is not in agreement with the USGS field measurements. CAST-modeled nutrient concentrations and yields decrease over time, indicating improvements in water quality. In contrast, USGS methods consistently show that nutrient concentrations and yields increase, indicating that BMPs are insufficient, inadequate, overwhelmed by nutrient inputs, or efficiencies are overestimated. Indeed, nutrient-reducing BMPs have increased between 1985 and 2021. With over 35 years of BMP implementation, measurable water quality response is expected. However, BMPs that relocate and apply higher amounts of manure annually have also increased with nutrient-reducing BMPs. Rising manure application rates combined with higher fertilizer application rates due to economic pressures on farmers to increase crop yields appeared to have overwhelmed implemented BMPs. Continued manure applications onto croplands in the Greensboro watershed suggest nutrient export will continue to rise; thus, reaching water quality goals is unlikely.Item DEVELOPMENT OF HORDEIN-PECTIN NANOPARTICLE COMPLEX FOR THE ENCAPSULATION OF BIOACTIVE COMPOUNDS FOR ENHANCED FUNCTIONALITIES(2023) Tarwa, Kevin; Wang, Qin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Nanoparticle delivery systems composed of food polymers are a sustainable and eco-friendly approach to protect functional ingredients and promote healthier food options. In this research, a hordein-pectin nanoparticle complex (HP-NPC) was fabricated using an anti-solvent precipitation and electrostatic deposition (pH 4) method for the encapsulation of hydrophobic bioactive compounds to enhance their functionalities. First, hordein was extracted from whole barley grains to obtain a dried powder to synthesize hordein nanoparticles (HNP). Then pectin with a degree of esterification (DE) around 71% was applied as a coating material. The average particle size of the freshly prepared nanoparticle complex was relatively small (~246 ± 11 nm), and Fourier transform infrared spectroscopy (FTIR) indicated that cationic hordein interacted with anionic pectin mainly though newly formed hydrogen bonds and electrostatic interaction as indicated by their opposite surface charges. Scanning electron microscopy (SEM) revealed that the morphology of the nanoparticle complex was spherical with a smooth surface. The pectin coating was shown to have a protective effect against pH (3.0-9.0), heat (80 °C for 0-120 mins), and salt (0-100 µM) which are all factors known to degrade proteins. Second, lutein, a hydrophobic bioactive xanthophyll was encapsulated into HP-NPC to develop a lutein-hordein/pectin nanoparticle complex (L-HP-NPC). Since lutein has low water solubility and low bioavailability in the gastrointestinal tract (GIT), the effect of the encapsulation system on the functional properties of lutein was investigated. The loading capacity (LC%) and encapsulation efficiency (EE%) was around 15.5 and 82%, respectively. In vitro digestion resulted in a higher bioaccessibility of lutein for encapsulated HP-NPC (~22.3%), which is defined as the percentage of lutein accessible for absorption in the simulated intestinal fluid (SIF) compared to lutein encapsulated into HNP (~9%). The ability of pectin to produce gels in acidic media was shown to have a significant effect against gastric enzymes that can degrade both hordein and lutein. Also, lyophilization (an important step in food processing) had no significant effect on the stability of L-HP-NPC. This encapsulation system could potentially be used as a functional ingredient in the food industry to develop healthy and nutritious foods for consumers. Third, carvacrol, a phenolic monoterpene known for its antimicrobial properties was encapsulated into HP-NPC to develop a carvacrol-hordein/pectin nanoparticle complex (CA-HP-NPC). Special focus was on the solubility of encapsulate carvacrol due to its known low solubility in aqueous solutions. The antimicrobial effectiveness of the encapsulated nanoparticle complex was tested against non-pathogenic gram-positive L. innocua and gram-negative E. coli K12. CA-HP-NPC was still able to maintain a relatively small particle size (~207 ± 8 nm) after being dispersed into water post-lyophilization. Carvacrol was shown to be effective against the two bacteria, however, CA-HP-NPC did not show antimicrobial effectiveness. Although carvacrol was successfully encapsulated into the nanoparticle complex, further studies on their release properties need to be investigated to further understand their functional properties for food applications.Item Utilizing algal turf scrubbers for bioremediation and bioenergy production(2023) Delp, Danielle Marie; Lansing, Stephanie A; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation researched the conversion of algal biomass that was generated as a byproduct of bioremediation by algal turf scrubbers (ATS) into bioenergy via anaerobic digestion. Anaerobic digestion is a bacterial process that converts organic material into bioenergy in the form of biogas that contains methane (CH4), the primary component of natural gas. Bioenergy yield was quantified as the volume of CH4 generated from digestion of the algae in relation to seasonal changes in algal biomass yield, different digester operational parameters, co-digestion of the biomass with more conventional digestion feedstock, and flocculation pre-treatment for dewatering of algae prior to digestion. The first study used a pilot-scale mesophilic digester at the Port of Baltimore (Baltimore, MD, USA) to continuously digest algae from a 122 m2 ATS on the Patapsco River over two years. Biomass generation was significantly correlated to maximum daily air temperature, water temperature, and flow rate in Year 1 but only water flow rate in Year 2. Algae of the taxa Ochrophyta dominated the algal turf, especially the filamentous diatom Melosira sp., in both years. In Year 1 of the study, two anaerobic digestion systems with variable hydraulic retention times (HRT), designated D1 (average HRT 45.0 ± 5.8 days) and D2-D3 (average HRT 61.0 ± 8.1 days) were used to digest the algae. The D1 generated 1090 L CH4 from 2416 L of algae over a 39-day HRT (59.1 ± 8.9 L algae/kg VS), and D2-D3 generated 1170 L CH4 from 2337 L of algae over a 53-day HRT (67.9 ± 11.0 L algae/kg VS). The difference in CH4 yield with two different HRTs was not significant. In Year 2, only the D2-D3 was operated and was modified to test the use of active recirculation and heating to improve digestion efficiency and CH4 yield. The D2-D3 system generated 4000 L of CH4 (163 ± 42 L algae/kg VS) from 3310 L of algae in Year 2. The second study consisted of laboratory-scale biomethane potential tests to test changes in CH4 yield when algae harvested from an Anacostia River (Bladensburg, MD, USA) ATS was co-digested with three wastes (dairy manure, food waste, and poultry litter) at algae:waste loading ratios of at 1:1, 1:2, 1:5, and 1:10 by organic material, or volatile solids (VS), content. The algal biomass was the least efficient substrate at generating CH4 when normalized by both mass VS digested (109 ± 4 mL CH4/g VS) and total mass of substrate digested (0.687 ± 0.025 mL CH4/g substrate). Co-digestion with all three of the wastes at all ratios tested significantly increased CH4 generation efficiency per mass VS compared to only digesting algae. However, the high moisture content of the algae (95.2%) relative to the other co-digestion wastes (29.0-84.6%) significantly decreased CH4 production on a mass basis for the dairy manure, food waste, and poultry litter when algae was added at any loading ratio. A lettuce growth experiment using the effluent of the digestion vessels showed no signs of acute toxicity when any of the diluted (8-fold) digester effluents were applied as fertilizer to the developing plants. The third and final study consisted of flocculation experiments that tested 500-mL of algae using four experimental treatments (FeCl3, electrocoagulation, chitosan, and Bacillus sp. RP 1137) to dewater algae harvested from the Anacostia River ATS and compared to gravity settling as a control. The experimental flocculants successfully increased the total solids (TS) of the ATS algae by 14-291% depending on the treatment, with electrocoagulation being the least effective and bacterial flocculation being the most effective flocculant. All treatments reduced total suspended solids (TSS) in the drained supernatant by >98%. The raw ATS algae and dewatered solids from the settling experiment were then digested for 35-days, with the algae yielding 49.6 ± 3.6 mL of CH4/g VS. The dewatered solids had reduced digestion efficiency by 29.6-71.0% compared to untreated algae. Dewatering pre-treatment increased CH4 yield from the algae when normalized by total g substrate fed to the reactor (1.65 ± 0.12 mL CH4/g substrate) for all treatments except bacteria 1x, however the effect was only significant for solids dewatered with electrocoagulation. The results from the three studies show that temperature drives algal growth patterns in temperate climates, which results in seasonally variable biomass yield from ATS, with a corresponding variability in CH4 production due to inconsistent availability of the algal feedstock. Algae can be co-digested with agricultural and food wastes that are generated year-round to reduce variability in feedstock availability. Thickening and dewatering the algae improves CH4 yield on a mass basis, however the digestion efficiency was reduced. In conclusion, the findings suggest that anaerobic digestion is a viable means of managing the algae harvested from ATS systems with and without co-digestion of the algal biomass.Item MANAGEMENT OPTIONS FOR FARMERS FACING SALTWATER INTRUSION ON THE EASTERN SHORE OF THE CHESAPEAKE BAY(2023) Schulenburg, Alison Nicole; Tully, Kate; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Rising sea levels, storms, and perigean spring tides push saltwater into coastal agricultural fields. This phenomenon, known as saltwater intrusion, alters nutrient cycling and damages crop yields. As sea levels continue to rise, saltwater intrusion will only worsen, with devastating consequences to agroecosystems along the coast of the Chesapeake Bay. Researchers and farmers alike are looking for solutions to adapt to and mitigate the effects of saltwater intrusion. Landowners may respond by altering their management practices. Farmers may 1) adapt by planting a salt-tolerant crop, 2) attempt to remediate soils with trap crops, 3) restore native marsh grasses, or 4) abandon fields altogether. My project investigates the survival of different crops and plant treatments under saltwater-intruded conditions and the potential for these plants to survive and to remove excess nutrients (e.g. sodium and phosphorus) from the soil, with the overall goal to benefit both the farming community and water quality in the Chesapeake Bay. Results from this study will help inform new management practices to increase soil health and maintain crop yields. Finally, the goal of this work is to guide local best management practices and potential easement opportunities for landowners facing saltwater intrusion, and ultimately determine optimal strategies for climate resilience.Item SURVIVAL OF ESCHERICHIA COLI AND CHANGES IN PHYSICOCHEMICAL PARAMETERS IN AQUAPONIC SYSTEMS DURING BASIL AND LETTUCE PRODUCTION(2023) Quach, Emily; Yonkos, Lance; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Aquaponics (APs), a soilless production system, integrates aquaculture and hydroponics to provide local fresh produce while conserving natural resources. The absence of soil in APs eliminates one potential food safety risk present in typical soil-based production systems, but APs may become contaminated from a variety of sources. Escherichia coli TVS 354 long-term survival was evaluated in bench-scale, deep-water APs units. In addition, pathogen presence on basil and lettuce at the time of harvest and changes in the population density of mesophilic aerobic bacteria in APs were measured. Results showed E. coli populations significantly decreased 24 h post-inoculation in water samples and remained undetectable by day 1 post-inoculation. Lettuce harvested on day 60 had detectable E. coli on lettuce leaves and roots at harvest. These results provide new insight on E. coli survival in harvested plants, indicate potential risks for foodborne illnesses, and unreliability of water testing as a monitoring tool.Item SPRAY STRATEGIES AND SELECTION FOR FUNGICIDE RESISTANCE: FENHEXAMID RESISTANCE IN BOTRYTIS CINEREA AS A CASE STUDY(2023) Boushell, Stephen Carl; Hu, Mengjun; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Fungicide resistance is a limiting factor in sustainable crop production. Despite the wide adoption of general resistance management strategies by growers, the recent rate of resistance development in important fungal pathogens is concerning. In this study, Botrytis cinerea and the high-risk fungicide fenhexamid were used to determine the effects of fungicide dose, tank mixture, and application timing on resistance selection across varied frequencies of resistance via both detached fruit assays and greenhouse trials. The results showed that application of doses lower than the fungicide label dose, mixture with the low-risk fungicide captan, and application post-infection seem to be the most effective management strategies in our experimental settings. In addition, even a small resistant B. cinerea population can lead to a dramatic reduction of disease control efficacy. Our findings were largely consistent with the recent modeling studies which favored the use of the lowest possible fungicide dose for improved resistance management.