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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    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.
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    Biofilm formation by Escherichia coli O157:H7
    (2007-12-14) Silagyi, Karen Suzanne; Lo, Y. Martin; Kim, Shin-Hee; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Escherichia coli O157:H7 from cattle was evaluated for its ability to produce biofilm on food contact surfaces and quorum sensing signals in various raw meat, raw poultry, and produce broths. Generally, the strain was able to attach and form the most biofilm on stainless steel. Transfer of cells attached to stainless steel was observed onto various raw meat, raw poultry, ready-to-eat deli meats, and produce products as high as 104 CFU/cm2. E. coli O157:H7 isolated from 14 animal, food, and human sources were characterized on antimicrobial susceptibility, ability to form biofilm, and production of curli fimbriae and cellulose. Strains isolated from cattle, retail chicken, and retail beef were able to form strong biofilms in addition to curli and cellulose production. Additionally, E. coli O157:H7 from retail chicken showed considerable antimicrobial resistance. This study suggests E. coli O157:H7 biofilms pose significant risk to continuous contamination of a variety of food products.