Doctoral Dissertations
Date of Award
8-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Entomology, Plant Pathology and Nematology
Major Professor
Heather Kelly
Committee Members
Heather Kelly, Bonnie Ownley, Lesley Schumacher, Ernest Bernard, Tarek Hewezi
Abstract
Taproot decline (TRD) of soybean is caused by the fungal pathogen, Xylaria necrophora, and is an emerging disease in the southeastern United States. To date, nothing is known about how the fungus progresses throughout the plant nor its interaction with other pathogens such as nematodes. Therefore, the first objective was to determine the exact nature of the relationship between X. necrophora and two economically significant plant parasitic nematodes of soybean: Meloidogyne incognita and Heterodera glycines, through both greenhouse and microplot trials. In greenhouse trials, plants treated with X. necrophora consistently had the highest average foliar disease ratings, M. incognita reproduction was highest in the presence of X. necrophora, whereas the inverse was observed with H. glycines. In microplot trials, egg and cyst recovery were low, making it difficult to determine the relationship between H. glycines and X. necrophora. Histological studies and RNA (ribonucleic acid) sequencing were used to supplement these investigations. The second objective was to investigate the effects of multiple soybean management decisions on plant parasitic nematode populations and soil fauna communities through a field trial using different cover crop mixes, seed treatments, and chemical burn down timings. Recovery of H. glycines eggs was greatest in 2021, and reproduction factor was variable across site years. Across all years, H. glycines reproduction increased in plots that had a cover crop mix containing brassica and soybean that was treated with an insecticide and fungicide combination treatment, soil organism reproduction was highly variable between years, and cover crops increased soil aggregate stability and soil respiration. Overall, the goal of this work is to help growers and researchers understand the underlying interactions that may impact soybean production and soil health factors.
Recommended Citation
Pate, Shelly, "INFLUENCE OF SOIL-BORNE FUNGI, PLANT PARASITIC NEMATODES, AND CULTURAL PRACTICES ON SOYBEAN YIELD POTENTIAL AND SOIL FAUNAL COMMUNITIES. " PhD diss., University of Tennessee, 2024.
https://trace.tennessee.edu/utk_graddiss/10412