Masters Theses

Date of Award

8-2020

Degree Type

Thesis

Degree Name

Master of Science

Major

Entomology and Plant Pathology

Major Professor

Heather Kelly

Committee Members

Bonnie Ownley, Tyson Raper

Abstract

Cotton seedling diseases are continuously associated with causing yield loss across the United States. To provide Tennessee cotton growers, and cotton growers across the southeastern portion of the cotton belt, with more accurate pathogen identification of soilborne diseases known to cause cotton seedling diseases, this project was carried out in conjunction with the National Cotton Seed Treatment (NCST) program. The aim was to identify populations of pathogens implicated in cotton seedling disease and evaluate seed treatment efficacy. Over the past 24 years, the NCST Treatment program has been conducted with the purpose of analyzing populations of soilborne pathogens known to cause cotton seedling diseases across the United States cotton belt. However, this data has only been collected using morphological identification for the species Thielaviopsis basicola, and Rhizoctonia solani, and identification to the genus level for species of Pythium and Fusarium. Several Fusarium and Pythium species can be difficult to identify with morphological features alone. Therefore, to generate a more accurate data set, Enzyme-Linked Immunosorbent Assay (ELISA) was used to identify Pythium and Rhizoctonia solani. Regarding pathogen populations in each field trial location, populations from 2018 were greater than those recovered in 2019. However, it can be argued that the 2019 data is more accurate due to the implementation of pathogen identification lab guides, new selective media, and ELISA identification in 2019. In addition to quantification of pathogen populations, the NCST trial analyzes the seed treatment efficacy against seedling diseases caused by these pathogens. Although sites and seed treatments varied between the 2018 and 2019 growing season, the control fungicide treatment, which controlled all pathogens of interest, increased stand over the nontreated check each year. In addition, locations in Alabama, Arkansas, Tennessee, and Texas had a significant overall stand response in both years.

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