Year of Publication

2018

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Plant Pathology

First Advisor

Dr. Carl A. Bradley

Abstract

Fungi in the genus Trichoderma have been characterized as biocontrol agents of plant pathogens since the 1930s. The use of biologicals for disease management has increased in recent years, typically marketed as a safer alternative to chemical applications. However, biologicals often lack consistent control across varying environmental conditions. To overcome the loss in efficacy due to environmental conditions, biologicals can be combined with common fungicide seed-treatments to provide improved control. Additionally, the presence of a biological organism could slow the development of a pathogen population. Greenhouse trials were conducted to determine the baseline root colonization of three Trichoderma spp. used in conjunction with five commonly used seed treatments. In field trials, a stand-alone treatment of the Trichoderma isolates was assessed for management of Rhizoctonia root rot (caused by Rhizoctonia solani) and frogeye leaf spot (caused by Cercospora sojina). The greenhouse trial provided evidence that isolates of T. virens and T. hamatum can colonize the roots of plants in which seeds were treated with metalaxyl + prothioconazole + penflufen or metalaxyl + prothioconazole + penflufen + fluopyram. Surprisingly, in the Rhizoctonia root rot trials, the soybean seedlings treated with Trichoderma spp. had significantly reduced stand compared to the R. solani inoculated control. For the frogeye leaf spot trial, an application of T. virens conidial suspensions as a foliar treatment significantly (P ≤ 0.10) reduced frogeye leaf spot severity of soybean compared to a non-treated control. Future research is warranted to better understand the potential efficacy in additional environments and the mechanism(s) of action used by the Trichoderma isolates evaluated in these experiments.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2018.414

Funding Information

North Central Soybean Research Program

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