Field monitoring, pathogen quantification, and greenhouse screening as a foundation for integrated management approaches for Pythium in corn
| Author(s) | Henrickson, Madeline G. | |
| Date Accessioned | 2025-07-01T15:51:35Z | |
| Date Available | 2025-07-01T15:51:35Z | |
| Publication Date | 2024 | |
| SWORD Update | 2025-06-21T10:05:33Z | |
| Abstract | Pythium root rot (PRR), caused by various species in the Pythium and Globisporangium genera, is an important early season disease in corn (Zea mays L.), particularly in the Mid-Atlantic region of the United States. Initial symptoms of PRR in corn include necrotic root tissue that may result in pre- or post-emergence damping-off, which can significantly reduce stand. Integrated pest management (IPM) is a comprehensive approach to pest control that uses cultural, physical, biological, and chemical methods to manage pests below an economic injury level. Current management practices for Pythium are either preventative and include the use of at-plant treatments, or reactive, involving complete replanting of affected fields in severe cases. This research aimed to build a foundation for IPM approaches for Pythium in corn through quantifying economic season-long impacts of PRR on surviving corn yield, assessing inoculation methods for controlled studies, investigating the suitability of qPCR to detect Pythium clades in soil samples, and evaluating current at-plant management strategies. Field and greenhouse studies were conducted to explore these methods. Plants that display early symptoms of Pythium infection can survive to reproductive maturity, but the economic impact is not well documented. A field study was conducted in 2021 and 2022 to track paired symptomatic and symptomless plants and quantify economic loss. Symptomatic plants had reduced root weight, stalk diameter and a 66% yield reduction compared to symptomless plants. Controlled environment inoculation trials identified Pythium-colonized sand-cornmeal as the most consistent inoculation method, and the use of rhizoboxes allowed for the visualization of root-pathogen interactions. Additionally, quantitative polymerase chain reaction (qPCR) was tested as a non-invasive tool for Pythium detection and quantification from soil samples. This technique could not differentiate Pythium abundance between soil collected 20 cm from the base of symptomatic versus symptomless plants. However, differences in Pythium density were noted across years, fields, and soil depths identifying utility of this approach for pathogen confirmation within fields and potential for development of diagnostic testing to compare risk across fields. To evaluate impacts of at-plant management, cover crop termination timing experiments showed increased seedling disease severity compared to a no cover crop control, with highest severity observed in plots with termination 3–7 days post planting. A greenhouse screening trial was conducted to evaluate the efficacy of one chemical seed treatment and two at-plant biological products, finding efficacy from picarbutrazox in two out of three experimental runs. These studies advance the understanding of PRR impact on corn while contributing to the development of IPM strategies that can improve PRR management in the Mid-Atlantic. | |
| Advisor | Betts, Alyssa K. | |
| Degree | Ph.D. | |
| Department | University of Delaware, Department of Plant and Soil Sciences | |
| Unique Identifier | 1526533430 | |
| URL | https://udspace.udel.edu/handle/19716/36309 | |
| Language | en | |
| Publisher | University of Delaware | |
| URI | https://www.proquest.com/pqdtlocal1006271/dissertations-theses/field-monitoring-pathogen-quantification/docview/3222859320/sem-2?accountid=10457 | |
| Keywords | Corn | |
| Keywords | Globisporangium | |
| Keywords | Integrated pest management | |
| Keywords | Maize | |
| Keywords | Pythium | |
| Keywords | Pythium root rot | |
| Title | Field monitoring, pathogen quantification, and greenhouse screening as a foundation for integrated management approaches for Pythium in corn | |
| Type | Thesis |