Agronomy and Horticulture, Department of


First Advisor

Gary Y. Yuen

Date of this Version


Document Type



Muhle, Anthony A., "Rust and viral mosaic diseases in biofuel switchgrass" (2019). Thesis, Dissertations, and Student Research in Agronomy and Horticulture.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agronomy, Under the Supervision of Professor Gary Y. Yuen. Lincoln, Nebraska: August 2019.

Copyright (c) 2019 Anthony A. Muhle


Switchgrass (Panicum virgatum L.) is a perennial warm-season monocot that is indigenous to locations in North America east of the Rocky Mountains, and is considered a model grass for biofuel feedstock production. As switchgrass production increases, diseases pose a potential threat to biomass production and ethanol extraction. The two predominant switchgrass diseases in Nebraska are rust caused by Puccinia spp. and a viral mosaic disease caused by Panicum mosaic virus (PMV) and its associated Satellite panicum mosaic virus (SPMV). In this thesis, one study determined how SPMV affects PMV infection and systemic spread in two populations of switchgrass at different temperatures under controlled conditions. The results from this study showed that no synergism from co-infection of PMV and SPMV occurred in switchgrass cvs. Kanlow and Summer. The study also indicated that both cultivars can equally be infected by PMV alone and the combination of PMV+SPMV, but Kanlow suppressed systemic spread of the viruses. Temperature had no effect on systemic spread of the viruses, although there was some evidence that higher temperature may have an effect on the initial infection of switchgrass plants by the PMV+SPMV combination. Another study evaluated hybrid switchgrass populations that originated from crossing of Kanlow (lowland ecotype) and Summer (upland ecotype) for their responses to rust and viral mosaic diseases under Nebraska field conditions. The results indicated that there was large variation among switchgrass hybrid populations as to their response to rust and viral mosaic severity ratings, with populations exhibiting high resistance comparable to Kanlow and other populations exhibiting susceptibility similar to Summer. Also, there was a significant positive correlation between parent and progeny populations as to their response to rust and viral mosaic diseases. However, there was no linkage found between resistance/susceptibility to rust and resistance/susceptibility to viral mosaic. Nevertheless, hybrid populations with resistance to both rust and viral mosaic diseases were identified, these populations being excellent candidates for use in further development of biofuel switchgrasses.

Advisor: Gary Y. Yuen