Date of Award


Degree Type


Degree Name

Master of Science (MS)


Botany and Plant Pathology

First Advisor

Kiersten A. Wise

Committee Chair

Kiersten A. Wise

Committee Member 1

William G. Johnson

Committee Member 2

Charles P. Woloshuk


Fusarium graminearum causes Gibberella ear rot in corn and produces mycotoxins such as deoxynivalenol (DON). Volunteer corn is a weed resulting from uncollected kernels from the previous harvest and is very difficult to control once established. An experiment was established in Porter County, IN from 2013 to 2015 to examine the impact of volunteer corn density on Gibberella ear rot severity and DON levels in hybrid corn. Five densities of volunteer corn were established within plots of each hybrid (0, 0.5, 2, 4, and 8 volunteer plants/m2). Disease severity and DON were assessed for both hybrid and volunteer ears collected at harvest. Combined grain was also tested for DON. Disease severity was very low across all three years, and no effect of volunteer corn density on disease severity was observed. Significantly higher levels of DON were observed in volunteer corn samples compared to hybrid corn samples and combine corn samples in 2013 and 2014 (P=0.0265 and P=0.0484, respectively). Yield decreased significantly with an increase in volunteer corn density in all three years (P<0.0001, P=0.0040, and P=0.0325, respectively). A second experiment was established in Tippecanoe County, IN in 2014 and 2015 to examine the impact of corn plant generation on disease severity, DON, and yield. The F1 and F2 generations of six hybrids were planted in 2014 and increased to nine hybrids in 2015. Disease severity, DON and yield were measured. DON differed significantly between generations in 2015 (P=0.0340) and yield was affected in both years (P=0.0063 and P=0.0062, respectively). Results from both studies indicate that volunteer corn is at least as likely as hybrid corn to be affected by DON and develop Gibberella ear rot, and is able to reduce grain yield when present at high densities.