Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Agricultural and Biosystems Engineering

First Advisor

Carl J. Bern


Two corn hybrids, one resistant the other susceptible to storage fungi, were harvested and hand shelled at 22% moisture, wet basis, and stored at this moisture in aerated bin units each containing 1000 g. For each corn hybrid, four Rovral fungicide treatments and a control treatment were applied prior to storage. Carbon-dioxide evolution was measured in each treatment as the index of grain-deterioration rate. The experiment was terminated when a 2.0% dry-matter loss in the susceptible hybrid untreated sample was observed. Development of fungi growth in the stored samples was observed by determining the percent of fungi infection by Aspergillus and Penicillium spp, visible fungi, and germination on subsamples of each differently treated unit;The resistant corn hybrid manifested a lower deterioration rate and fungi growth than did the susceptible hybrid. Samples treated with fungicide showed a highly significant reduction in grain-deterioration rate and fungi growth compared with untreated samples. The results show that Rovral fungicide is an effective suppressant of fungi growth in corn stored at high-moisture contents;Equations of CO[subscript]2 evolution versus time were utilized in a computer simulation model for 26 years of Des Moines, Iowa, weather data to simulate the effect of fungicide treatments on the production of carbon dioxide in stored high-moisture corn of different hybrids at ambient weather conditions. Allowable storage time (AST) in Wilcke's model (1985) was updated to 1989 and corrected to damage, hybrid, and fungicide multipliers. Simulation prediction showed that resistant corn hybrids suppressed fungi development, increased the AST, and reduced both fan energy use and airflow requirements compared to the susceptible corn hybrid under the same conditions. Also simulation prediction indicated that Rovral fungicide treatments are very effective in slowing down grain deterioration rate and fan energy use compared to untreated samples under the same conditions.



Digital Repository @ Iowa State University,

Copyright Owner

Sulaiman A. Al-Yahya



Proquest ID


File Format


File Size

284 pages