The Effects of Planting Population and Soil Fertility on Tar Spot of Corn

Undergraduate #35
Discipline: Biological Sciences
Subcategory: Plant Research
Session: 4
Room: Park Tower 8212

Evan Buckner - University of Arkansas - Fayetteville
Co-Author(s): Dr. Martin Chilvers - Michigan State University; East Lansing, Michigan

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Tar Spot disease on corn was first identified in Mexico by Maublanc in 1904 from the causal agent Phyllachora maydis and Coniothyrium phyllachorae with a subsequent identification of Mongraphella maydis by Muller and Samuels in 1984. However, in 2015 Ruhl identified the first incidence of Tar Spot disease in the United States in Indiana and Illinois, was caused only by Phyllachora maydis. Originally the aforementioned pathogens were thought to have all been in occurrence for each outbreak, but Ruhl only identified P. maydis in samples. With recent identification in Michigan in 2016, farmers reported a 50 bushel per acre loss with recent studies projecting up to 50 % yield loss in the United States. With hybrid resistance still developing and a limited use of fungicides, planting population and soil fertility emerge as possible ways to control and mitigate the spread of this disease. We hypothesize that by having smaller populations of corn this will slow the spread of the disease infection and applying low rates of nitrogen will not induce pathogenicity. For both experiments, 3 trials were set up in Allegan and Montcalm County, Michigan with planting populations of 38, 46, and 70 thousand plants per acre and soil fertility trials with nitrogen rates at 80, 160, and 240 pounds of nitrogen per acre. Through using these methods, we hope to stabilize and further increase yield of corn from the Tar Spot disease. Preliminary yields or results have demonstrated that prior to infection plants with high nitrogen application are higher in stature than those with lesser rates and for population trials the actual stand count (plants growing) corresponds with the number of plants mentioned in the methodology. Further work is ongoing over a longer period time to determine the actual growth in these smaller populations and to compare this work with the previous work done in Indiana and Illinois.

Funder Acknowledgement(s): Michigan Corn Growers Association; United States Department of Agriculture; Michigan State University Graduate School

Faculty Advisor: Martin Chilvers, chilvers@msu.edu

Role: While working in the Martin Chilvers Lab I helped to write a methodology for the cultural practice research used, calculated all soil fertilizer calculations, and applied rates of nitrogen to two different Michigan counties. Also, I conducted stand counts (amount of plants growing) for four separate populations of plants in the two counties.