Cover crop and crop rotation effects on tissue and soil population dynamics of Macrophomina phaseolina and yield under no-till system

Authors: Mengistu, Alemu; Read, Quentin; SYKES, VIRGINIA - University Of Tennessee; KELLY, HEATHER - University Of Tennessee; Kharel, Tulsi; Bellaloui, Nacer

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2023
Publication Date: 2/28/2024
Citation: Mengistu, A., Read, Q.D., Sykes, V., Kelly, H., Kharel, T.P., Bellaloui, N. 2024. Cover crop and crop rotation effects on tissue and soil population dynamics of Macrophomina phaseolina and yield under no-till system. Plant Disease. 108:302-310. https://doi.org/10.1094/PDIS-03-23-0443-RE.
DOI: https://doi.org/10.1094/PDIS-03-23-0443-RE

Interpretive Summary: The effects of crop rotation and winter cover crops on the fungus that causes charcoal rot disease on soybean in soil, stem and root tissues and yield are poorly understood. Field trials were conducted in 2011 and 2015 to evaluate the impact of crop rotation consisting of soybean following cotton, soybean following corn and continuous soybean planting from 2011 through 2015. Cover crop treatments consisted of winter wheat, Austrian winter pea and hairy vetch, poultry litter, and a fallow. Our result showed that the severity of the disease varied significantly between years, with greater levels observed in 2015 as compared to 2011. In addition, plots with poultry litter had significantly higher disease severity in tissue than plots where hairy vetch was grown as a cover crop. Yield was much greater in 2015 compared to 2011. A greater yield was observed in plots planted following cotton in the rotation in 2015, but not in 2011. The result from the continuous soybean planted over five years showed no significant effects of any of the cover crop treatments, nor was there interaction between treatment and year on yield. The lack of significant interaction in crop rotation and between cover crop treatments suggest that cover crop recommendations for mid-southern soybean growers may need to remain separated and be based on long term crop needs, regardless of the rotation system.

Technical Abstract: The effects of crop rotation and winter cover crops on soybean yield and colony forming units of Macrophomina phaseolina, the cause of charcoal rot (CR), are poorly understood. A field trial was conducted from 2011 to 2015 to evaluate 1) the impact of crop rotation consisting of soybean (Glycine max (L.) following cotton (Gossypium hirsutum L.), soybean following corn (Zea mays L.) and soybean following soybean over a two-year rotation and 2) the impact of planting continuous soybean crop over a five-year period with both 1 and 2 crossed with cover crop. Cover crops consisted of winter wheat (Triticum aestivum L.), Austrian winter pea (Pisum sativum L. sativum var. arvense), hairy vetch (Vicia villosa Roth) and a fallow with and without poultry litter application. Two separate analyses were made on data with and without crop rotation. Tissue colony-forming units (CFU) of CR varied significantly between years, with greater levels observed in 2015 as compared to 2011. Plots with poultry litter had significantly greater tissue CFU than plots with wheat cover crop. In addition, plots where soybean was grown following cotton also had significantly greater tissue CFU than plots following soybean. Contrary to tissue CFU, soil CFU in 2015 was substantially lower compared to 2011. However, plots in the fallow treatment had significantly greater soil CFU than plots where hairy vetch was grown as a cover crop. Yield was much greater in 2015 compared to 2011. There was a significant interaction of previous crop in the rotation with year, with a greater yield observed in plots planted following cotton in the rotation in 2015, but not in 2011. The result from the continuous soybean planted over five years showed that there were no significant effects of any of the cover crop treatments, nor was there interaction between treatment and year on yield. The lack of significant interaction between treatments in the first analysis and the absence of significant differences between cover crop treatments in the second analysis suggest that cover crop recommendations for mid-southern soybean growers may need to remain separated and be based on long term crop needs, regardless of the rotation system.