Project Details:

Soybean Production Systems to Control Charcoal Rot and Other Soil-borne Diseases

Parent Project: Soybean Production Systems to Control Charcoal Rot and Other Soil-Borne Diseases
Checkoff Organization:Kansas Soybean Commission
Categories:Soybean diseases
Organization Project Code:1973
Project Year:2019
Lead Principal Investigator:Gretchen Sassenrath (Kansas State University)
Co-Principal Investigators:
Xiaomao Lin (Kansas State University)
Christopher Little (Kansas State University)
Kraig Roozeboom (Kansas State University)
Keywords: Charcoal Rot, cover crop, Macrophomina, Tillage

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Previous research sponsored by the Kansas Soybean Commission demonstrated that a high-glucosinolate mustard with biofumigant properties reduces M. phaseolina population levels in soil and in soybean plants. The research in this proposal builds on those results by developing management practices that incorporate use of mustard as a cover crop in soybean production systems, including double-cropped soybeans. Preliminary results indicate that tillage increases the charcoal rot fungus. The mustard cover crop will be tested in field studies for its impact on soil health, fungal disease presence, and soybean growth and yield. Controlled greenhouse studies will be performed to explore the mechanism of charcoal rot infection of soybean roots.

Project Objectives

1. Best management practices for implementing mustard seed cover crop.Mustard seed will be planted in the spring. Different methods of managing the mustard seed residue will be tested to determine the best method of controlling soil-borne fungal pathogens. Prior to planting soybeans, the field will receive a herbicide burndown. Four different methods (and one control) will be used to determine how to manage the soybean residue for optimal pathogen control, including:
> control (no mustard cover crop)
> no incorporation: plant into standing mustard
> no incorporation: cover crop rolled
> no incorporation: cover crop mowed
> incorporation: cover crop disked (tillage)
Soil samples will be collected prior to planting for determination of the pathogen. Soybeans will be planted and grown to maturity. Soil and soybean plant samples will be collected at the R7-R8 growth stage and measured for amount of fungus infection.

2. Mechanism of charcoal rot infection in soybean roots. Controlled growth studies will be conducted in the greenhouse to explore the mechanism of charcoal rot infection in soybean plants. Mustard will be grown to provide a biocontrol, and soil will be inoculated with M. phaseolina to provide high background amounts of the fungus. Soybean plants will be grown under environmental conditions that are conducive to high levels of infection.

Project Deliverables

Identification of cover crops for use in biocontrol of soil-borne diseases and development of guidelines for economical use of cover crops will assist producers in controlling fungal diseases in soybean. The impact of fungicide use on yield and net return will be determined, and guidelines developed. The interaction between soil health and fungal pressure will be assessed and alternative methods of improving soil health for optimal soybean production, yield components, and net return developed. The economic impact of management choices will assist producers in choosing economically viable production systems.
This research is a component of a research project exploring the mechanisms defining how soil health impacts crop production and plant disease. The research team has developed a proposal to leverage KSC funding with national funding through USDA-NIFA. The research is exploring the interactions between soil health and crop performance, developing alternative methods to control crop diseases and establish naturally disease-suppressive soils through cultural practices.
This research will also contribute to a study examining the potential for cover crops to control the soil-borne fungus Fusarium virguiliforme that causes sudden death syndrome, in collaboration with another Kansas Soybean Commission funded project (C. Little). Overall soil health and nutrient status will be measured in collaboration with Dr. Dorivar Ruiz Diaz.

Progress of Work

Updated July 2, 2019:
High-glucosinolate producting mustard was planted in replicated field plots at the Southeast Research and Extension Center research field near Columbus, KS and at the Agronomy Department research fields in Ashland Bottoms, KS in April, 2019. The mustard grew well at Ashland Bottoms. Although the cover crop initially germinated and grew well in Columbus, excessive rains flooded the field in Columbus, and we have no mustard cover crop. The research will continue at Ashland Bottoms only. Soil samples were taken in May for determination of colony forming units of the Macrophomina fungus, and measurement of phospholipid fatty acid analysis (PLFA) for soil microbial activity. Soybeans were planted in Ashland Bottoms after implementation of treatments. Additional mustard plantings were made in the greenhouse in the Department of Plant Pathology in Manhattan.

Updated September 9, 2019:
Soybeans were planted at Ashland Bottoms. Soil samples were collected for preliminary analysis of M. phaseolina colony forming units and microbial biomass. Mustard plantings made in the greenhouses are being used for background information on M. phaseolina performance. Soybeans will be harvested at maturity and final soil samples collected for analysis and CFU counts.

Updated December 11, 2019:
Plant and soil samples were collected at the R7 growth stage. The data are being analyzed for colony forming units of M. phaseolina. Soil samples were collected for determination of microbial parameters. Interesting differences in microbial biomass are observed for soil samples prior to planting soybeans and after soybean production (Figure 1). Control plots without mustard cover crop, and tilled plots, showed an increase in total microbial biomass at the end of the season that at the beginning. The more intact the mustard cover crop remained, the greater decrease in total soil microbial activity was observed. These changes in overall soil microbial activity will be related to differences in abundance of the disease organisms, M. phaseolina, in the soil and plants after analysis is complete.

Soybean yield was collected at harvest. These data will be analyzed when measurements are complete. Greenhouse studies have begun to delineate sensitivity of M. phaseolina to environmental conditions. Extracts of mustard plants have been collected to explore sensitivity of M. phaseolina to mustard.

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Final Project Results

Updated May 26, 2020:

View uploaded report PDF file

Charcoal rot fungus was reduced in plots using a high-glucosinolate mustard as a cover crop. The greatest reduction in disease was observed with minimal disturbance of the cover crop.

Benefit to Soybean Farmers

Charcoal rot, caused by the fungus Macrophomina phaseolina, (Tassi) Goid, limits yield and performance of soybean. The fungus is highly prevalent in crop fields in eastern Kansas. Certain plants have been shown to produce chemicals that act as biofumigants that control or reduce harmful soil fungi, such as that which causes charcoal rot. Bacterial control of diseases has been used successfully in potato production (Larkin et al., 2011). Mengistu et al. (2009) showed some suppression of charcoal rot infestation with reduced tillage and use of rye as a cover crop. The research outlined here will test the ability of mustard to control charcoal rot and other soil-borne pathogens in soybean production. The research will develop standard protocols for farmers to incorporate cover crops into current production practices. Incorporating a cover crop into the crop rotation may be a simple method of controlling soil-borne diseases while reducing use of fungicides that may contaminate the environment.
This research builds on previous research demonstrating that mustard reduces the number of CFUs of the charcoal rot pathogen. The research area will be expanded to include controlled environment studies in the greenhouses at Manhattan, KS to more fully explore mechanisms of charcoal rot infection. Experiments in other cropping systems at Parsons have indicated that soil microbial communities are modified by different varieties of the same crop. This research will complement a proposal submitted to USDA-NIFA to leverage KSC funds to explore the impacts of soil health and natural soil biocontrol methods on crop disease and productivity.

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