Crop Rotation Effects on the Population Density of Soybean Soilborne Pathogens Under a No-Till Cropping System

Area of Science:

• Agricultural Science
• Plant Pathology
• Soil Science

Background:

• Soilborne diseases pose a significant threat to soybean production.
• Crop rotation is a strategy for managing these diseases, but its effectiveness varies.
• Optimizing crop sequences is crucial for consistent disease control.

Purpose of the Study:

• To evaluate the impact of different long-term crop rotation treatments on soilborne pathogen populations in soybean fields.
• To identify specific crop sequences that can effectively suppress key soybean pathogens.
• To understand the relationship between environmental factors and pathogen dynamics within crop rotations.

Main Methods:

• A long-term no-till crop rotation field trial was established in South Dakota.
• Five distinct crop rotation treatments were implemented and compared.
• Quantitative PCR and egg extraction were used to quantify six major soilborne pathogens and soybean cyst nematode.

Main Results:

• Three pathogens (Macrophomina phaseolina, Fusarium oxysporum, Pythium irregulare) were detected; F. graminearum, F. virguliforme, and soybean cyst nematode were not significantly present.
• Crop rotation treatments influenced the population densities of the detected pathogens, with variations across crop phases, years, and pathogen species.
• Pathogen populations correlated positively with soil temperature and negatively with soil moisture.
• The corn-pea-winter wheat-soybean (CPWwS) rotation consistently showed lower Macrophomina phaseolina populations.

Conclusions:

• Specific crop rotation strategies can effectively manage soilborne pathogen populations in soybean production.
• The CPWwS rotation demonstrates potential for suppressing Macrophomina phaseolina.
• Understanding pathogen responses to crop sequences and environmental factors aids in developing sustainable disease management practices.