The Potential for Cereal Rye Cover Crops to Host Corn Seedling Pathogens

Area of Science:

• Agricultural Science
• Plant Pathology
• Soil Science

Background:

• Cover cropping, a conservation practice, improves soil and water quality.
• Winter cereal cover crops before corn may reduce crop rotation benefits due to successive grass species.
• Rye cover crops can potentially harbor pathogens detrimental to subsequent corn crops.

Purpose of the Study:

• To investigate if rye cover crops host pathogens that cause corn seedling disease.
• To quantify pathogen densities in rye roots and their impact on corn seedlings.
• To assess the influence of time and field conditions on pathogen load.

Main Methods:

• Isolation and identification of fungal and oomycete pathogens from rye roots.
• Pathogenicity assays on corn seedlings using isolated pathogens.
• Quantification of pathogen densities in rye roots over time in field experiments.
• Comparison of pathogen densities on corn seedling radicles after rye cover crop versus winter fallow.

Main Results:

• Fusarium graminearum, F. oxysporum, Pythium sylvaticum, and P. torulosum were isolated from rye roots and confirmed pathogenic to corn seedlings.
• Pathogen load in rye roots varied significantly across different fields and years.
• Pathogen densities on herbicide-terminated rye roots increased over time in at least one field.
• Corn seedlings following rye cover crops exhibited higher root pathogen densities than those following winter fallow.

Conclusions:

• Rye cover crops can serve as hosts for pathogens that cause corn seedling disease.
• The potential for rye to increase corn seedling pathogen loads is widespread.
• Effective management practices are crucial to mitigate seedling diseases and realize yield benefits from cover cropping.