Pythium Root Rot in Soybeans


Pythium root rot in your home garden soybeans attacks the roots and stems of your plants. Unfortunately, this fungal infection has the potential to severely damage soybeans, leading to significant crop losses. Get to know the signs to look for as well as effective means of management to keep your crops healthy and productive.


Healthy, well-maintained home garden soybean plants have a greater chance of resisting and healing from pythium root rot compared to plants that are damaged or suffering from stress. Grow your soybeans in areas that offer full sunlight for best growth, according to the Purdue University Cooperative Extension Service. Soybeans thrive in moist, sandy soils.


Pythium root rot of soybeans is caused by a variety of fungal pathogens from the Pythium species. Through sporadic spreading primarily through water and wind, this soil-borne fungus attacks plants most prevalently in poorly drained soil, according to the University of Illinois Extension IPM. Excessively wet soil creates an environment in which spores can "swim" to infect roots and stems, according to the Alabama Cooperative Extension System.


Once under attack by pythium root rot, soybeans experience darkened stem bases that are often soft and heavy with fluid. Seeds and roots decay and damping off occurs, or soybean seedlings wilt and die or fail to develop at all, according to the University of Illinois Extension IPM. As the root system is destroyed, the plant can no longer absorb necessary water and nutrients, so foliage discolors and plant growth is stunted.

Natural Control

For natural control, plant quality, uninjured seeds in warm soil with temperatures that remain above 65 degrees Fahrenheit, according to the University of Illinois Extension IPM. Maintain extremely well-drained soil and avoid irrigation for approximately two weeks after planting as these younger seedlings are the most susceptible to damage.

Chemical Control

For chemical control of pythium root rot in soybeans, use a fungicide as a soil drench. Apply a chemical with the active ingredient metalaxyl, according to the Alabama Cooperative Extension System. Additionally, consider the use of a seed treatment with the fungicidal application containing the active ingredient mefenoxam. Contact your local county extension agent for specific control advice in your region; for the most effective chemical application, contact a licensed professional.

Keywords: pythium root rot, pythium rot soybean, soybean rot control

About this Author

Tarah Damask's writing career, beginning in 2003, includes experience as a fashion writer/editor for Neiman Marcus, short fiction publications in "North Texas Review," a self-published novel, band biographies, charter school curriculum, and articles for eHow. She has a love for words and is an avid observer. Damask holds a Master of Arts in English and creative writing from the University of North Texas.