Root Rot and Beans


Root rot is the most common problem when growing bean plants. If not prevented or taken care of it will destroy an entire crop. Having well-drained, nutrient-filled warm soil helps prevent the plant from getting a root-rotting fungi. Rotating crops regularly prevents the fungi from growing rapidly.

Common Root Rot

Fusarium solani is the most common cause of root rot in beans. This root rotting fungi lives in soil and thrives on composting vegetation. Plants are attacked when the fungus has multiplied to a high population of spores. Having poor soil, inadequate drainage and extreme weather conditions can cause the root rot fungi to spread rapidly.

Fusarium Root Rot

Fusarium root rot can be recognized by brick-red lesions, which later turn brown, on the main root of the bean plant. The infection and lesions can reach the soil line if not treated early. Heavily infected bean plants also have stunted growth and yellow foliage. The infection spreads rapidly to the branch roots, which are killed. The disease grows quickly in soils that are too compact, do not have enough drainage, or have low nutrients.

Rhizoctonia Disease

Rhizoctonia causes seedling disfigurement, root rot and stem lesions. Symptoms on roots are red to brown deep-cutting lesions surrounded by a halo of reddish-brown color. Left untreated the lesions grow bigger and become darker and rough. The fungus can cause a dark red color on the main part of the bottom stem. This disease is severe in short crop cycles of beans that are growing with sugar beet and potato, and also when soil temperature is low at planting.

Pythium Fungi

Pythium fungi distress seeds, seedlings and mature plants. Symptoms are long water-soaked areas on the roots. The infected area may be present well above the dirt line. Initially in the infection process the outer dermis of the stem comes off easily from the core of the roots and stems. It ultimately dries, and becomes thin, hollow and rots.

Cultivation of Fungi

When adequate moisture is accessible, lateral roots develop above the primary infected soil. Moving dirt closer to the base of the plant may initiate lateral root growth, thus giving the fungi more of an opportunity to develop on the plant. Moist soil, random watering, and high humidity encourage the fungi to reproduce quickly. When the soil becomes infected it needs to be completely dug out and replaced with fresh nutrient-filled soil in order for the infection to not spread to other plants.


Rotation is vital in controlling and preventing root rot infection among bean plants. Rotating plants every three to four years dramatically reduces the growth of these pathogens. Crops such as sunflower, potato, sugar beet and soybean maintain the endurance of the fungi, and should not be in a regular rotation when planting beans. Corn and small grains are excellent crops to grow in close rotation because they do not support the growth of the fungi.

Keywords: root rot, preventing root rot, root rot fungi

About this Author

Living in Southern California, Shayne Ochoa has been writing professionally since 2005. Her articles have included topics on education, child development and gardening. She also holds a Bachelor of Arts degree in liberal studies from California Baptist University in Riverside.