Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Root Rot

Problem
Leaves turn yellow. Overall growth is slow, and the plant may be dwarfed. In hot, dry weather the plant suddenly wilts and sometimes dies. Few pods are produced. Red spots or streaks may be seen on stems and roots. Underground stems may be streaked dark brown or black.

Analysis
This plant disease is caused by several soil-inhabiting fungi (Fusarium species, Pythium species, and Rhizoctonia solani) that attack beans and many other vegetables. The fungi live in the soil, invading the plant through the roots and underground stem. As the disease progresses, the roots decay and shrivel. The leaves turn yellow, and growth slows. The plant becomes dwarfed, wilts, and sometimes dies. Under favorable growing conditions, the bean plants may grow new side roots to replace the rotted ones. These plants will survive, but the yield will be reduced. Root rots develop most rapidly at soil temperatures between 60° and 85°F.

Solution
There is no completely effective chemical control for this problem. Pull out and discard wilted plants. Rotate your bean planting site yearly. If this is not practical, sprinkle with a fungicide containing captan or PCNB in the row at planting time (1 teaspoon per 20 foot row). Plant in well-drained soil and let the soil surface dry out between waterings. Avoid stress of any kind.

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