Fusarium root rot is caused by soil-borne pathogens and affects many vegetable plants, including beans, corn and sweet potatoes. The fungus causes roots to darken, crack and rot and interrupts normal root function. No chemical treatment is available for root rot, although good gardening practices will limit its spread.
In dry beans and snap beans, the roots turn reddish brown and may develop cracks. Above ground, bean plants appear stunted and may be light green or yellowish in color. Corn roots darken, shrivel and rot, reducing corn growth and yield. Root rot causes sweet potato roots to develop brown lesions which eventually spread. The roots may develop cavities containing white fungus. Eventually roots shrivel and become mummified.
Bean plants show symptoms two or three weeks after planting, while corn may not show symptoms until four or five weeks after planting. Root rot most commonly affects sweet potatoes after harvest. It is often introduced through injuries sustained during mechanical harvesting.
Fusarium root rot decreases yields, as well as crop quality. The pathogens that cause fusarium root rot affect both home gardens and commercial agricultural fields. For farmers, controlling root rot is especially important.
Prevention/Solution for Bean and Corn
Planting disease-resistant seed or seed treated with fungicide can minimize fusarium root rot. The best prevention, though, is the use of good cultural practices that encourage healthy, rapid root development, allowing plants to fight off disease. These practices include providing well-drained, loose soil, planting bean and corn seeds when the soil is at least 60 degrees Fahrenheit, keeping the soil evenly moist but not soggy, and rotating crops. The overuse of pesticides and fertilizer causes root damage, which leaves plants vulnerable.
Prevention/Solution for Sweet Potatoes
Although fusarium root rot may be present in the soil, it doesn't usually affect sweet potatoes unless they've received a mechanical injury during harvest. Occasionally nematode infestations may cause injury, making the plant susceptible to root rot. Hand harvesting to avoid root damage, managing nematodes and curing the sweet potatoes after harvest minimize root rot.