Root rot is a disease of both houseplants and outdoor plants. It happens when the plant has to stand in soil that does not drain well. This leaves the soil wet and encourages pathogens which attack the plant’s roots. When the roots are infected, they can’t get the proper nourishment to the plant. Leaves wilt and become discolored. Eventually, the plant dies. When it’s pulled up, the roots are brown and rotten. Seedlings that have sprouted and seem healthy suddenly fall over, and the gardener sees that they are rotted at the soil line.
There is no cure for root rot. The plant needs to be pulled up and destroyed.
Preventing Root Rot
Keep the Ground Dry
The only way to deal with root rot is to prevent it. This means not watering the plant until the soil is dry. In an area where it rains frequently, the ground needs to be kept dry, and wet soil needs to be turned to allow water to evaporate. A good population of earthworms can also prevent root rot.
Depressions in the garden that won’t drain well and hold water should be filled in, and the soil needs to be amended with perlite or mulch to help it to drain well. Watering plants before noon let them dry off in the afternoon and discourages the fungi that cause root rot. Plants should be watered from below. This keeps the fungi from being spread through water that splashes on the leaves.
Practice Good Hygiene
The gardener should try to avoid touching wet plants, for this can also spread disease. They should wash their hands after they’ve handled plants that they believe are sick and disinfect gardening tools.
If the gardener believes that the soil is harboring a fungus that causes root rot, one remedy is to shallow-plant seedlings. This encourages them to germinate early and gives them a better chance to survive. There should be good air circulation around the plants, and the gardener should employ three to five-year crop rotations.
Solarizing means heating the soil to around 130 to 140 degrees Fahrenheit over several weeks. Higher temperatures can kill beneficial organisms. To do this, the gardener loosens the soil in the middle of summer, drenches it with water and leaves it undisturbed overnight. The next day, the gardener covers the soil with clear plastic that is secured with rocks or bricks at the edges. They then let the soil heat up for about a month or a month and a half. Then, the plastic is removed and the gardener plants as usual.
There are fungicides that can kill the disease-causing fungi, but the gardener needs to be sure that they use the fungicide made specifically for the organism that’s the source of the problem. The gardener can send a soil sample and a part of a diseased plant to their local cooperative extension. Agents at the extension can identify the fungus and tell the gardener how best to defeat it.