Crown rot is a disease of the most vulnerable part of a plant: the crown, where the stem meets the roots at the soil line. It is the junction through which all water and nutrients pass, and when it rots, the whole plant fails at once. The leaves wilt and yellow, the stem base turns dark and soft, and the plant collapses or pulls out of the soil with almost no resistance, because the connection between the roots and the top has rotted away. It is a sudden, complete failure, and it is particularly disheartening because the plant often looks healthy until the day it falls over.
Crown rot is caused by several soil organisms, most often Phytophthora and Rhizoctonia, along with Fusarium and other fungi, and they all share a love of wet soil and a buried crown. The disease is worst where the soil stays wet, where plants are set too deep, and where mulch is piled against the stem, because all of these keep the crown damp and airless. It attacks a wide range of plants, from strawberries and rhubarb to trees and shrubs, and it is a major problem in heavy, poorly drained soil. The control is almost entirely about the conditions at the crown: drainage, planting depth, and keeping the base of the plant dry and clear.
What crown rot looks like: symptoms
- Wilting in wet soil: the plant wilts even though the soil is moist, and watering does not perk it up, because the crown can no longer transport water.
- Dark, soft tissue at the crown: the stem base and the crown turn brown or black and feel soft and mushy when pressed, often with a clear line between the rotted tissue and the healthy tissue above.
- Yellowing and collapse: the leaves yellow from the bottom up, the plant stops growing, and it may collapse suddenly or pull out of the soil with almost no resistance.
- A foul or musty smell: the rotted crown often smells musty or sour when the plant is lifted, which is a useful clue.
- Roots that look healthy: in crown rot the roots themselves may look relatively normal, which distinguishes it from root rot, where the roots are the rotted part.
- Stunting and poor yield: plants that are infected but not yet collapsed grow slowly, flower poorly, and produce little fruit.
- Death of the whole plant: in severe cases the plant dies outright, often within days of the first wilting, because the crown is the plant's lifeline.
Crown rot usually starts quietly, with the fungi invading the crown through a wound or through tissue that is kept constantly wet. The first above-ground sign is often a slight wilting on a warm afternoon, which is easy to mistake for a plant that needs water. Over the following days the wilting becomes permanent, the leaves yellow, and the stem base darkens and softens. In warm, wet soil the collapse can happen within a week of the first wilting; in cool soil it may take a month. Once the crown is rotted through, the plant cannot recover, because the connection between the roots and the top is gone. The disease is worst in spring and autumn, when the soil is cool and wet, and in beds that stay waterlogged after rain.
Which plants get crown rot
Crown rot attacks a wide range: strawberries, rhubarb, lettuce, tomatoes, peppers, cucurbits, beans, and many perennials, along with trees and shrubs such as apples, citrus, rhododendrons, and roses. Strawberries are the classic victim, and the disease is a major reason strawberry beds need to be replanted regularly and kept well drained. Lavender, rosemary, and other Mediterranean plants that expect sharp drainage are also prone when they are planted in heavy soil. The host range is wide enough that the disease is best thought of as a condition — wet crowns — rather than as a problem of any one plant.
Conditions that favour crown rot
Crown rot needs wet soil at the crown: heavy clay, compacted soil, poor drainage, and beds that hold water after rain all provide it. Planting too deep buries the crown in constant moisture, and mulching right against the stem does the same. Watering from above, especially in the evening, keeps the crown wet overnight. The organisms survive in soil and in plant debris, so a bed that has had crown rot before is at risk again unless the drainage is improved. Cool, wet weather favours the disease, and plants stressed by transplanting, by root damage, or by overfeeding are more easily invaded.
How crown rot spreads
Crown rot spreads through soil and water: in drainage water, in soil on tools and boots, and in infected plant material. It also travels in infected transplants and in nursery stock, which is a common way it reaches a new garden. The organisms survive in soil for years, so replanting the same crop into the same spot without improving drainage usually repeats the problem. It does not spread through the air, and insects are not a significant carrier. The practical rule is that anything carrying wet soil from an infected bed can carry crown rot.
How to tell it apart from lookalikes
Crown rot is often confused with root rot, but root rot rots the roots while the crown stays relatively firm, while crown rot rots the crown while the roots may look normal. Stem rot also darkens the stem base, but it usually starts above the soil line and moves upward, while crown rot is centred at the soil line itself. Cutworm damage severs the stem cleanly at the base and leaves the top beside the stump, while crown rot leaves a soft, dark, rotted crown. Drought wilting affects the whole plant evenly and recovers after watering; crown rot wilting does not.
Prevention: cultural steps that work
- Plant at the correct depth, with the crown at or slightly above the soil surface, never buried. This is the single most important step.
- Improve drainage with compost and coarse organic matter, and plant in raised beds or on slight mounds where the soil is heavy or wet.
- Keep mulch a few inches away from the stems and crowns so the base stays dry and air can reach it.
- Water at soil level, in the morning, and avoid wetting the crown and the lower stem.
- Use clean, healthy transplants from reputable sources, and do not bring in soil or plants from a garden with crown rot.
- Rotate crops so the same family does not return to the same bed year after year.
- Clean tools and boots after working in an infected bed, and work in healthy beds before infected ones.
Treatment step by step
- There is no cure for a plant whose crown has rotted through. Pull out the affected plant, with as much of the crown and roots as possible, and dispose of it with household waste — do not compost diseased material.
- Improve the drainage of the bed before replanting, by forking in compost, shaping a mound, or switching to a raised bed with fresh, clean mix.
- Do not replant a susceptible crop in the same spot this season. Plant a non-host crop there instead, or leave the bed fallow and improve it.
- Check the planting depth of the neighbouring plants and raise any that are set too deep, so their crowns are at the soil surface.
- Pull the mulch back from the stems of the remaining plants so their crowns stay dry and air can reach them.
- Water the remaining plants at soil level, in the morning, and cut back watering sharply while the soil is wet.
- Clean every tool, pot, and boot that touched the infected bed before using it elsewhere in the garden.
What recovery looks like
An infected plant does not recover from crown rot, because the rotted crown cannot be repaired. Recovery belongs to the bed and to the remaining plants: plants that were not yet infected may stay healthy if the drainage is improved, the mulch is pulled back, and the watering is corrected. The sign that the plan is working is a new planting that grows normally, with no wilting in wet soil and no dark, soft tissue at the crown when you check a plant at the end of the season. A bed that has been raised, limed, and drained, and that is planted at the correct depth, will usually stay free of crown rot even where the disease was a problem before.
When a plant is beyond saving
A plant is beyond saving once its crown is dark and soft right through, or once it has collapsed and pulls out of the soil with no resistance. A plant that is wilting in wet soil and shows dark tissue at the crown is also beyond saving, and removing it promptly protects the neighbours. A bed is not beyond saving — the disease is a condition of wet soil and buried crowns, and improving the drainage and the planting depth will usually fix it, though it may take a season of work to get the bed right.
Frequently asked questions
What is the difference between crown rot and root rot?
Root rot rots the roots, while crown rot rots the crown — the junction where the stem meets the roots at the soil line. In crown rot the roots may look relatively normal, while in root rot the roots are brown and mushy. The treatment is similar, but the distinction helps you work out whether the problem is the soil, the planting depth, or the mulch.
Can I save a strawberry plant with crown rot?
No. Once the crown has rotted, the plant cannot recover, and keeping it only lets the disease spread. Pull it out, improve the drainage, and replant with healthy runners in a fresh bed.
Why does crown rot hit my plants after heavy rain?
Heavy rain waterlogs the soil and keeps the crown wet for days, which is exactly what the organisms need. A bed that drains well will shed the water and stay healthy; a bed that holds water will lose plants after every heavy rain.
Does mulching cause crown rot?
Mulch piled against the stem can cause it, because it keeps the crown damp and airless. Mulch is still valuable — just keep it a few inches away from the stems and crowns, so the base of the plant stays dry.
Can I replant in the same spot after crown rot?
Not with the same crop, and not until the drainage is improved. Plant a non-host crop there, or leave the bed fallow and work in compost, and check your local extension service for advice on the rotation and the soil in your area.
Getting help and going further
If you are unsure which disease you are dealing with, take clear photos of the symptoms and check your local extension service — they can confirm a diagnosis from a sample and advise on the varieties and the timing that work best in your area. You can also try our plant disease checker to narrow down the problem, and browse the guides hub for related disease guides. For growing advice, see growing strawberries. For growing advice, see growing tomatoes. For growing advice, see growing lettuce. Related guides: root rot treatment, stem rot, damping off seedlings. Whenever you remove diseased material, dispose of it with household waste — do not compost diseased material, since home compost rarely gets hot enough to kill the organisms that cause these diseases. Good record-keeping helps too: note the date, the weather, and the variety when a problem first appears, so you can spot the pattern next year and act earlier.