Verticillium Wilt: How to Identify and Manage It

Verticillium wilt is a soil-borne fungus that gets in through the roots and clogs the plant’s water pipes. The result is sudden wilting, yellow lower leaves and dying branches, often in warm weather. There’s no spray that cures it, so it’s worth being sure before you dig out a treasured plant.

Lots of plants can catch it. Acers, cotinus, catalpa and cercis are the woody plants hit most often, and tomatoes, potatoes, strawberries, roses and chrysanthemums can get it too.

What is verticillium wilt and what causes it?

It’s caused by fungi called Verticillium that live in the soil. They can sit there quietly for years as tiny resting bodies, waiting for the roots of a plant they like.

Once inside a root, the fungus grows up into the plant’s water pipes and blocks them. That’s why an infected plant looks thirsty even when the soil is damp. In warm weather, when the plant needs most water, the branches wilt.

It tends to show up most in mid-summer, and it’s happy in most soils. The RHS verticillium wilt page has the latest list of plants it affects.

How do I spot verticillium wilt?

The tell-tale sign is wilting on one side. One branch, or half the plant, wilts and browns while the rest stays healthy. Drought, by contrast, usually affects the whole plant.

Half a canopy wilting is a warning sign on an acer. It isn’t proof on its own, as root damage and other diseases can look similar.

Leaves usually go yellow from the bottom of the plant upwards, often with brown patches. Trees may put out small leaves in spring that then brown and die by midsummer. Some trees lose a branch or two each year before the whole thing struggles.

Cut across a freshly wilted stem with a sharp knife, and slice one lengthways too. Verticillium often leaves brown or black marks just under the bark, as part of a ring or as streaks. It’s a good clue, but not a guarantee, as other problems can stain the wood too.

Brown or black marks just under the bark point towards verticillium. For a valuable tree, get an expert opinion.

In soft plants like tomatoes and strawberries, look for streaks in the crown and lower stems. On trees, check younger branches, as streaks are easier to see there than in an old trunk.

Which UK garden plants does verticillium wilt affect?

It can hit a huge range of plants, but some get it far more often. Knowing the usual suspects helps you judge what’s going on.

Trees and shrubs: Acer, cotinus, catalpa and cercis are the most common. Roses, berberis and sumach can get it too. Our Japanese maple guide covers where to plant acers and how to look after them.

Fruit and veg: Strawberries, tomatoes, potatoes, aubergines, peppers and raspberries are all prone. Strawberry beds planted where potatoes or tomatoes grew before are especially at risk.

Cotinus is one of the shrubs verticillium hits most. Watch for a single branch wilting in summer even though the soil is damp.

Why do trees die slowly from verticillium wilt?

Trees often go downhill over several years rather than all at once. That slow decline is why it’s easy to miss early on.

In the first year, one branch may wilt and die back while the rest looks normal. The tree tries to wall off the fungus, and sometimes it succeeds and carries on for years.

More often, a few more branches fail each summer. The canopy thins and the leaves get smaller. Once half the tree is dead, it’s unlikely to recover.

Because it’s slow, it can be mixed up with drought or root damage. Brown streaks in a plant that’s known to catch it make the case stronger. For a valuable tree, a lab test is the safer way to be sure.

Good watering in dry spells and a mulch can help a lightly affected tree carry on. Bear in mind the soil underneath is building up more of the fungus, which matters for what you plant next.

How does verticillium wilt spread in the garden?

It travels in soil, not on the wind. It moves around in soil, infected plant bits and water.

As infected roots and stems rot, they release tiny resting bodies into the soil. You can’t see them, and they sit mostly in the top layer where roots grow.

They hitch a ride on boots, spades, wheelbarrows and mowers. Compost made from infected plants spreads it too, and so can water running downhill between beds.

New plants can bring it in. Strawberry runners, seed potatoes or nursery trees can carry it without looking ill. Buy from good suppliers and check the roots before planting. Wet, poorly drained soil makes soil diseases worse, so our soil drainage guide is worth a read.

Can I cure verticillium wilt in my garden?

No, sadly there’s no cure. No fungicide reaches the fungus inside a living plant, and there’s no practical way to clean it out of garden soil.

Knowing that saves you money on things that won’t work. Here’s what does help.

Remove badly affected plants promptly. Cut them down and dig out as much root as you can. Don’t put them on the compost heap. Bag and bin them or take them to the council green waste. The sooner they go, the less fungus ends up in the soil.

Don’t replant with something that catches it. The fungus can hang around for years. The RHS suggests grassing over a confirmed spot for at least 15 years, or choosing a resistant plant.

Look after your soil. Healthy, well-drained soil full of organic matter helps plants cope. Improving clay soil with compost and grit is a good place to start.

What should I plant instead?

Choose a plant on the RHS resistant list. Don’t just pick something that looks similar and hope.

Trees to replace a lost acer: Birch gives a light canopy and lovely bark. Beech, sweet gum (Liquidambar) and willow are also resistant, and conifers don’t get it. Avoid cercis, as it catches it readily.

For a lost cotinus, pick from the resistant list too. Then match the new plant to the light, soil and space you have.

Rotate your veg: Give affected beds a break from tomatoes, potatoes, peppers, aubergines and strawberries. Grow onions, leeks and sweetcorn there instead, as they don’t get it. Our crop rotation planner makes this easy.

How do I protect strawberries and tomatoes?

Grow them in fresh ground or fresh compost. Both crops are prone, and growing them in the same spot every year lets the fungus build up.

Strawberries: Plant certified healthy runners in ground that hasn’t grown potatoes, tomatoes, peppers or strawberries for a few years. Move the bed to fresh ground every three years or so. Raised beds or containers of new compost get round the problem entirely. Our strawberry growing guide covers choosing and planting.

Tomatoes: Grow bags or big pots of fresh compost each year keep them away from soil-borne fungus. For greenhouse borders, grafted plants on a resistant rootstock are a good option. Some seed packets mark varieties with “V” or “Ve” to show verticillium resistance. Our tomato diseases guide covers other problems, including the similar fusarium wilt.

Potatoes: Don’t grow potatoes in the same bed more than once every four years.

Fresh compost gets round soil-borne wilt entirely. Raised beds for strawberries and big pots for tomatoes keep both away from old ground.

Does covering the soil with plastic help?

It can help a little in a hot summer, but it’s no fix. The idea, called solarisation, uses the sun’s heat to cook fungus in the top layer of soil.

Dig the bed over, water it well, then stretch clear polythene tightly over it and bury the edges. Leave it for six to eight weeks in the hottest part of summer. It works best on light, sandy soil in the south, and less well in cooler parts of the UK.

It only reaches the top few centimetres, so some fungus survives below. Use it alongside rotation, resistant varieties and plenty of organic matter, and only on veg beds or strawberry plots.

Frequently asked questions

What does verticillium wilt look like?

Sudden wilting and dying branches are the main warning signs. Lower leaves often yellow, and one part of a shrub or tree can wilt while the rest looks fine. Brown or black streaks under the bark back this up, but other problems can look similar. Get it checked before you remove a valuable plant.

How long does verticillium wilt survive in soil?

For many years, sadly. The RHS suggests grassing over a confirmed spot for at least 15 years, or planting something resistant instead. Try not to carry soil from the area on tools, boots or the wheelbarrow.

Can I cure verticillium wilt?

No, there’s no cure. No fungicide for gardeners can reach the fungus inside the plant. Some lightly affected trees hang on for years, but most slowly decline. Remove badly affected plants, don’t compost them, and replace them with something resistant.

Which trees resist verticillium wilt?

Conifers, plus several broadleaved trees. Good choices include birch, katsura, hawthorn, beech, honey locust, sweet gum, mulberry, plane and willow. Avoid cercis, which catches it easily, as a replacement for a lost acer or cotinus.

Does verticillium wilt affect strawberries?

Yes, strawberries are very prone to it. Plants wilt and collapse, starting with the outer leaves, and the crown shows brown streaks when cut. Ground that grew potatoes, tomatoes or chrysanthemums is a common source. Plant certified healthy runners in fresh ground or clean compost.

Can I replant in soil where verticillium wilt killed a plant?

Yes, but choose a resistant plant. Dig out as much of the old root as you can and avoid spreading the soil around. Conifers, birch, beech, sweet gum and willow are safer choices.

Is verticillium wilt the same as fusarium wilt?

No, they’re different fungi. Verticillium attacks hundreds of different plants. Fusarium wilt comes in separate strains, each attacking one kind of plant, so tomato fusarium only hits tomatoes. Both cause brown streaks in the stem, but verticillium more often wilts one side first.