Anthracnose is a disease with many faces, which is why it is so often misdiagnosed. On leaves it makes dark, sunken spots with pale centres. On stems and twigs it makes cankers that girdle and kill the shoot beyond them. On fruit it makes sunken, circular, rotting spots that spread as the fruit ripens. On a tree it can kill the twig tips in spring and thin the canopy. All of these symptoms are caused by fungi in the Colletotrichum group and their relatives, and all of them share the same wet-weather biology.

Anthracnose is a warm, wet-weather disease, worst in rainy summers and in humid climates, and it attacks a very wide range of plants: beans, cucumbers, melons, tomatoes, peppers, strawberries, grapes, mangoes, and many trees including sycamore, ash, oak, and dogwood. The fungi overwinter in infected twigs, fallen leaves, and seeds, and they spread in splashing rain. Like most leaf diseases it has no cure once it is inside the tissue, but it is very responsive to dry foliage, airflow, and the removal of infected material — and to choosing resistant varieties where they exist.

What anthracnose looks like: symptoms

  • Sunken dark spots on leaves: circular or irregular spots that are dark brown or black with a pale or grey centre, sometimes with a yellow halo, and sometimes with tiny black dots in the middle.
  • Sunken spots on fruit: circular, sunken, dark spots on fruit that enlarge as the fruit ripens, often with pinkish or salmon-coloured spore masses in the centre in wet weather.
  • Cankers on stems and twigs: sunken, dark, elongated spots on stems that can girdle the stem and kill everything beyond them.
  • Twig dieback on trees: shoot tips and young twigs die back in spring, leaves brown and hang on the dead twig, and the canopy looks thin and ragged.
  • Leaf drop: badly spotted leaves yellow and fall, starting with the lowest leaves.
  • Damping off and seedling blight: in beans and cucurbits, anthracnose can rot seedlings at the soil line and spot the seed leaves.
  • Spotted pods and seeds: on beans, the pods develop sunken dark spots with pale centres, and the seeds inside can carry the fungus to next year.

Anthracnose usually appears after warm rain, with the first spots showing on the lowest leaves and the youngest shoots. On annual vegetables it climbs the plant through the summer, with each rainy spell producing a new wave of spots and, on fruiting plants, a new wave of rotting fruit. On trees it is worst in spring, when the new growth is soft and the weather is wet, and it often eases by midsummer as the leaves harden and the weather dries — a sycamore that looked half dead in May can look almost normal by July. In a wet year the disease can destroy a bean or cucumber crop; in a dry year the same planting may show only a few spots.

Which plants get anthracnose

Anthracnose attacks beans, cucumbers, melons, squash, tomatoes, peppers, eggplants, strawberries, grapes, and many fruit trees, along with shade trees such as sycamore, ash, oak, maple, and dogwood, and ornamentals such as roses and hydrangeas. Each anthracnose fungus tends to specialise, so the form on beans does not usually attack cucumbers, but the range across the garden is wide enough that almost every gardener will meet one form or another. Trees are often the most dramatic victims, with spring twig dieback that can look alarming, though they usually recover by midsummer.

Conditions that favour anthracnose

Anthracnose needs warm, wet weather: temperatures in the 70s and 80s Fahrenheit with leaves wet for many hours. Rain splash is the main spreader, and the fungi overwinter in infected twigs, fallen leaves, seeds, and plant debris. Crowded, shaded plantings that dry slowly are hit hardest, and young, soft growth is more vulnerable than mature tissue. Wounds from insects, hail, or pruning give the fungi easy entry, and plants stressed by drought or poor nutrition are more badly affected. The disease is worst in humid climates and in rainy summers, and it is rare in dry regions.

How anthracnose spreads

Anthracnose spreads in splashing water — rain hitting an infected leaf or twig throws spores onto the tissue below and beside it — and on hands, tools, and clothing that touch wet plants. It also travels in infected seed, which is a major route for beans and cucurbits, and in nursery stock. The fungi survive the winter in cankers on twigs, in fallen leaves, and in debris, so the previous year's material is the usual source of the next year's outbreak. Wind carries spores over short distances, but water and contact are the main routes, which is why dry foliage and clean tools are effective controls.

How to tell it apart from lookalikes

Anthracnose is often confused with other leaf spots, but its sunken spots with pale centres and its tendency to attack fruit and stems as well as leaves are distinctive. Bacterial spot makes smaller, raised, scabby spots on fruit rather than sunken rotting ones. Sunscald makes pale, papery patches on the sun-facing side of fruit without a dark border. Blossom end rot makes a single dark, leathery patch at the blossom end of the fruit, not scattered sunken spots. On trees, anthracnose dieback can look like frost damage, but frost hits the whole canopy at once after a cold night, while anthracnose follows wet spring weather and shows spots on the leaves.

Prevention: cultural steps that work

  • Start with clean, disease-free seed and healthy plants from reputable sources, and do not save seed from infected fruit or pods.
  • Choose resistant varieties where they are available — many beans, cucumbers, and tomatoes have anthracnose-resistant varieties.
  • Space plants for airflow, plant in full sun, and water at soil level in the morning so foliage dries quickly.
  • Mulch to reduce splash, and avoid handling plants when they are wet.
  • Rotate crops so the same family does not return to the same bed for at least two to three years.
  • Prune trees for an open canopy so air moves through them and leaves dry after rain, and remove dead twigs in winter.
  • In autumn, rake up and dispose of fallen leaves and debris, and do not compost diseased material.

Treatment step by step

  1. Pick off spotted leaves and fruit as soon as you see them, and dispose of them with household waste. Do this in dry weather.
  2. Prune out infected twigs and stems, cutting back to clean wood, and dispose of the prunings rather than chipping them into garden mulch.
  3. Stop overhead watering and switch to watering at soil level, in the morning.
  4. Improve airflow by thinning crowded growth, and mulch the bed to reduce splash.
  5. If you choose to spray, a fungicide labelled for anthracnose on the plant in question can protect new growth, but it will not cure spots that are already there. Apply it to clean new foliage exactly as the label directs.
  6. Keep feeding steady and moderate so the plant can replace lost leaves, and avoid heavy nitrogen that pushes soft growth.
  7. At the end of the season, pull up annuals and clear all debris from the bed, and rake up fallen leaves under trees.

What recovery looks like

Recovery from anthracnose follows the weather: once the rain stops and the foliage dries, new leaves and new fruit should come through clean, and the plant will start to fill in again. Trees often recover dramatically, pushing out a second flush of leaves in early summer that replaces the blighted spring growth. On vegetables, the spotted leaves and fruit will not heal and should be removed, but the plant can go on to produce a reasonable crop from its later growth. The recovery is fastest when the infected material is removed promptly and the plant is given sun, air, and steady water. A plant that keeps its new growth clean for two weeks after the outbreak is on the way back.

When a plant is beyond saving

A plant is beyond saving from anthracnose when it has lost most of its leaves, when new growth keeps coming through spotted despite dry weather, and when the fruit is widely rotted. Annuals in that state are best pulled out and the bed cleared, since they will not produce a worthwhile crop. Trees and shrubs are rarely beyond saving from anthracnose alone — even a tree that loses most of its spring leaves usually releafs by summer, and the disease is a recurring nuisance rather than a killer unless it returns severely for several years running.

Frequently asked questions

Can I eat fruit with anthracnose spots?

Lightly spotted fruit can sometimes be salvaged by cutting away the affected part, but fruit with large sunken rotting spots should be discarded, and it is not worth keeping a plant for fruit that is mostly rotted. If you are unsure, check your local extension service.

Will anthracnose kill my sycamore or dogwood?

Rarely. Anthracnose defoliates trees in wet springs and kills twig tips, but most trees releaf by summer and survive for years with the disease. Repeated severe defoliation over many years can weaken a tree, so pruning and cleanup still matter.

Can I save seed from beans with anthracnose?

No. The fungus travels in and on the seed, so saving seed from an infected plant carries the disease into next year. Buy fresh, clean seed instead.

Why does anthracnose hit my cucumbers every year?

The fungus overwinters in debris and in the soil near it, and it returns in the first warm rain. Thorough autumn cleanup, rotation, resistant varieties, and watering at soil level are the ways to break the yearly cycle.

Is anthracnose the same on all plants?

No — anthracnose is a group of related fungi, and most forms specialise in one plant or a small group of related plants. The control is similar for all of them, but a bean anthracnose will not usually infect your tomatoes.

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 green beans. For growing advice, see growing cucumbers. For growing advice, see growing tomatoes. Related guides: leaf spot disease, early blight tomatoes, brown rot fruit. 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.