Bean anthracnose

Colletotrichum lindemuthianum Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara, 1889 · formerly or also: Glomerella lindemuthiana (sexual stage)

antracnosis del frijol · Spanish, Latin America
antracnose do feijoeiro · Portuguese, Brazil
anthracnose du haricot · French, France and Africa

Bean anthracnose is a seed-borne fungal disease that causes dark red to black streaks along the veins on the undersides of bean leaves, and sunken, dark-edged spots on pods, often with pinkish spore masses in the centre. Infected seeds carry the fungus into the next crop. In cool, wet weather it can destroy whole crops, and it is one of the most important bean diseases in the highlands of Africa and Latin America.

Bean pods with sunken, dark-bordered anthracnose lesions. Photo: Howard F. Schwartz, Colorado State University, Bugwood.org -, CC BY 3.0 US, via Wikimedia Commons.

Type: Fungal disease · Fungus (ascomycete)
Classification: Fungi › Sordariomycetes › Glomerellales › Glomerellaceae
Main crops: Common bean, Green bean
Found in: Africa, Latin America, Europe and North America, Asia
Chemical groups: FRAC 11, FRAC 3, FRAC M05 (mode-of-action groups, not products)
Last reviewed: 2026-10-20

What causes bean anthracnose?

Bean anthracnose is caused by Colletotrichum lindemuthianum Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara, 1889, a fungus (ascomycete) (order Glomerellales, family Glomerellaceae).

Older or alternative scientific names: Glomerella lindemuthiana (sexual stage).

Where it occurs

Found wherever beans are grown, most damaging in cool, humid regions and highlands of Africa and Latin America, and in temperate regions where uncertified seed is used.

Region	Status
Africa	Widespread, especially in highlands
Latin America	Widespread, especially in highlands
Europe and North America	Present; controlled largely by certified seed
Asia	Present

Symptoms and identification of bean anthracnose

Anthracnose on lima bean pods: large brick-red to brown blotches. Photo: David B. Langston, University of Georgia, Bugwood.org, CC BY 3.0, via Wikimedia Commons.

The organism

A fungus that forms small cushion-shaped fruiting bodies (acervuli) with dark bristles, producing pink to salmon-coloured spore masses in humid weather. More than 100 races differing in virulence are known, so resistance must be matched to the local races. The fungus can stay alive inside infected seed for several years, which is how it travels between regions and countries.

Signs in the crop, stage by stage

Crop stage	What you see
Seedlings	Dark sunken lesions on seed leaves and young stems from infected seed; seedlings may collapse.
Leaves	Dark brick-red to black streaks along the veins on the undersides of leaves, later visible on top.
Pods and seed	Round, sunken, dark brown spots with dark borders on pods, often with pink spore masses; discoloured or spotted seeds.

Disease cycle of bean anthracnose

Life cycle of Bean anthracnose — diagram drawn by Laisha from the stages below. Durations depend on temperature.

The fungus survives in infected seed and in crop debris. Seedlings from infected seed develop lesions that produce spores, which are spread by rain splash, wind-driven rain, insects, animals and people working among wet plants. Repeated cycles spread the disease through the crop, and infected pods pass it to the seed.

Stage	Duration	Notes
Infected seed and debris	Between seasons	Seed is the main source.
Infection of seedlings and leaves	After several hours of wetness	Cool, wet weather.
Lesions with spore masses	About 6-10 days	Pink spores ooze in humid weather.
Pod and seed infection	Later in the season	Carries the fungus forward.

Temperature

Most severe at cool to moderate temperatures (about 13-26 °C) with high humidity and frequent rain.

Generations

Several cycles per season in wet weather.

Conditions that favour it

Infected farm-saved seed, cool and wet weather, frequent rain and wind-driven rain, working in wet fields, continuous bean cropping and susceptible varieties. Rain at flowering and pod filling is especially important because it leads to pod and seed infection.

Economic threshold level (ETL)

There is no numeric economic threshold; management is preventive, based on clean seed, rotation and resistant varieties.

Thresholds are local. They depend on crop price, control cost, variety and natural-enemy activity, so use the figure your local extension service publishes where one exists.

Damage and yield loss from bean anthracnose

Losses can reach the whole crop when infected seed is planted and the weather is cool and wet; infected seed loses market and seed value. Seedlings from infected seed act as starting points, so even a small share of infected seed can lead to a severe epidemic when the weather favours the fungus.

Monitoring

Inspect seedlings for dark lesions on seed leaves and stems, a sign of infected seed.
Turn leaves over to look for dark streaks along veins, and check pods for sunken spots during and after flowering.
Before planting, inspect seed lots for discoloured or spotted seeds and reject lots with many of them.

How to control bean anthracnose (integrated management)

Control works best as a sequence: prevent, monitor, then act only when a threshold or a risk forecast says so, using the least disruptive option that works.

Cultural control

Plant certified, disease-free seed; this is the most important single measure.
Rotate beans with non-legumes for two to three years and bury or remove crop debris.
Do not work in fields when plants are wet; avoid saving seed from infected crops.
Where seed is saved on the farm, keep seed only from pods without spots, and from plots where no anthracnose was seen.
Choose drier seasons or lower-altitude sites for seed production where possible, since dry conditions reduce seed infection.

Biological control

Some Trichoderma and Bacillus products have reduced anthracnose in trials; they are not reliable alone.

Host resistance

Many resistance genes (named Co genes) are known; resistant varieties must match local races, and combining genes gives more durable protection.

Chemical control of bean anthracnose — by mode-of-action group only

Laisha names chemical options only by their resistance-committee mode-of-action group (IRAC for insects, mites and nematodes, FRAC for fungi, oomycetes and bacteria, HRAC for weeds), never by active ingredient or product. What is registered differs by country and changes over time; the label and your local plant-protection authority decide what may be used, on which crop, at what rate and with what pre-harvest interval.

Seed treatments reduce seed-borne infection, and foliar fungicides protect crops during cool, wet weather. What is registered differs by country and changes over time; follow the label and your local plant-protection authority.

Scheme	Group	Mode of action	Notes
FRAC	11	Quinone outside inhibitors (QoI)	High resistance risk; use in mixtures.
FRAC	3	Demethylation inhibitors (DMI)	Medium resistance risk.
FRAC	M05	Chloronitriles (multi-site)	Protectant.

Resistance management

Rotate and mix groups and rely on clean seed and resistant varieties.

Look-alikes and how to tell them apart

Angular leaf spot — Angular spots between veins with dark spore tufts beneath, not streaks along veins.
Common bacterial blight — Water-soaked spots with yellow edges and greasy pod lesions, without pink spore masses.
Bean rust — Raised pustules with powdery reddish-brown spores.

Host range

Common bean and other Phaseolus species, such as runner and lima beans; occasionally cowpea and other legumes.

What is still uncertain

Race composition varies by region and changes over time.
The role of alternative hosts in survival is poorly understood.
Seed-health standards for anthracnose differ between national certification schemes.

Grow guides for its host crops

How to grow the crop well is the first line of defence. Laisha's free grow guides cover each crop from sowing to harvest:

How to grow Common bean How to grow Green bean

Not sure this is what you are seeing?Ask Laisha: describe the symptoms or send a photo, and get a reasoned first read with what to check next — for your crop, your stage and your region.Ask Laisha

Sources

Colletotrichum lindemuthianum (anthracnose of bean) datasheet — CABI Compendium. https://doi.org/10.1079/cabicompendium.14918
Colletotrichum lindemuthianum (COLLLD) — EPPO Global Database. https://gd.eppo.int/taxon/COLLLD
Bean anthracnose: Dry Beans Pest Management Guidelines — UC IPM. https://ipm.ucanr.edu/agriculture/dry-beans/bean-anthracnose/
Mixture of Colletotrichum lindemuthianum races in anthracnose resistance screening and its implication for common bean breeding — Tropical Plant Pathology (Springer). https://doi.org/10.1007/s40858-018-0219-z

Written by Laisha from the sources above, in its own words. This page is general reference, not a prescription: confirm identification locally and follow the label and your plant-protection authority.