Choosing planting

Diseases and pests of broad beans

Identify, manage, and prevent pests of broad beans

Contents

Modified the 7 January 2026 by Pascale 5 min. Difficulty: Medium

There are many advantages to growing broad beans (Vicia faba var. faba) in your vegetable garden: it is a legume from the Fabaceae family, very rich in proteins and energy nutrients, making it ideal for a vegetarian diet. From April onwards, in regions with a favourable climate, its seeds can be enjoyed fresh. Fairly easy to grow in deep, moist, humus-bearing soil, broad beans are also beneficial for your garden soil: the nodosities on their roots have the ability to capture atmospheric nitrogen and return it to the soil. Growing broad beans thus enriches the soil with nitrogen.

However, it is a vegetable plant that can be susceptible to a few diseases and pests, among which aphids are the most well-known. So much so that sometimes broad beans are considered a martyr plant, a true magnet for aphids. Let’s discover together the main pests and diseases of broad beans, and especially how to identify, treat, and prevent them.

To learn more: Broad bean: sowing, growing, harvesting.

Difficulty

Ascochyta blight of broad bean

Formerly known as anthracnose, the ascochyta blight of broad beans is a fungal disease caused by the fungus Ascochyta fabae. The disease primarily develops in cool temperatures, around 10 to 15 °C, and with some humidity. This disease is more prevalent in the south of the territory.

The responsible fungi survive over winter on contaminated plant debris. Seed can also be contaminated.

Symptoms

Two to three light grey to ash-brown spots appear on the leaves in a rather diffuse manner. The spots then develop into streaks and become punctate with small black dots. The centre of the spot undergoes necrosis. This disease can also affect the collar and roots of the broad bean, significantly weakening the plant, which may eventually die.

Treatment

A spray of Bordeaux mixture can be applied at the first appearance of symptoms

Prevention

Carefully collect and destroy end-of-crop debris
Use healthy, disease-free seeds or new seeds
Do not keep seeds from diseased plants
Water at the base of crops rather than by spraying

For further reading: Anthracnose

Bean rust

Bean rust is caused by the fungus Uromyces viciae-fabae. It overwinters on the culms and on spontaneous regrowth of beans before being dispersed by the wind. This fungus generally attacks legumes, including faba beans, lentils, and vetch.

Symptoms

Small circular spots resembling pustules appear on the upper and lower surfaces of the leaves. The stem may also be affected. The disease causes stunted growth, and the leaves often turn yellow. Humidity is a factor in the development of the disease.

Symptoms of rust on a bean leaf

Treatment

Bordeaux mixture is used as a curative treatment at the first signs of the disease. It is also necessary to remove affected leaves, whether they are still on the plant or on the ground.

Prevention

Spray nettle manure on the soil before planting bean seeds
Plant sufficiently spaced to ensure air circulation between plants
Clean and disinfect gardening tools after each use

For further reading: Getting rid of rust disease

The bean downy mildew

Downy mildew is a cryptogamic disease caused by the fungus Peronosporea viciae, present in the soil and on seeds. Downy mildew develops in cool (between 10 and 15 °C), humid, and overcast conditions.

Symptoms

On the upper side of the leaves, discoloured areas appear, tinged with a slightly reddish-grey to almost black. A grey felt develops on the underside of the leaves. The leaves blacken, dry out, and sometimes curl. They eventually perish.

Treatment

The treatment will be the same as for rust: simply spray Bordeaux mixture at the first signs of symptoms. Destroying the affected parts is also important.

Prevention

Spray nettle manure on the soil before planting
Keep the soil well-tilled
Avoid growing broad beans in overly damp areas
Make preventive sprays of horsetail manure

Grey mould or botrytis of broad bean

The fungus Botrytis fabae is responsible for this disease. It has the ability to overwinter in the soil and on contaminated plant debris. It mainly develops in humid conditions during spring.

Symptoms

Small brown necrotic spots develop on the leaves. They enlarge and merge to form large areas of necrosis. The stems may be punctate with brown streaks, as can the pods or flowers.

Treatment

It is essential to uproot and burn the affected plants.

Prevention

Avoid using overly nitrogen-rich fertilisers
Grow broad beans in well-drained and deeply cultivated soil
Space the plants at least 25 cm apart to ensure good air circulation
Water the soil and plants in spring with a horsetail decoction
Stimulate the growth of the plants with nettle manure

For further reading: Botrytis or grey mould

The various pests of broad beans

Aphids are certainly the most common pests of broad beans. However, there are others, more or less common. All should be monitored, as they can cause considerable damage and impact yields.

The Black Bean Aphid

©Rasbak

Aphis fabea, a black aphid, particularly targets broad beans, often developing large colonies. Aphids concentrate on young shoots and forming pods, piercing them and sucking the sap. If attacks occur early, broad bean plants can be completely destroyed. However, aphids mainly affect the development of young shoots, causing them to curl, and the pods, which become stunted.

Aphids facilitate the onset of diseases.

To get rid of these pests, several solutions are available:

Spray the aphids with a strong jet of water to knock them to the ground
Remove infested stems
Make a spray of water mixed with black soap
Attract ladybirds, lacewings, or hoverflies, whose larvae are significant consumers of aphids. Simply plant melliferous flowers, leave some weeds, provide natural shelters (wood piles, stones, branches…) or build insect hotels. It is also possible to introduce ladybird larvae.

The Pea Weevil

The pea weevil (Sitona liteatus) is a light grey weevil. The insect flies in May and June during warm weather. It lays up to 100 tiny, invisible eggs on leaves and stems in October. The eggs, nymphs, and adults survive the winter.

diseases and pests of broad beans The pea weevil also attacks broad beans

The weevils eat the edges of the leaves, creating rounded notches. The larvae attack the roots, causing the plants to wilt.

To treat, it is possible to spray with an infusion of tansy or wormwood. For prevention, encourage rapid growth with nettle manure and apply a strict rotation of at least 2 to 3 years.

The Broad Bean Bruchid

Bruchus rufimanus is a beetle that lays its eggs on the surface of the pods in spring. Then, the larva burrows into the seeds of the broad bean and develops quietly for 3 months. It pupates inside the seed.

diseases and pests of broad beans The broad bean bruchid

Seeds punctured by the bruchid are not consumable. They can be easily identified by a small hole. The bruchid can infest seeds.

The only way to protect against the bruchid is to freeze the seeds for 24 hours. The cold kills them.

→ Learn more in our article: Bruchid of legumes, what is it? How to get rid of it?

The Pea Midge

Contarinia pisi is a small midge, 2 mm long, invisible to the naked eye, but whose flights can be seen in groups at the end of the day. Eggs are laid in May-June on young shoots or between the sepals, which thicken and curl under the action of the young larvae. The larvae of the second generation, red in colour, attack the inner wall of the pods. The pupae then spend the winter in the soil.

During flights, it is recommended to spray with an infusion of tansy or wormwood. Then, removing affected flowers helps prevent the second generation.

To prevent the appearance of the midge, a rotation of at least 2 years is necessary. It is also important to thoroughly remove crop debris.