Important diseases and pests of faba beans

The following article shows which diseases and pests frequently occur in field beans, the symptoms by which they can be recognised and the options available for combating them.

The faba bean (Vicia faba), also known as broad bean or horse bean, is cultivated for both human and animal consumption. Botanically, it belongs to the vetch genus (Vicia). Like other legumes, the field bean has a high crude protein content and is increasingly used as a protein component in the feed rations of cattle, poultry, and pigs.

Ackerbohnen in der Blüte
Faba beans in the flowering stage (Source: Landpixel)


Chocolate blotch disease (Botrytis fabae)

The infestation of the chocolate spot fungus usually begins on the older leaves of the faba bean and can be recognised by small, round, brown spots with a reddish edge. Warm and humid weather leads to a strong spread of the disease. As the disease progresses, the stems and pods of the faba bean are also affected. When the leaf spots merge, the leaves die, which impairs photosynthesis.

The Botrytis fungus is widespread. In the case of faba beans, infection usually begins at the time of flowering. The use of a suitable fungicide is a possible option for combating the disease.

Blight spot disease (Ascochyta fabae)

Blight spot disease is often confused with the early-stage spots of chocolate blotch disease. Blight spot disease can be recognised by sunken brown-reddish spots on leaves, stems and pods. Dark spore reservoirs (pycnidia) can often be seen in the centre of the spots on a grey background.

The fungus Ascochyta fabae spreads via infected seed. Control measures include the selection of a highly resistant variety and the use of cleaned seed. It is recommended to take a cultivation break of 3-4 years and to maintain a cultivation distance of at least 500 metres from fields where field beans were cultivated in the previous year. Harvesting earlier in the season can also reduce infection.

Schokoladenfleckenkrankheit (Botrytis fabae)
Chocolate blotch disease (Botrytis fabae) in the field (Source: Landpixel)
Ackerbohnenrost (Uromyces viciae-fabae)
Faba bean rust (Uromyces viciae-fabae) in the field (Quelle: Landpixel)

Faba bean rust (Uromyces viciae-fabae)

This fungus is characterised by orange-brown rust pustules surrounded by a yellow halo. When infected with the pathogen, the pustules form on the leaves, the stem and the pods. Infection occurs at warmer temperatures of over 20 degrees and high humidity, from the beginning of flowering. Rust usually occurs in field beans when the crop is in the pod development stage.

The pathogen causes damage to leaves and leads to leaf loss, which reduces photosynthesis and inhibits growth. The spores of the fungus are easily transferred to other plants by the wind. The cultivation of rust-resistant varieties and early, not-too-dense sowing are effective preventative measures.


Black bean aphid (Aphis fabae)

The black bean aphid already causes considerable damage to the crop through direct feeding. Suction damage inhibits the growth of the beans and damages the flower. The honeydew secreted also favours the growth of the chocolate spot fungus (Botrytis fabae).

In addition, the black bean aphid transmits a number of viral diseases, which can occur individually or as mixed infections. Common symptoms of virus diseases are lightened leaf veins and slightly to heavily curled leaflets.

Aphids occur primarily in the warmer months. Early sowing and rapid juvenile development mean that the bean has already outgrown the critical phase. Natural predators such as parasitic wasps, ladybirds, hoverflies and lacewings should be encouraged.

Leaf edge beetle (Sitona lineatus)

The adult leaf edge beetles migrate from winter storage (soil, grassland, other legumes) into the bean crop in spring. They feed on the leaves and leave U-shaped notches on the edge. Furthermore, there are considerable yield losses when the pests lay their eggs and the larvae of the leaf beetles feed on the roots and especially the root nodules of the plants. The leaf edge beetle is not only a pest of faba beans but also infests grain peas, lupins and other legumes.

A yield-reducing effect in field beans, peas, lupins and similar crops can be prevented by rapid juvenile development of the plants and prevention of egg laying through early insecticide application.

Blattrandkäfer (Sitona lineatus)
The leaf edge beetle (Sitona lineatus) can lead to considerable yield losses (Source: Landpixel)
Ackerbohnenkäfer (Bruchus rufimanus)
Ackerbohnenkäfer (Bruchus rufimanus) fressen sich durch die Samenschale (Quelle: Landpixel)

Faba bean weevil (Bruchus rufimanus)

The faba bean beetle can cause devastating yield losses in faba bean crops. The larvae of the beetle hatch from eggs laid on the surface of the young pods and bore into the interior of the beans, where they pupate. The adults hatch and eat their way through the seed coat, causing the typical damage pattern of pitting.

The larvae reduce the carbohydrates and proteins in the grain, which reduces the quality of the beans. If the embryo is damaged, the germination capacity of the field beans is reduced. No further damage is caused by hatching beetles during storage of the harvested crop, as they lack suitable food sources.

Chemical-synthetic plant protection has so far proven to be less effective in controlling the field bean weevil. Infestation reduction can mainly be achieved through agronomic measures, such as long cultivation breaks and deep ploughing.

Conclusion: Protect faba beans from diseases and pests by combining different measures

Crop rotation planning, in particular maintaining cultivation distances and choosing resistant varieties, reduces the spread of diseases and pests in field beans. The use of certified Z-seed also plays an important role. Close observation of the weather and the crop enables a targeted and rapid response to an incipient infestation, allowing the farmer to minimise quality and yield losses.

Ensure a vital faba bean crop with LEGUGUARD

Plant vitality is an important measure of how well a plant is able to grow, develop and resist or cope with diseases, pests and environmental stress.

LEGUGUARD seed treatment can be used to boost the vitality of faba beans in a targeted manner. Reliable germination and increased vigour (+ 6%) mean that the first phase of the vegetation period can be optimally utilised. The young plants are able to pass through the critical phase of field emergence more quickly (Disease-Escape-Effect). In addition, LEGUGUARD specifically promotes nodule formation, which means that a higher N-fixing capacity can be achieved. Together with an increased root mass (+ 20%) and surface area, resources can be utilised more efficiently - the best prerequisites for guaranteed yield stability (+ 5% additional yield)!

All values on average based on 16 field trials in the period 2020 - 2022, 3 of which were carried out by GEP-certified trial facilities, compared to the control without LEGUGUARD, depending on seed, soil and environmental factors. Status: 04/2023


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