Pests such as bean flies and bean aphids endanger the growth of bean plants. Diseases such as bean mosaic virus, fat spot disease, focal spot disease and bean rust can even lead to the death of entire plants and thus to crop loss and crop failure. That doesn't have to be the case!
What pests and diseases can affect beans?
Beans can be attacked by pests such as bean flies, bean aphids and snails, as well as diseases such as bean mosaic virus, fat spot, burn spot and bean rust. Preventative measures and targeted control help to protect plants and prevent crop losses.
Bean mosaic virus
Yellowish, mosaic-like spots on the leaves indicate the viral disease. Leaves yellow and die, in the worst case the entire plant dies.
The cause of the infestation is already infected seeds. Aphids transmit the virus to neighboring plants and warmth promotes the spread. Infected plants can be disposed of in the compost.
Prevention:
- buy certified, virus-tested seeds
- growing resistant varieties
fat spot disease
It mainly affects bush and runner beans and is caused by bacteria. Small yellow to light green, oily spots appear on the leaves. The leaves deform and die, often before flowering. Pods, stems and seeds can also be affected.
The cause is infected seeds, infected plant remains and spread by snails.
Combat:
- Spraying with horsetail broth
- burn infected plants
Focal spot disease
This fungal disease causes leaves, stems and pods to be covered in dark, burnt-looking spots. If the infestation is severe, the leaves will fall off. If the fungus attacks the seedlings, young plants are already at risk of dying. Bush beans are particularly at risk.
Combat:
- burn infected plants
- Don’t grow beans on the same bed for five years
bean rust
The fungal disease occurs in damp weather and can be recognized by white to rusty brown pustules on the underside of leaves and on pods. The cause is unnecessary nitrogen fertilization, a warm, humid climate and the close proximity of plants.
Combat:
- destroy infected plants
- Don't grow beans in this place for five years
Black bean aphid
The approx. 2 mm large black bean aphid lives on the undersides of leaves, attacks the tips of shoots and causes them to become crippled. The black bean aphid overwinters in the soil or on host plants such as the viburnum and attacks the plant as early as May.
Combat:
- cut off affected shoot tips
- Combat with nettle infusion, neem, Neudosan aphid free
Bean fly
Holes in the bean seeds and feeding spots on cotyledons and root necks indicate infestation by the 4 - 5 mm large gray bean fly. It lays its eggs in bean seeds and seedlings from April to May, and its larvae eat their way through the cotyledons.
Prevention:
- Pre-germinate seeds
- do not sow on beds where fresh manure has been applied
- Protect beans with cultural protection net
- simultaneous sowing of savory, which is unpopular with bean flies
Snails
Seedlings and young bean plants in particular are a treat for snails. To protect the plants, slug pellets should be scattered. It is also helpful to move them forward, as the growth advantage makes the plants less vulnerable.
Tips & Tricks
Picking beans in dry weather reduces the risk of infection for neighboring plants. When picking, pressure points and damage can occur, which serve as an entry point for spores and bacteria. Their proliferation would be encouraged by wet weather.
