Leek is a robust plant that requires little care. However, some diseases and pests cause problems for leeks. The plants must be carefully observed so that possible damage is noticed in good time.
What pests and diseases can attack leeks?
The most common leek diseases and pests are leek rust, downy mildew, yellow streak virus, leek moth, leek leaf miner and thrips. Preventative measures include regular inspections, planting resistant varieties and placing tight-meshed nets over the bed.
Pests and diseases of leeks
Despite the best care, diseases and pests cannot always be prevented. Regularly checking the leaves and stalks of the leek after sowing is therefore the best prevention so that the infestation cannot spread further. The most important leek diseases and pests are:
- Leek rust
- Downy mildew
- Yellow stripe virus
- Leek moth and leek leaf miner fly
- Thrips
Leek rust
Leek rust is the most common disease of leeks. It can be recognized by the strong orange rust pustules that appear on the leaves. If leek rust occurs, the only option is to dispose of all affected plants.
Downy mildew
A whitish coating on the tops of the leaves and brown undersides of the leaves are the signs of downy mildew. It mainly occurs in very humid weather. Cut off all affected parts of the plant and treat the remaining leek plants with a manure made from field horsetail.
Yellow stripe virus
Yellowish stripes on leek leaves are caused by the yellow stripe virus. If the virus has appeared, the plant must be disposed of. For prevention, select resistant varieties to plant leeks.
Leek moth and leek leaf miner fly
If burrows and black dots appear in the leek stalks, leek moths and leek leaf miners were at work. The pests lay their eggs in the leek. After hatching, the larvae eat their way through the stalks and reduce the leek harvest. Stretch a close-meshed net over the bed as soon as the first leek plants have sprouted. This prevents the pests from laying eggs.
Thrips
White-grey speckled spots on the leek indicate thrips. These pests are very small and can usually only be recognized when the plant can no longer be saved. Once the spots are visible, you can try rinsing the plant with lukewarm water. However, any help usually comes too late.
Tips & Tricks
Leek plants affected by diseases and pests must never be disposed of in the compost. Otherwise the pathogens will continue to spread. Throw the rods in the trash can or burn them.
