Appeared in Alsace in 2003, the leek leafminer has continued to progress westward to the point of becoming one of the leek's most formidable enemies.
If there is one parasite that undermines leek crops, it's the leek leafminer! If it is still difficult to eradicate it, then it remains to prevent its appearance ...
A small greyish fly 3 mm long and known as Phytomyza gymnostoma, the leafminer attacks leeks twice a year, in spring and fall.
If the damage is mainly specific to leeks, the leafminer can also attack the chive, at theshallot et al'onion.
- To read : all you need to know about growing leeks
Development conditions of the leek leafminer
To date, no study has succeeded in formally determining the development conditions of the leek leafminer.
Several parameters can be taken into account, such as temperature, humidity level or the quality of the soil, but none can be considered as obvious or determining.
Leek leafminer attack period
There is a certainty today, that the leafminer has 2 flight periods in the year, in spring and in fall.
We thus see attacks in April, May and June then at the end of summer, from August to November.
The larva is yellow in color, it then becomes a reddish-brown pupa before becoming an adult fly.
Leek leafminer life cycle
- The male impregnates the female who lays eggs after having caused feeding stings on the leaves. These bites cause small white dots on the top of the leaves.
- Once these bites are carried out on the top of the leaves, the female flies lay their eggs there, which will become yellow larvae.
- These larvae will feed on the leek plants by burrowing in them to the base.
- Brown-red pupae then form at the end of the galleries made by the larvae.
- The pupae will remain on the leek plant all summer until they become adult flies. these same flies will fly in late summer and fall for a new fertilization period.
- Fall pupae manage to spend the winter in leeks and resume their cycle in the spring.
- As you can see, if you don't pull out the infested plants, the leek leafminer can start its cycle of fertilization and egg laying again for a long time.
Treatment and control of leek miner
Today there is no cure for the leek leafminer.
On the other hand, it is possible to prevent its occurrence by protecting crops from leeks.
Anti leek leafminer net:
- The priority and the most effective means of control is the anti-insect veil with a mesh of 5 mm maximum, ideally 850 µm or microns.
- Drive in the hoops so that the fillet is not in contact with the leeks
- Make sure there is no space, even at ground level, of more than 5mm.
- You can remove the net after any risk of leafminer attack.
Destroy attacked leek plants:
- Prevention also involves destroying all infested plants.
- Do not put in compost because the pupae could reappear elsewhere and make your compost unusable.
- Make sure you have everything pulled out, as even the smallest trace of leafminer left behind may be enough to bring back the fly.
Insecticide and repellents against the leek leafminer:
To date, there are no effective insecticides against leafminers, whether organic or systemic insecticides.
But some fragrant plants seem to have a positive effect as a repellent against the leek leafminer.
- It is then important to plant the leeks in small groups in the middle of the repellent plants.
- We find as a plant, mint, lemon balm or rue.
- To read : all you need to know about leek cultivation
- To discover : all the sheets and recipes on leek