What is Leek Rust?
Brownish orange streaks or spots on the leaves of leeks and other alliums is known as Leek Rust. It is a fungus that develops on the leaves of any alliums – leeks, onions, garlic – and it’s not uncommon, especially in autumn when damper weather arrives.
If your plants are affected
Once you see signs of leek rust on your leeks, don’t despair. You can still harvest your leeks and cook them – just peel off the affected leaves before you wash and chop them. If they’re not really ready to harvest yet, you can remove diseased leaves (being sure not to leave them lying on the soil) and give the plants a good watering. Try not to get water on the foliage, just water them at the base. With luck they will continue to grow without too much further infection.
One important thing to note is that if you leave any infected foliage lying on the soil, then other leeks are highly likely to catch it. You can compost them, but do so well away from your bed of leeks. Alternatively, pop them on the bonfire next week!
How to prevent Leek Rust
To avoid it in the future, we’d recommend 3 things:
- Avoid growing leeks in nitrogen-rich soil. Nitrogen can soften the leaves and make the plants more susceptible. If you use manure in the garden, you may find that your soil is quite high in nitrogen. Instead, try using a multi-purpose compost where you are planning on growing leeks.
- Give plants a little more space. Planting too closely together restricts air movement in and around the plants, and by increasing this you will minimise the risk of leek rust taking hold of your plants.
- Try to keep soil moisture consistent. Long dry spells followed by heavy rainfall don’t help when it comes to leek rust. Try to keep things even as much as possible (obviously this year it has been very dry, so a little more challenging!)