What causes rust on my plants?
Rust is a fungus that is spread by wind, which affects a variety of different plants including garlic, onions, silverbeet, beetroot, roses and leeks.
Rust starts on the foliage of plants and spreads by leaves touching each other or by the wind blowing the spores from one plant to another. Before you know it, your whole crop or plant is affected by rust!
The most common causes of rust is moisture in the air or soil, or from planting your crops too close together, so that there is not enough airflow. Rust is a force of nature and can’t be controlled in the way some people like to think it can. If you live in a cold area, you are likely to escape this dreaded fungus. However, a mild winter will enable spores to remain rather than being kept under control by the cold.
What damage does rust cause on my plants?
Rust can destroy your whole crop if it gets a bit of momentum. When I see the first signs of rust, I am ruthlessly quick to pull the plant out and salvage what I can to eat. I then burn the rest. If left in the ground, this disease will spread from one plant to the other.
Occasionally, even this fails and the rust will still infect your whole garlic crop; while your onions stay safe – another mystery of nature! Rust is specific to its own crop so garlic rust won’t spread to your roses and vice versa.
If your crop is nearly ready for harvesting, you can remove most of the leaves to try and help the disease slow down. Remember to wash your hands and gloves afterwards just to be doubly sure not to spread the bacteria.
How can I prevent rust from developing on my plants?
There is NO fail-safe way to successfully control rust, however there are some actions you can take to minimise the risk of rust.
Water in the morning and not at night, as the water will sit there all night until the heat of the day, which will give the rust spores time to take hold.
Water at the base of the plant and not overhead. My recommendation would be no overhead watering for any plants during spring/summer.
Give your plants room to breathe and try not to overcrowd them by planting too close. Good airflow is the key.
Rotate your crops, or resign yourself that some things you just can’t grow in your area, climate or soil type – humidity and clay soils are definitely high on this list (sorry Waiheke!). If you have space, I strongly urge you to wait seven years before you put the same plant in the infected spot.
Sterilise your tools to prevent spreading the disease from one plant to another. Also wash your hands or gloves after dealing with plants contaminated with rust.
Good luck and long may your garden continue without rust!