How To Identify, Control & Prevent Rust Fungus

Have you noticed reddish, rusty-looking spots on your plant’s leaves? Then, act quickly because it could be rust fungus, and this nasty infection can wreak havoc in even the most fastidiously clean and tidy garden. 

Rust fungus is one of the most commonly found plant diseases in the UK, affecting a wide range of plant life. And what’s more, it’s super-challenging to remove. 

But never fear: this article explains how to identify, control, and prevent rust fungus from ruining the look of your beloved garden. 

Ready? Let’s get started.

Rust fungus at a glance

Pucciniales, aka rust fungus, belongs to the Basiodiomycota fungi family, comprising 14 principal varieties and 7000 sub-species. Which — let’s face it — suggests that rust fungus is an adaptable and tenacious life-form. 

However:

Despite the vast variety of rust fungi that could infect your garden plants, the measures to combat them don’t differ significantly. 

How do rust fungi affect the plant?

Regardless of the variety, rust fungus sits on plant leaves, depriving it of essential nutrients. Some varieties are host-specific and only infect certain plant species, while others are more adaptable. 

Ultimately, anything that steals a plant’s nutrients tends to prosper while the poor plant suffers. 

Indeed, rust fungus infection tends to result in poor growth, leaf discolouration and loss, rotting fruit, and pustules, which can eventually kill the plant if left untreated. 

How to recognise rust fungus

You’ll find evidence of a rust fungus infection mainly on a plant’s leaves. And while symptoms vary from plant to plant, they’re typically characterised by yellow/orange spots on the upper side of leaves, with brown or orange spore deposits underneath the leaves. 

Infected leaves will turn yellow and wilt and will eventually shed. 

And on closer inspection, you may see tiny white mycelium dots on the leaves. 

Preferred host plants of rust fungus

While affecting a whole range of crops and ornamental plants, this common infection is most prevalently found on:

• Roses
• Mallow
• Apple and pear trees
• Chrysanthemums
• Peppermint
• Green beans
• Asparagus
• Beech
• Spruce
• Oak

Fighting rust fungi

Tackling rust infection requires a combination of preventative measures and targeted treatments. 

First, cut back the infected plant limbs to healthy foliage, which will help the plant recover over time. However, if the plant is terminally infected, remove it from your garden altogether (and don’t compost it!). 

Pluck away infected leaves as soon as you spot them, and sweep away fallen leaves immediately in the autumn, as they can encourage mould around your garden. 

Place uninfected fallen leaves in your compost, but never compost affected plant parts. 

Once you’ve removed the affected plant parts, treat the surrounding plants with an appropriate fungicide (read on for planet-friendly home remedies). This will help contain the spread of infection. 

Fighting rust fungi with home remedies

You can buy chemical fungicides from your local garden centre, but we always recommend environmentally friendly fungicides:

Baking soda

This tried-and-tested treatment is simple to make at home. 

Simply mix 1 teaspoon of baking soda with 1 litre of water, then thoroughly spray affected and vulnerable plants. Repeat the application every couple of weeks to maintain control over rust fungus. 

Milkshake

Well, it’s not milkshake as we know it! But a solution of milk and water can be a particularly effective home remedy. 

Mix one part milk with two parts water, then pour the solution into a spray bottle and spray affected and nearby plants. 

Repeat every couple of weeks to maintain protection. 

How to prevent rust fungus

The best way to prevent rust fungi in your garden is to choose rust-resistant varieties. There have been enormous strides in plant breeding, especially with roses, so consult your friendly garden centre advisor regarding rust-resistant varieties. 

Also, avoid cramming plants into your flowerbeds because crowded beds are susceptible to rust fungus. Allow good air circulation between individual plants. 

Finally, keep your plants well watered and feed them regularly with a high-quality fertiliser. This helps keep your plants strong and disease-resistant. 

Should I just let rust fungus run its course?

This nasty fungus spreads quickly, so never ignore it. In the worst cases, infection can take over the entire garden, so never delay. 

FAQs

Ready to protect your garden?

Rust fungus causes significant garden damage, but you can combat the infection with proper prevention and control. 

We hope this article was helpful, but if you have any questions, don’t hesitate to get in touch. Or, if you think you might have another garden infection, check out our Pests and Diseases category in our Help & Advice section.

Happy gardening!

Louis Hooft

Founder & Lawn expert

Introducing Louis Hooft, the founder of MOOWY and your reliable expert. With a profound love for stunning lawns and extensive experience in garden maintenance, Louis is here to assist garden enthusiasts in achieving a greener and livelier outdoors than ever before. Count on Louis for invaluable tips, clever tricks, and top-notch products to make your garden flourish!