Remove and bin the worst-affected leaves. On a lawn, feed and mow regularly — lawn rust is largely a symptom of underfed, slow-growing grass.

Will rust spread to my other plants?

Yes. Rust spreads, so deal with affected material promptly and keep it out of the compost.

Rust

Q: What causes rust?

Rust is fungal disease. Rust is easy to identify because the spores genuinely look and behave like rust — an orange powder that transfers to whatever touches it. On a lawn it turns shoes orange when you walk across. It weakens plants over time but is rarely fatal.

Treatable

Fungal disease · spreads to other plants

Rust is easy to identify because the spores genuinely look and behave like rust — an orange powder that transfers to whatever touches it. On a lawn it turns shoes orange when you walk across. It weakens plants over time but is rarely fatal.

What it looks like

Small raised pustules of orange, rusty-red or brown powder, almost always on the underside of the leaf, with a corresponding yellow spot on top. The powder comes off on your fingers and on clothing.

How to confirm it

Orange powder that rubs off onto a finger or a white tissue.
Raised pustules on the leaf underside, yellow flecks above.
On lawns, shoes and mower wheels turn orange.
Worst in humid weather on plants that are short of nitrogen.

What to do

1Remove and bin the worst-affected leaves.
2On a lawn, feed and mow regularly — lawn rust is largely a symptom of underfed, slow-growing grass.
3Water at the base and improve air circulation.

What it gets confused with

One observation settles each of these.

Spider mites →

Mites produce fine stippling and webbing, not raised orange pustules, and the specks move under a lens.

Cedar-apple rust

On apples, cedar-apple rust makes bright orange spots on the upper leaf surface with fringed tube-like structures beneath.

Preventing it next time

Avoid overhead watering, especially late in the day.
Keep nitrogen adequate; rust exploits weak growth.
Choose resistant bean and rose varieties.

Plants affected

Beans Roses Apple & Pear Lawn & Grass

Check these two things first

Push a finger into the soil, two knuckles deep. Wet soil plus a wilting plant means too much water, not too little — and it is the commonest reason a plant is dying. Dry soil plus crisp leaves means the opposite. The leaves look nearly identical either way, so the soil is what tells you.
Turn a damaged leaf over. Half of all diagnoses live on the underside: fuzz means downy mildew, fine webbing means spider mites, clusters of insects mean aphids. Nothing on the top of a leaf is as informative.

Most garden problems are cosmetic and resolve without treatment. Reach for a spray last, not first.

Not sure it is rust? Run the diagnostic key →