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Rust, techniques and treatments to avoid it

Small dots of yellow and a few brown blotches dot the top of a rose leaf covered in rust.

Even though the number of fungal diseases called “rust” is very high, they almost always share the same symptom: brown-orange blisters appear on the underside of leaves with yellow stains on the topside.

Here is the right treatment for this disease.

What factors lead to the appearance and spread of rust?

This disease most often appears during moist weather or excessive watering on leaves.

Wind can spread it to other plants in the garden.

When does rust appear and spread?

From the beginning of spring till the end of summer.

Which plants are vulnerable to rust?

Rose rust, underside of leafThere are a great many species that can develop this disease.

Rose trees are very often contaminated with rust, but many flowers, fruit trees, trees, shrubs and vegetables can be impacted as well.

Consequences of rust

What looks like a hairy orange caterpillar is actually rust spreading along the veins of a curled-up rose tree leaf.In most cases, rust does not fatally endanger the life of the plant.

In the very worst case, all the leaves are lost.

What is especially problematic is contagion, the spread of the disease to other leaves on other plants.

It results in rose shrubs not looking very nice in August.

Although there are many different types of rust, the once most commonly encountered has the latin name Phragmidium mucronatum.

How to treat against rust

Effective treatment products are often sold under the label “rose tree disease” and can be used to treat other plants as well.

  • These are usually fungicides that can be used both to cure and to prevent rust.
  • As soon as the first symptoms appear, you must quickly remove all infected leaves and burn them.
  • Use a disinfected secateur or shears, and disinfect them again between each cut.

Here are a few natural fungicides made from fermented tea, they’re easy to make yourself:

Other diseases and treatments

Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Rust on rose tree leaves by Jerzy Opiola under © CC BY-SA 4.0
Orange spots under rose tree leaf by Jerzy Opiola under © CC BY-SA 4.0
Orange powder puff on rose leaf by Teresa Clements ★ under © CC BY-SA 3.0

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