Learn About Plant Rust Disease And Rust Treatment


By: Heather Rhoades

Plant rust is a general term that refers to a rather large family of fungi that attack plants. Frequently, when a plant is affected by rust fungi, many gardeners feel at a loss as to what to do. Rust treatment as a plant disease is startling but can be treated.

Symptoms of Plant Rust

Rust fungi are very easy to identify on the plant. The disease can be characterized by a rust color on plant leaves and stems. The rust will start out as flecks and will eventually grow into bumps. The plant rust will most likely appear on the underside of the leaves of the plant.

The good news is that there are so many kinds of rust fungi and they are so plant specific, that if you see the rust color on plant leaves of one type of plant, you will not see it appear any other types of plants in your yard.

Rust Treatment for This Plant Disease

For rust fungi, prevention is the best defense. Rust thrives in a wet environment, so do not overwater your plants. Also, make sure your plants have good air circulation inside the branches and around the plant itself. This will help it dry its leaves faster.

If plant rust does affect your plant, remove affected leaves at the first sign of rust color on plant leaves. The faster the affected leaves can be removed, the better chance your plant has for survival. Be sure to dispose of these leaves. Do not compost them.

Then treat your plant with a fungicide, such as neem oil. Continue to remove leaves and treat the plant until all signs of the plant rust are gone.

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There are many species of the rust fungus disease affecting host-specific plants and flowers, but no matter the species, gardeners can recognize this problem by observing the speckled masses that form on the surfaces of leaves.   Like the namesake, many of these pustules are rust-colored, but gardeners should also suspect rust if they see dry spots that are brown, orange, purple, red, or yellow.

Rust spots are usually tiny, scattered across plant leaves like freckles. Affected plants can have dozens of rust spots on each leaf, and it’s possible for a single leaf to have more than a hundred rust spots.


Rust Infection

One of the few upsides to having a plant that is infected with rust is that each type of rust fungus is so plant-specific that it probably can't infect plants of another species around it. Like many other fungi, rust is spread through spores that travel through the air, which is why it can appear, quite literally, out of the blue. If you do have a rust infection in the midst of a group of similar plants, however, you must get the infection under control before it can ruin the entire group. When multiple plants are infected, treatment can be difficult and typically requires frequent monitoring to fight its spread.


How to identify a rust infection?

The symptoms of a rust infection are quite easy to read. By regularly checking the plant leaves, gardeners can identify a rust infection in time and stop it from spreading. Though rust diseases affect a variety of plants, the manner in which the symptoms of this infection manifests themselves remain more or lesser similar in all plant species.

The fungus goes through different stages in its lifecycle and ultimately physically manifests itself in the form of yellow, orange, and brown powdery pustules. In case of severe infections, the colour of these blisters or pustules can change to black or purple-brown as well.

If you think rust has affected your garden or plant products, the first thing you must do is check for blister-like swellings or spots on the underside of the leaves. Most likely, these spots will be either yellow or orange in colour. Similarly, rust infections also manifest themselves in the form of white or yellow spots on the top leaves of a plant.

If you have been experiencing defoliation, a rust infection could be the main reason behind it because when a rust infection spreads, the leaves turn dry and fall down from the plant. In conclusion, keep an eye out for any blister-like appearances on the leaves of your plants.


Grow Cannas with Confidence

Canna makes a bold vertical statement with a tropical flair that is as attractive in containers as it is in the garden.

Yes, opportunistic fungi are out there waiting for that rainy spell and those tantalizingly wet leaves.

However, you can foil its attempts to colonize with best gardening practices and the scrupulous application of fungicides.

And if you’re gardening in a region with frequent summer rain and high humidity, containers that you can roll under the canopy of a patio, until the clouds break and the sun returns, may be the way to go.

Don’t let worries about rust undermine your enthusiasm! Add canna to your garden planner today.

If you are growing canna lilies you may also like to learn about growing these stunning flowers next:

© Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Product photos via Arbico Organics. Uncredited photos: Shutterstock.

About Nan Schiller

Nan Schiller is a writer with deep roots in the soil of southeastern Pennsylvania. Her background includes landscape and floral design, a BS in business from Villanova University, and a Certificate of Merit in floral design from Longwood Gardens. An advocate of organic gardening with native plants, she’s always got dirt under her nails and freckles on her nose. With wit and hopefully some wisdom, she shares what she’s learned and is always ready to dig into a new project!


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