Rust Plant Disease

How to Identify and Control Rust Plant Disease

Rust on Spinach by Howard F. Schwartz via Wikimedia Commons

Fungal rust disease infiltrates these spinach leaves.

Rust photo by Howard F. Schwartz via Wikimedia Commons

What is rust plant disease? This fungal disease affects a wide range of woody and herbaceous plants. Even though it rarely kills plants, it reduces a plant’s health, vigor, and flower production.

What Causes Rust?

Rust disease is caused by a fungal parasite that needs living plants to survive. Rust diseases occur most often in mild, moist conditions. Rust is spread by spores that are transferred from infected plants to healthy plants. These spores can be transferred either by the wind or by water, which is why rust disease often spreads after watering. Wet surfaces are also needed to cause infections.


    How to Identify Rust Damage

    Rust diseases come in different varieties and can affect a wide range of plants. People often struggle with rust on their roses. It is easy to remember the defining characteristics of this fungus, as they match its name. Rust plant disease will look similar to the rust that appears on that old bicycle in the shed.

    • Look for yellow or white spots forming on the upper leaves of a plant.
    • Look for reddish to orange blister-like swellings called pustules on the undersides of leaves.
    • Orange or yellow spots or streaks appear on the undersides of the leaves.
    • Within these spots that form are spores.
    • Usually leaf distortion and defoliation occur.


    Photo Credit: Bruce Watt, University of Maine. Small pustules appear on the undersides, and sometimes the tops, of leaves when a plant is infected with rust.

    Control and Prevention

    How to Control Rust Fungi

    Unfortunately, there is no easy treatment for rust. Try these tips:

    • Remove all infected parts and destroy them. For bramble fruits, remove and destroy all the infected plants and replant the area with resistant varieties.
    • Clean away all debris in between plants to prevent rust from spreading.
    • Avoid splashing water onto the leaves, as this can help spread rust.

    Rust Prevention

    • Dust your plants with sulfur early in the season to prevent infection or to keep mild infections from spreading.
    • Space your plants properly to encourage good air circulation.
    • Avoid wetting the leaves when watering plants.
    • There are many effective rust fungicides you can try. Ask your local nursery for which products you should use.


    Reader Comments

    Leave a Comment


    I have some of the same questions that were already asked, has anyone answered them? I don't see any answers.

    I got a solution but not sure.

    I had some useful plants at the corner of my greenhouse and I found rust appearing on the leaves. These are really unstoppable and damaged almost all leaves within 2 months. New leaves also shown some sign of new rust. Later, as the plants are at the corner of my greenhouse some leaves grown outside the greenhouse and surprisingly they are healthy. I moved all the plants to sun, removed the damaged leaves and later 1 month all are with new rust-free

    Mallow rust

    I've been trying to find on Google phrased Various different ways..
    Is Mallow rust (or any of these rusts) safe to consume? I just learnt a neat Mallow recipe I wanted to try but they've gotten rusty the past couple weeks


    I have 4 plants and they all look like they are burning up..all the leaves have dark brown edges that eventually take over the whole leaf..I spray with a fungicide about every 2 weeks but nothing seems to be working..any advice would be much appreciated.


    I have 2 grape vines and they already have like rust spots on the leaves and they are curling up. The grapes are dying as well. The canes look really dry and a few of the little branches I have snapped off , they were dead. Somebody help. I live in New Bern,NC


    How to clear the flower leaf RUST FUNGI...


    Should the soil be replaced in the planters that had rust?

    Rust on my pepper plants

    We have had very wet weather lately in Maryland and my pepper plants have rust spots. The first flowers are just beginning to appear. I have removed all leaves that show signs of rust - the younger leaves seem fine at the moment.. There are some black marks on the stem at the joints. Some nearby tomato plants have some leaf distortion but no rust spots. Should I remove the pepper plants, spray with a fungicide or wait and see what happens?

    rust relief

    The Editors's picture

    Pls see our advice above: there is no easy solution. Are your plants well spaced apart? A small matter at this stage, perhaps. But as for the fungicide…maybe try dusting with sulfur instead (as noted above). “Wait and see” may be a disappointment. You might feel better about trying something. Again, see above. Hope it works!


    My white hydrangea blooms have turned brown. Leaves are healthy, when new bloom
    appears, the white turns brown and die. I have about eight brown blooms now.

    Hi, newly planted Hydranger

    Hi, newly planted Hydranger was doing well for a couple of weeks but has now suddenly wilted with black marks on all the stems at the bend points. It doesn't look under watered, is it possible to overwater a hydrangea??
    Thank you!

    Black marks on your hydrangea

    The Editors's picture

    Black marks on your hydrangea sound like a fungal infection. It's been wet or humid or you're getting water on the plant's leaves. First, get rid of any fallen leaves. Then make sure your plant has good airflow and isn't crowded. Only water at the soil level when the soil is dry 3 to 4 inches down (poke your finger in the soil to check). When it's dry, water deeply enough that you end up watering about twice a week. Also, make sure the soil drains well and the plant's "legs" aren't wet. If this continues, you may need a fungicide spray.

    my Canna Lily leaves, turned

    my Canna Lily leaves, turned beige after one month in my pots. Just cut off the leaves I'm told.

    I have several hydrangeas

    I have several hydrangeas that were planted by the previous home owners. I live in NC. In late August when moved in, all the blooms were dead and dried and most of the leaves had rust spots. It is now November and the plants are developing nice green new growth at the end of the branches. However, almost all of the old leaves have many rust spots and are pale green. I would love to prune the plants way back to remove all the rust and start new healthy growth. Can I do this? When? How short? Will they bloom next year? Is there anything I should do to kill and avoid further rust? Thank you so much for your advice.

    Hi Deb, Please go to the page

    The Editors's picture

    Hi Deb,
    Please go to the page below and scroll down to see some pictures of "rust" on hydragea leaves and some advice on how to take care of it.
    Depending on what type of hydrangea you have you can prune in the fall or in the spring. If you don't know the variety and prune now you may not get any blooms next summer.
    For pruning advice got to our hydrangea page at

    Just planted a Hortensia

    Just planted a Hortensia hydrangea early this summer. Had only 1 bloom on it, but a few of the leaves started to turn brown on the edges. Now all the leaves are doing this, brown w/tiny white spots. What can I do?

    Hi, Carole: This could be any

    The Editors's picture

    Hi, Carole: This could be any number of things, or even a combination, but it sounds like powdery mildew is a good place to start. Go to "Gardening" above and click on "Pests and Diseases Library." Find "Powdery Mildew" and follow the instructions there. While you're there, check out other diseases and see if any of the photos more closely resemble what is happening to your plant. In general, though, clean off or remove the bad leaves, make sure your plant has good air circulation, don't overwater (although brown edges without the white spots might mean underwatering), and put down a thin layer of mulch below the plant to cover up any residual nasties that may be lying in the soil and potentially become harmfully airborne again.

    Last year was given 5 plants

    Last year was given 5 plants from 5 different sources. I noticed spots so I removed all the leaves. They are filling out nicely now again. However 3 days ago noticed every leaf on both stalks on 1 plant have all drooped including new growth. One other plant has some drooping leaves as well but the rest are fine. I water in the evenings & have sprayed the plants with soap/H20 solution 2 times as I'm seeing spots again. Suggestions? Tampa, FL

      Rust thrives in wet

    The Editors's picture

    Rust thrives in wet conditions, so do not overwater your plants. Also, make sure that you have good air circulation around the plants.
    We suggest that you spray the plants with organic neem oil, found in most garden centers.

    I have a plumeria plant and I

    I have a plumeria plant and I live in Orlando, Fl. I am loosing my leaves to rust. In the article above, It states that I should remove the leaves and destroy them. I am new to caring for plants so forgive my dumb questions. Do I just strip the plant of all it's leaves? It's a small plant, it has about 15 leaves on it. Anytime I pull a leaf off, it oozes a milky white that normal? Will stripping off all the leaves kill the plant or will it grow new ones fast? My apologies for my ignorance. Thanks for the help,


    Hi Ron, Carefully remove the

    The Editors's picture

    Hi Ron,
    Carefully remove the infected leaves and throw them out with the trash. Instead of pulling the leaves off use clippers or scissors. Rust is common in the fall months. Normally the plant will go dormant and  will drop all its leaves for several weeks in the winter. When new leaves emerge in the spring the rust is usually gone.

    What about on your lawn? I

    What about on your lawn? I have rust on my lawn does anybody have any ideas.

    Hi, Roberto, One of the main

    The Editors's picture

    Hi, Roberto, One of the main reasons that rust develops is a low amount of nitrogen in the soil. Fertilize with a good organic fertilizer high in nitrogen to strengthen the lawn. Mowing the grass a little shorter and removing the clippings, plus watering in the morning will also help. --TOFA


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