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How to Identify and Control Rust Plant Disease

Fungal rust disease infiltrates these spinach leaves.

Photo Credit
Rust photo by Howard F. Schwartz via Wikimedia Commons

You Can Prevent Rust Plant Disease!

Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

What is rust plant disease? This fungal disease looks like you have rust on your plants and affects a wide range of woody and herbaceous flowers and vegetables. Even though it rarely kills plants, it reduces their 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 by wind or water, which is why rust disease often spreads after watering. Wet surfaces are also needed to cause infections.

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Identification

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

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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.

Plant Disease
About The Author
Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the website companion of The Old Farmer's Almanac. She covers gardening, plants, pest control, soil composition, seasonal and moon c...
Read More from Catherine Boeckmann

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Comments

<a title="View user profile." href="/author/editors">The Editors</a> Fri, 11/14/2014 - 15:32

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.

http://www.usna.usda.gov/Gardens/faqs/hydrangeafaq2.html

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

http://www.almanac.com/plant/hydrangea

 <span>Carole Clark</span> Thu, 08/07/2014 - 14:40
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?
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 08/08/2014 - 10:58

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.

 <span>Grannyxfive</span> Tue, 05/20/2014 - 13:50
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
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 05/21/2014 - 10:21

 

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.

 <span>Ron Keller</span> Tue, 11/19/2013 - 12:38
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 liquid...is 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, Ron
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 11/20/2013 - 14:33

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.

 

 <span>Roberto</span> Sun, 04/01/2012 - 20:57
What about on your lawn? I have rust on my lawn does anybody have any ideas.
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 04/04/2012 - 10:30
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