What is Rust
Rust is a fungal disease that is easily identified by the many orange, brown or reddish pustules on leaves or stems, which break open and release masses of spores. Rust is a common disease of a wide range of ornamental plants such as calendulas, roses, snapdragons, geraniums and gerberas, as well as vegetables like beans and tomatoes. Rust can also attack turf and has become a serious disease of Frangipani, willow and poplar trees. Different Rust fungi are quite specific in the host plants they affect. For example, Rust on Geraniums won't spread to other plants.
Symptoms of Rust
Rust fungus grows within the leaf. Early symptoms of infected plants include orange or yellow spots on the upper surface of leaves, followed by brown or orange pustules on the underside of infected leaves or along stems. Rust can also cause growth to distort or reduce, or cankers or galls to form. In severe cases, plants can lose all their leaves.
Plants Impacted by Rust
- Calendulas
- Carnations
- Roses
- Snapdragons
- Geraniums
- Gerberas
- Hollyhocks
- Climbing and Dwarf Beans
- Broad Beans
- Tomatoes
- Stone fruit (peaches, nectarines, plums, nectarines, apricots) and almonds
- Grape vines
- Lawn
What Are the Different Types of Rust Disease?
There are around 7000 different species of Rusts, from 168 genera. The most common genus of Rust is Puccinia and includes Rusts that affect cereal crops like wheat and barley. Rusts that affect garden plants include Rose Rust (Phragmidium tuberculatum), Bean Rust (Uromyces appendiculatus) and white Rust (Albugo tragopogonis). Rust that affects Frangipani is Colesporium plumeriae and Myrtle Rust (Uredo rangelii) affects Australian native plants like Bottlebrush, Lilly Pillies and Eucalypts.
What Weather Conditions Promote Rust?
Conditions that promote Rust infections are warm humid weather (15 to 24 degrees C) and prolonged wet foliage. Rust spores can remain dormant on plants during dry weather and spread via wind, rain and watering.
What's the Best Treatment for Rust?
Depending on the plant that is affected, there are different options for controlling Rust.
Yates Rose Gun: ready to use spray that's ideal for controlling Rust infections on Roses and other ornamental plants.
Yates Rose Shield Concentrate: a concentrate that's ideal for controlling Rust on larger numbers of Roses and ornamental plants.
Yates Lime Sulfur: suitable for use on Roses & ornamentals, as well as stone fruit, pome fruit, and tomatoes and other vegetables.
Yates Liquid Copper Fungicide: a broad-spectrum fungicide that controls Rust on Beans and Beetroot.
Currently there are no home garden products registered for controlling Myrtle Rust. If Myrtle Rust is detected on plants and shrubs, carefully remove affected leaves and stems and dispose of them in the rubbish (not the compost). This helps to reduce the spread of the infection. For trees affected by Myrtle Rust, an arborist consultation is recommended, as they have access to commercial Myrtle Rust control products.
How to Help Prevent Rust
- Avoid overhead watering. Wet foliage creates ideal conditions for the Rust spores to germinate and develop.
- Water plants in the morning (rather than later in the day), so plant foliage can dry off more rapidly.
- Grow Rust susceptible plants in areas with good air circulation. This helps to reduce the amount of time leaves stay wet.
- Monitor plants regularly for early signs of Rust infection, particularly during damp conditions.
- Practice good garden hygiene by cleaning up and disposing of any fallen Rust infected leaves.
- Control garden weeds, as they can harbour plant diseases like Rust.
- Keep plants healthy and well-fed by regularly using fertilisers like Yates Thrive and Yates Dynamic Lifter. Healthy plants are more resistant to disease infection.
- Spray with a suitable fungicide at the earliest sign of infection and repeat application as per label instructions.