There are hundreds of types of fungi that cause ‘rust’ on plants but each type has a limited number of host plants so that your whole garden is not likely to be overrun by rust.
Rust can occur in various seasons but it does need moisture to grow. It typically causes yellow or brown markings on upper surface of leaves, and small yellow or brown powdery growths on the underside of leaves. The powdery substance consists of fungal spores that can be blown about by wind, infecting other plants that are susceptible to that type of rust fungus.
Below, on the left, are pictures of rust on the underside if a frangipani leaf and typical signs of rust on grasses. Some leaf markings can be confused with fungal diseases. On the right are pictures of hail damage on a cycad and spores on the underside of a fern frond – which is how ferns reproduce.
Basically, rust diseases are a sign of malnutrition that produces an unsuitable pH on the leaf surface. Plants, like humans and animals, are more prone to diseases when they have a poor diet, and rust diseases can be avoided by keeping plants growing vigorously – but this is not always possible in extreme weather conditions. Sulphur or copper are the usual treatments for rust. Both of these are nutritional elements that can be supplied by various fertilisers, including seaweed extracts. Seaweed also contains plenty of potassium that strengthens cell walls, sulphur, and trace elements (including copper) that boost plants’ immune systems.
For mild cases of rust, remove damaged parts of the affected plant and burn these, or dispose of them in a sealed plastic bag. Don’t ever compost them, as the spores may not be killed. Then give the plant a foliar feed of seaweed extract tea and water some into the ground over the root area. Improve your fertilising program using a complete organic fertiliser.
For deciduous plants, rake up and dispose of dropped leaves to avoid reinfecting the plant. Apply the seaweed tea at bud swell.
For more severe cases, after removing damaged foliage, plants can be dusted with elemental sulphur (flowers of sulphur. However, as the spores are under leaves and the dust can be difficult to apply, affected plants can be sprayed with wettable sulphur in cool weather only, as sulphur will damage plants when temperatures are over 24 degrees Celcius. Be aware too, that sulphur will also kill pest predators. If these are present on affected plants, apply chamomile tea (one tea bag to 500 ml water) instead.
Moon Planting Calendar 2019Our 2019 moon planting calendar for Australia and New Zealand is now available for purchase.
GARDEN ADVICEIf you have a gardening problem, I can provide advice on Aussie Organic Gardening. (PLEASE INCLUDE YOUR LOCATION as climates and soils vary greatly in our wide, brown land.) E-mail me at: firstname.lastname@example.org
- Around the farm… (56)
- Frogs (4)
- Chain saw carpentry (4)
- Chooks (1)
- Climate Zones (2)
- Fruits and Vegetables (124)
- Garden projects (13)
- Healthy soil (44)
- Herbs (28)
- Moon Planting diary (26)
- Moon planting explained (10)
- Ornamentals (61)
- Pest-free Gardening (58)
- Recipes (2)
- Saving seed (6)
- Seed suppliers (3)
- Uncategorized (29)
- Weeding between the lines (10)
- Around the farm… (56)
- What to grow in January 2019 January 4, 2019
- Tis the season … December 3, 2018
- What to grow in December 2018 December 1, 2018
- Moon planting calendar for 2019 November 30, 2018
- 2019 Moon Planting Calendar November 30, 2018
- What to grow in November 2018 October 30, 2018
- What to grow in October 2018 October 1, 2018
- Banksia rose September 16, 2018
- What to grow in September 2018 September 3, 2018
Blogs and other sites