Rust (various)
Puccinia spp.; Uromyces spp.
Orange, brown or black powdery pustules on leaf undersides. Common on beans, garlic, leeks and silverbeet.
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Identify from a photoBackground
Rust diseases are caused by specialised fungi in the order Pucciniales. Each is host-specific, so bean rust will not infect garlic. They thrive in mild humid conditions. Infections reduce photosynthesis and can severely weaken plants if left unchecked.
How to identify
- Small orange, brown, yellow or dark pustules (sori) on leaf undersides, sometimes on upper surface
- Older lesions dark brown/black spore stages
- Leaves yellow and drop prematurely
- Bean rust: brick-red pustules on pod and leaves
Life cycle
Spores wind-borne, germinate in free water or high humidity, infect in 4-8 hours. New pustules in 7-14 days. Some rusts need alternate hosts to complete their life cycle.
Weather triggers
- Temperature: 10-28°C
- Humidity: >80%
- Rainfall trigger: >5mm
- Mild humid weather with overnight leaf wetness. Hot dry spells slow disease.
Peak season (southern hemisphere)
Red = active season · Dark red outlined = this month
Affected vegetables & crops
Click any crop to see current prices and growing info.
Climate zones at risk
Organic & low-impact control
- Remove and bag affected leaves at first sign
- Sulphur spray (not during heat)
- Copper-based fungicides as protectant
- Increase airflow
Chemical control
- Myclobutanil and tebuconazole systemic fungicides registered for commercial use; check current home garden options
Always read product labels. Registrations change.
Prevention
- Choose resistant cultivars where available
- Avoid overhead watering in late afternoon
- Rotate beds
- Remove crop residue at end of season
Companion planting
No strong companion effect.
Biosecurity
Some rusts are biosecurity-relevant (e.g. myrtle rust on ornamentals). Vegetable rusts are widespread.
Sources
- Agriculture Victoria, Rust in vegetables
- NSW DPI, Bean rust
- Queensland DAF, Rust diseases
Accuracy confidence: high. We update this library as new extension guidance is published.
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