Rust (various)
Puccinia spp.; Uromyces spp.
Orange, brown or black powdery pustules on leaf undersides. Common on beans, garlic, leeks and silverbeet.
Background
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.