White rust
White rust, caused by the pathogen Albugo candida, is a disease that affects a variety of plants, particularly those in the Brassicaceae family. It is characterized by the appearance of white, blister-like pustules on the leaves and stems, which can lead to distorted growth.
About this problem
White rust is a plant disease caused by the oomycete pathogen Albugo candida, which primarily affects members of the Brassicaceae family, including mustard, radish, and broccoli. The disease manifests as white, blister-like pustules on the undersides of leaves and sometimes on stems. These pustules contain spores that can spread the disease to other plants. Over time, infected plants may exhibit distorted growth and reduced vigor, although the disease is generally more cosmetic than fatal. White rust can be confused with downy mildew due to similar symptoms, but the distinct white pustules help differentiate it.
Symptoms
- White blister-like pustules on leaves
- Distorted leaf and stem growth
- Yellowing of affected areas
- Stunted plant growth
Cause
White rust is caused by the oomycete Albugo candida. This pathogen thrives in cool, moist conditions, which facilitate the spread and germination of its spores.
Conditions that favour it
- Cool temperatures
- High humidity
- Frequent rain or overhead watering
- Poor air circulation
Lifecycle and spread
Albugo candida spreads through spores that are dispersed by wind and water. The pathogen overwinters in plant debris and soil, and can infect new plants in the spring. Breaking the cycle involves removing infected plant material and improving air circulation.
Plants most affected
- Mustard
- Radish
- Broccoli
- Cauliflower
- Cabbage
- Turnip
- Spinach
- Beet
Treatment
Educational information only, and not a substitute for professional diagnosis. Identify the problem before treating it, and check that any product is registered for this plant and this use where you live.
Cultural control
- Increase plant spacing for better air circulation
- Avoid overhead watering
- Remove and destroy infected plant debris
- Rotate crops annually
Organic options
- Neem oil
- Baking soda spray
- Copper-based fungicides
Chemical options
- Chlorothalonil Used to manage fungal diseases
- Mancozeb Used to control fungal infections
Read and follow the product label. The label is the legally binding instruction. Confirm the product is registered for this plant and for this use in your area before applying it.
Prevention
- Plant resistant varieties
- Ensure good drainage in planting areas
- Practice crop rotation
- Maintain proper plant spacing