Currant Rust

Symptoms by part

Causes

• High humidity levels around the foliage.
• Poor air circulation within the plant canopy.
• Extended periods of moisture on the leaf surfaces.
• Presence of nearby alternate hosts like white pine trees.

Could be confused with

• Leaf Spot · Leaf spot typically creates darker, more defined brown or black lesions rather than the powdery, rust colored pustules found with rust.
• Nutrient Deficiency · Deficiencies usually cause uniform yellowing or discoloration across the entire leaf rather than distinct, raised spots or pustules.

Treatment

1. Prune away and destroy any infected leaves as soon as they are spotted to reduce the spread of spores.
2. Thin out the center of the bush to improve airflow and allow the foliage to dry out faster after rain.
3. Clear away all fallen leaves from beneath the plant at the end of the season to remove overwintering spores.

Without chemicals

• Prune the plant to open up the canopy.
• Improve spacing between plants to encourage better air movement.
• Water at the base of the plant to keep the foliage dry.

Chemical options

• Sulfur, apply as a dust or spray to the foliage during the early stages of infection, follow the label.
• Potassium bicarbonate, spray onto the leaves to alter the surface pH and inhibit fungal growth, follow the label.

Preventing it

• Choose varieties known for better resistance to fungal diseases.
• Ensure the garden site has excellent drainage.
• Avoid overhead watering that keeps leaves wet for long periods.
• Remove any nearby alternate host plants if possible.

When to act

Act as soon as you notice the first orange spots on the leaves. If the plant loses most of its leaves every year despite your efforts, consider replacing it with a more resistant variety.

Questions people ask

Will Currant Rust kill my bush?

It is unlikely to kill a healthy, established bush, but it will certainly stress the plant and reduce your harvest.

Can I eat the fruit from a plant with rust?

Yes, the rust affects the leaves and does not make the fruit unsafe to eat, though the plant may produce less fruit overall.