Sumac Leaf Spot

Symptoms by part

Causes

• Prolonged periods of high humidity
• Frequent rainfall that keeps foliage wet for extended hours
• Poor air circulation around the plant canopy
• Overcrowded planting locations

Could be confused with

• Sunscald · Sunscald typically appears as bleached or scorched patches on leaves exposed to intense direct light, rather than circular, defined spots.
• Nutrient deficiency · Deficiencies usually cause yellowing or discoloration between the leaf veins rather than distinct, dark, circular spots.

Treatment

1. Prune away and destroy any heavily infected leaves to reduce the amount of fungus present.
2. Clear away all fallen leaves from beneath the tree to prevent spores from overwintering in the soil.
3. Thin out crowded branches to improve airflow through the center of the plant.

Without chemicals

• Pruning for better air circulation
• Sanitation by removing and disposing of infected leaf litter
• Watering at the base of the plant to keep foliage dry

Chemical options

• Sulfur, apply as a dust or spray to foliage during the early stages of infection, follow the label.
• Potassium bicarbonate, apply as a foliar spray to neutralize fungal spores, follow the label.

Preventing it

• Space plants properly to ensure good air movement.
• Avoid overhead irrigation that wets the leaves.
• Clean up and remove all leaf debris from the ground every autumn.

When to act

Act as soon as you notice the first spots appearing on the leaves. You do not need to remove the plant, as this is a cosmetic issue that rarely causes long term harm.

Questions people ask

Will Sumac Leaf Spot kill my tree?

No, it is generally a cosmetic issue that does not kill the tree.

Should I cut down my sumac if it has leaf spot?

There is no need to remove the tree, as simple sanitation and pruning are usually enough to manage the problem.

Plants it affects

• Staghorn sumac