Identifying and Treating Sumac Diseases

Sumac plants are members of the Rhus family. Not many sumac diseases are known since these plants are resistant to most garden pests/infections. However, some sumac infections can spread quickly in wet conditions, destroying the inner stem and roots of sumacs. You should know how to detect and treat destructive sumac diseases like powdery mildew and shoot blight.

Disease 1 - Sumac Powdery Mildew

It is caused by the Phyllactinia fungus.


The most easy-to-detect symptoms include the presence of white or gray-colored powdery fungus on the leaves. The leaves show stunted growth and are often covered with a crust of fungal threads.


  • Improving ventilation in the garden bed is vital.
  • Create more space between the garden rows to increase air circulation.
  • Water at the base of plants to avoid water splashing that can encourage bruising of young plants. Bruised plant surfaces are more vulnerable to mildew infection.
  • Chemical treatment can be done by mixing Thiophanate-methyl in the anti-fungal preparation.

Disease 2 - Sumac Shoot Blight

It is caused by the Botryosphaeria bacteria.


Small, discolored patches develop on the stems of affected sumacs. These are canker spots and are more common in the mature stems. The cankers are oval or circular in shape and have defined, darker outer edges.


The infection can be best controlled by limiting plant wounding. Young sumacs are more prone to blights if pruned harshly.

Prune with lightweight shears.

Dip the pruning equipment in an anti-fugal formulation before pruning.

Blight spreads quickly through the garden soil bed. Rotate the garden crops each year.