Staghorn Sumac Diseases

Verticillium Wilt

• Verticillium wilt is caused by a fungus of the same name that infects sumacs and a range of other host plants through a plant's root system. An infected plant may exhibit leaf curling, wilting and discoloration and branch dieback. Dieback and sumac death usually occur gradually over multiple years. Good cultural care practices, especially proper watering, are crucial, as Verticillium fungi invade stressed roots. If one staghorn sumac plant is affected by Verticillium and there are still healthy sumacs or other desirable plants in the area, remove the infected sumac promptly, capturing as much of the root system as possible.

Nectria Canker

• Staghorn sumacs are potentially affected by a fungal pathogen in the genus Nectria, although this pathogen generally only attacks plants that are already stressed or weakened. This fungus causes branches to die back and branches that are killed develop small pink fungal pustules. Prune off infected portions of the sumac when conditions are dry, making any cut into healthy tissue below the infection and just outside a branch collar where the branch meets a larger branch or the main stem, and dispose of removed parts of the sumac away from desirable vegetation.

Powdery Mildew

• Powdery mildew is a fungal disease easily recognized by the powdery white fungal growth that appears on the leaves and shoots and sometimes flowers and fruits of sumacs and other hosts. Unlike many other fungi, powdery mildew does not require free moisture on foliage to infect a plant. Temperatures between 60 degrees and 80 degrees Fahrenheit and shady conditions encourage powdery mildew growth. To minimize problems with this disease, plant the staghorn sumac in a spot with full sunlight or prune out branches on the sumac and adjacent vegetation to increase the amount of sunlight reaching sumac foliage. Also avoid excessive or fast-release nitrogen fertilizer applications near the staghorn sumac,

Leaf Spots

• Staghorn sumacs may occasionally develop fungal leaf spots, which appear as round or irregular spots of varied color, depending on the responsible pathogen. Leaf spots are rarely serious; fungicides are typically not warranted and a healthy sumac will recover quickly from this type of fungal infection. Rake up and dispose of fallen sumac leaves and other debris around the staghorn sumac as it appears and avoid wetting the staghorn sumac with sprinkler irrigation or other splashing water.

Water Management Problems

• The staghorn sumac requires well-drained soil to thrive and will suffer in heavy soils or when irrigation or rainfall is excessive. A sumac plant receiving too much water may develop blisters on its leaves that eventually turn tan and corky. Too much water around roots interferes with healthy root function, causing leaf wilt, discoloration and death and, in severe cases, entire plant death. Excessive, constant moisture around the sumac's root system also leaves it vulnerable to diseases like Verticillium wilt and invasion by rot and decay fungi.