A Wilting and Dying Hydrangea Tree

Identification

• Hydrangeas are susceptible to armillaria root rot or oak root rot fungal disease. The disease is caused by the soil borne Armillaria mellea fungus. Weak or poorly growing plants are more prone to the infection.

Damage

• The fungus infects and rots the water-conducting, cambial tissues in the plants, killing the major roots and lower trunk area first. Initial visible signs include stunted plant growth with discolored, wilting foliage and leaf drop. As disease progresses, branches start dying from the top of the tree. Mushrooms often sprout at trunk base. Gradually, the entire tree is killed.

Control

• Since there are no fungicidal control options for the disease, take preventative measures by preparing the planting ground by removing all old roots from the area. Use resistant hydrangea varieties, especially in areas with known prior cases of the disease. Air-drying infected soil is also a recommended measure cited by the University of California.