Poor watering techniques, pests and bacterial or fungal infections are causes of arborvitae disease in trees. Disease can spread to healthy trees when a diseased tree is located nearby, or when equipment, such as pruning shears, aren't properly sanitized after use. Trees that are stressed are often more susceptible to disease. To prevent disease, provide the tree with proper care throughout the year, and avoid over-watering the tree. Use fungicide, beneficial bacteria, beneficial fungus or pesticide as needed.
Stress is a common cause of arborvitae disease. Trees become stressed when they do not have the proper nutrients, or when the tree is planted in a location that doesn't suit its light requirements. As a result of the stress, the tree is unable to resist fungal and bacterial infections.
Pests are also a common problem that cause diseases, such as sooty mold, to develop on otherwise healthy trees. To revive a diseased tree, apply the proper fungicide or pesticide, prune away dead or diseased branches, and follow the recommended procedure for mulching, fertilizing and watering the tree.
To prevent the spread of disease, sterilize the equipment after caring for each tree to prevent the spread of arborvitae disease, and examine the trees regularly for signs of damage. Remove old and infected wood, such as dead stumps, to help prevent arborvitae disease among healthy trees.