Also known as the Nootka false cypress, the Alaskan cedar is a moderately-sized evergreen that can reach mature, untamed heights up to 90 feet. This evergreen tree produces bluish-green needles on feathery branches that naturally droop, causing a weeping appearance. A relatively disease-resistant tree, the Alaskan cedar is susceptible to only a few diseases, which are most injurious to young developing trees and ailing Alaskan cedars of any age.
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Phomopsis blight is a fungal disease that is most damaging to the young Alaskan cedar. The fungal spores of this disease are most active during the warm, wet periods of the growing season. Transported by rain and wind, these infectious spores attack the young developing shoots and needles of the Alaskan cedar. The infection causes the needles and shoots to become discolored while they are simultaneously, but gradually, killed. The infected areas also develop cankerous lesions which girdle the supporting stems. The Alaskan cedar takes on a scorched appearance as it becomes completely overwhelmed by the disease.
Phytophthora Root Rot
Phytophthora root rot is a fungal disease that develops from heavily saturated soil environments. This soil-borne disease infects and rots the Alaskan cedar’s root system. The inhibited root system becomes unable to pass nutrients and water throughout the tree which causes the cedar to die, essentially, from starvation. The Alaskan cedar’s needles become discolored and the tree experiences defoliation and growth stunt. There is no cure for phytophthora root rot. Infected Alaskan cedars should be removed and destroyed. Phytophthora spores can live for several years in the soil without a host, so avoid planting any new Alaskan cedars in the infected area.
Port Orford Cedar Root Rot
Port Orford cedar root rot is a rot disease caused by a phytophthora fungal strain, known as phytophthora lateralis. Like phytophthora rot, Port Orford cedar rot is soil-borne and most active in waterlogged soils. More aggressive than phytophthora rot, however, Port Orford cedar root rot infections cause rapid decline of the infected Alaskan cedar and quickly kill the tree. The initial infection causes the cedar’s wood to become water-soaked, while the roots are quickly decayed by the infection. The foliage loses color and wilts before bronzing and defoliating from the tree. While Port Orford cedar rot may take several years to kill a mature Alaskan cedar, the infection can kill the sapling Alaskan cedar within several weeks. Port Orford cedar root rot has no cure and infected trees should be removed and destroyed.
Leaf scorch is a physiological disease caused by poor environmental conditions. Long periods of drought, injury from chemical treatments, winter salt injury and lack of nutrients are just some the factors that contribute to leaf scorch infections. The infected Alaskan cedar experiences needle discoloration, defoliation, loss of vigor and growth stunt. This disease is easily reversed by improving the cedar’s care and maintenance routine, though severely infected trees can be permanently injured.