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Plant NameTypeDescription 
Cedar flaggingCedarDiseaseEvergreen plants naturally shed some old foliage each year. Stress factors, such as lack of sufficient water, hot winds, construction damage or other root disturbance, poor planting procedures, or recent planting can promote flagging. Brown foliage develops on the tree or shrub in mid- to late summer and is very obvious by early fall. The affected foliage consists of older growth formed in previous years. Foliage developed during the current year (at the branch tips) remains green. These brown branchlets are called flags and are generally spread uniformly throughout the canopy. Affected foliage may begin to drop during hot, dry weather. Most of the dead foliage is blown out of the plant by the wind in fall and winter, and the plant typically resumes its healthy appearance.
Leaf blightCedarDiseaseLeaf blight is a fungal disease. The symptoms typically appear first in late spring as bleached spots followed by brown or black cushion-like fungal fruiting bodies. Infected foliage may be anywhere on the plant. Individual leaves are killed by the fungus and turn a light tan to gray color. As the fruiting bodies drop out of the leaves, deep pits are left in the dead tissue. The infected tissues often have a "scorched" appearance. Infected leaves often drop in the fall. Western red cedar (Thuja plicata) is most commonly infected, particularly the cultivars 'Atrovirens' and 'Excelsa'. A similar disease attacks junipers.
Port Orford cedar root rotCedarDiseasePhytophthora root rot on Port Orford cedar is usually a problem only in areas with poor drainage or where flooding occurs. The fungus attacks the roots, which rot and die. The infection moves up into the crown, where the cambium (soft inner bark) turns reddish-brown or caramel in color instead of the normal white to greenish color. Older trees may develop cankers on the trunk, which are a dark reddish-brown when cut. The cankers may be accompanied by split bark and oozing pitch. Lower branches wilt, turn dark red, and die back. Younger trees are often killed outright, while infected mature trees may show wilting, branch dieback, and/or gradual decline.
Seiridium cankerCedarDiseaseSeiridium cardinale and Phaeobotryon cupressi are fungal pathogens which cause yellowing or browning of the foliage. The result is flagging, the dieback of branch tips and entire branches of trees in a random distribution throughout the canopy. Cankers may be observed which are wounds or necrotic lesions often sunken beneath the surface of the stems or branches. Fungal spores can be spread by rain, irrigation water, insects, or pruning tools. The spores can enter through wounds or cracks in the bark, insect holes, or storm damage. Environmental factors such as drought or storm damage may cause stress on trees which make them vulnerable to these fungi. In the Pacific Northwest Incense cedar is particularly susceptible to this disease. Other possible hosts might include Leyland cypress, False cypress, Monterey cypress, Arborvitae, and Junpier.