Pestalotiopsis tip blight and dieback, or cryptomeria blight—Pestalotiopsis funerea
Numerous species of conifers can become infected by the Pestalotiopsis funerea fungus that causes tip dieback. In California, cryptomeria (Japanese cedar, Cryptomeria japonica), is most commonly affected.
Identification
Pestalotiopsis tip blight and dieback causes conifer foliage to turn yellow, then dark brown, beginning at the tip. The lower, older foliage is most affected. Tiny black fruiting bodies, barely visible to the naked eye, develop on the affected portions of foliage. Examined with a hand lens, these spore-forming bodies resemble short, black strings.
Life cycle
The pathogen infects conifers that have been weakened by growing in stressful conditions. The fungal spores are spread by splashing water (such as during rain or sprinkler irrigation) and infect weakened conifers when foliage is wet. After infection, disease development and tip dieback may not become apparent until warm, dry weather when the plants' demand for soil moisture increases.
Damage
Stressful growing conditions predispose conifers to fungal infection and Pestalotiopsis tip blight and dieback. Hosts of P. funerea include arborvitae, coast redwood, cypress, Douglas-fir, false cypress, hemlock, incense cedar, Japanese cedar, juniper, monkey puzzle tree, pine, Port Orford cedar, spruce, true cedar, and yew. In California, cryptomeria is most often affected.
Solutions
Avoid crowding conifers when planting. Provide plants with enough space for sufficient sunlight and increased air circulation. This will decrease foliage susceptibility to fungal infection and disease development.
Protect plants from mechanical injury. Provide good growing conditions and appropriate cultural care to keep plants vigorous. Prune out dead foliage and twigs when conditions and foliage are dry. After cuts, consider wiping cutting blades clean and spraying them with bleach or dipping them in diluted bleach after cutting through infected shoots.
Fungicide application is generally not recommended for this disease in landscapes. In plant nurseries where the disease has been a problem, Bordeaux mixture or another copper fungicide is sometimes applied to help prevent this disease. Relying on the above cultural practices can be more effective than fungicides.
Adapted from Arborvitae (Thuja occidentalis)-Tip Blight, Pacific Northwest Plant Disease Management Handbook and Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide, University of California Statewide Integrated Pest Management Program (UC IPM). |
Conifer shoot tip turned brown and yellow and killed by Pestalotiopsis tip blight and dieback.
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