Cytospora canker is a fungal disease that primarily attacks spruces among other host trees, causing unsightly cosmetic damage as well as plant death in severe cases. Become acquainted with preventive treatments as well as management methods in case an infection occurs on your spruce. Through thoughtful selection and care, you can continue enjoying a healthy home landscape.
Fungal infections most often attack weakened, stressed or injured trees. A vigorous, well-maintained spruce tree is more likely avoid the need for specialized treatment in comparison to a neglected plant with injuries or in decline. Grow your spruce trees in the full sun evergreen trees prefer, according to the University of Wisconsin-Extension. Spruces thrive in moist, well-drained soil and benefit from a 2- to 4-inch layer or organic mulch on surrounding soil that aids in moisture retention and weed control.
Cytospora canker of spruce trees is caused by the fungal pathogen Leucostoma kunzei, according University of Rhode Island Landscape Horticulture Program. This fungus has a particular preference among spruce species for Colorado blue spruce, black spruce and white spruce. Transported sporadically on water, wind and contaminated equipment, cytospora canker pathogens invade through wounds in the spruce tree, resulting in a need for treatment.
Cytospora canker of spruce trees results in browning of needles during the spring and summer as well as discoloration of bark that becomes an orange, brown or black hue in localized areas. Cankers or lesions of dying plant tissue form on bark as well, creating areas that sink into the tree's surface while excreting a white ooze. Infected brown needles fall from the tree in winter and when left untreated, spruce trees die within several years of infection, according to the Ohio State University Extension.
Choose resistant trees over highly susceptible trees when you know your region commonly experiences cytospora canker, if an infection has already occurred and especially when replanting where an infected tree has been removed. The Serbian spruce (Picea omorika) is resistant to this fungal infection, according to the University of Rhode Island Landscape Horticulture Program. Other resistant species include, but are not limited to, most junipers, elms, maples and pines, according to the Colorado State University Extension.
Chemical control methods are not available for cytospora canker disease of spruce trees. For treatment, avoid injury to prevent points of entrance for fungi. Remove and destroy affected plant parts during dry weather; avoid pruning during wet conditions. Always sanitize pruning shears between each cut on the tree and from use on one spruce to the next plant to avoid transmission of fungal pathogens. If your region experiences drought, increase your watering to a depth of 18 to 24 inches, according to the Ohio State University Extension, as these conditions increase vulnerability to infection. Contact a licensed professional or your local county extension agent for assistance.