Juniperus virginiana, commonly known as eastern red cedar, grows wild in woodlands, prairies and plains throughout much of the United States. Reaching up to 50 feet tall, this evergreen is often grown in home landscapes as a screen or wind break. Under certain conditions, eastern red cedar trees can attract diseases and may transmit some infections to other trees. Following good cultural practices can prevent many of these diseases.
Cedar Rust Diseases
Cedar apple rust, cedar hawthorn rust and cedar quince rust are fungal diseases that transfer from eastern red cedar trees to nearby trees in the Rosaceae family. Eastern red cedars affected by cedar apple and cedar hawthorn rust develop abnormal growths called galls. Cedar quince rust causes a swelling of the branches, rather than producing a distinct gall. During wet spring weather, masses of orange or reddish brown spores form on the galls or swollen branches. The wind carries these spores to nearby apple, crabapple, hawthorn and quince trees. The unsightly galls may cause the die back of twigs but these diseases do not cause significant damage to eastern red cedars. Cedar rust diseases cause more serious problems in the rosaceous host, such as the death of foliage and fruits. Prune out galls when possible to prevent the spread of disease and avoid planting eastern red cedar and rosaceous trees in the same area.
Phomopsis Tip Blight
Phomopsis tip blight causes the death of new growth on eastern red cedars. Infected growth changes colors when infected with this blight, turning yellowish green to reddish brown and finally gray. Lesions form where healthy and diseased areas join together and small stems girdle. Fruiting bodies, black in color, form in the lesions during the late stages of tip blight. When these bodies break open, the spores transfer to other plants. This disease may enter through wounds, so avoiding pruning during wet weather. During dry weather, prune back infected branches and sterilize your pruning tool between each cut with a solution of nine parts water to one part bleach. Apply fungicides according to the directions on the product to prevent tip blight.
The symptoms of kabatina blight are similar to those of phomopsis tip blight, but this disease affects older growth rather than new growth. Kabatina blight typically enters eastern red cedar trees through wounds caused by pruning, winter injury or insect attacks during wet, spring weather. Prevent this disease by pruning out dead stems and increasing air circulation around the tree. Water trees in the morning to allow time for the foliage to dry.