Eastern red cedar trees (Juniperus virginiana) are generally problem free in their native habitat. They thrive in sandy or clay soils as long as the soil Ph is below 8.0. Eastern red cedars grow in sun or shade and in poorly drained or dry sites from East Texas to Florida and north to Canada. However, problems do occasionally appear when planted in the landscape. Not all are fatal, but they can make the tree unsightly and lead to an overall decline in the tree's health. Problems to look out for are cedar-apple rust, bagworm, annosum root rot and phomopsis blight.
Cedar Apple Rust
Cedar apple rust can be seen as orange horn-like gelatinous growths at the end of branches in the spring. When the weather warms the gel turns to a hard mass called a gall. Cedar apple rust spreads to apple trees that are not resistant where it damages the leaves and fruit. However, on cedar trees it is little more than a curiosity that can't harm the tree.
Bagworms can cause major damage by eating the foliage of the cedar tree in the spring. In early summer the worms create bags made of silk and foliage that hang on the limb of the tree. The bags are held to the limb by a loop that is very tough and can last a year or more and girdle the limb causing death of the area that is below where the bag is attached. Control by spraying a pesticide containing Bt (Bacillus thuringiensis) or spinosad in spring when worms are feeding. There is no control once the worms have retreated to their bags to pupate.
Annosum Root Rot
Annosum root rot is caused by the fungus Heterobasidion annosurn. It is common in areas with well-drained sandy soils and spreads through the soil killing trees it infects. It proliferates in areas where trees are cleared and stumps are left to rot. The most important symptom of annosum root rot is the presence of conks, or hard mushroom-like growths growing from the base of a cedar tree. Control is difficult if multiple trees are affected. No chemical control is available.
Phomopsis leaf blight spares older trees but kills saplings. It is a fungal disease that causes yellowing of leaf tips and makes cedars planted in the landscape unsightly. The only fungicide approved for control of phomopsis leaf blight is benomyl.