Cercospora Twig Blight
This disease is caused by the fungus Cercosporasequoiae var. juniperi. It begins by
infecting the oldest needles that are located on the lower branches, inside of
the plant. As disease development progresses, the needle browning spreads
upward and outward. Branch tips usually remain healthy and green. Needles of
spur branches turn brown and die usually in the late summer, leaving a plant
with an inner crown devoid of foliage. This disease is sometimes confused with
Each of these diseases requires
similar methods of control. First, closely inspect the entire plant, since
symptoms of tip blight and twig blight can be caused by other problems, such as
drought, overwatering or root injury.
Purchase disease-resistant varieties that are healthy with no
evidence of dead or dying twigs. Do not stress junipers by planting them in
shaded or poorly drained locations. Plant junipers in areas with good air
circulation to promote rapid drying of the needles. Do not crowd plants, and
avoid using sprinkler irrigation. Promptly prune and remove any diseased or
browning branches as they occur. Except on highly susceptible cultivars,
pruning will usually control these diseases.
If chemical control is necessary, fungicides are available to
provide protection, but they must be applied before infection occurs. Select a
fungicide labeled for use on junipers containing one of the following:
mancozeb, thiophanate-methyl or copper salts of fatty acids.