Symptoms include the die back of the tips of branches that are equal
to or smaller than the thickness of a pencil. Infected foliage becomes
pale, then reddish brown and then turns brown or ash-gray after death.
To confirm the diagnosis of
Phomopsis as the cause of the twig
die back, scrape away the thin bark until you reach living wood. There
should be a sharp line between the discolored dead wood and healthy wood.
Also, look at the base of the ash-gray colored scale needles for small,
black fruiting bodies.
These fruiting bodies form the spores that cause new infections. In
wet weather, spores ooze from the fruiting bodies and splash onto new foliage.
The spores are produced year around and infect yellowish green juvenile
tissue. The darker green mature foliage is resistant to infection.
Junipers generally have two flushes of growth under natural conditions,
one in late April through June and another in late August to September.
When growth coincides with wet, warm weather or frequent overhead watering,
disease can be severe.
Most severely diseased plantings are the result of excessive wetness.
This may be due to the site being poorly drained, shaded or over watered
by irrigation. Under continuously wet conditions, an entire plant may die.