Phomopsis tip blight
in association with Kabatina tip blight can cause severe problems
in nursery stock, transplants and certain juniper species in the
landscape, especially when grown under crowded or stressed conditions.
The disease is most serious on young plants. Although symptoms of
the two blights are similar, the disease cycles are very different.
the causal agent of Phomopsis tip blight, infects new growth
and succulent branch tips of juniper. Older, mature foliage is resistant
to infection. Small yellow spots first appear, then the affected
foliage turns dull red or brown, and finally ash-gray with small
gray lesions that often girdle branch tips. Small black spore-bearing
structures develop in the lesions. Spores are released during wet
weather and disseminated by rain. Infection can occur whenever young
foliage is present and the humidity is high, but most often occurs
in spring and early fall.
Kabatina tip blight,
caused by the fungus Kabatina juniperi, affects year-old
twigs. A wound, usually associated with insect damage, is necessary
for infection. Although infection is believed to occur in autumn,
symptoms are not evident until early spring. The terminal 5 to 15
cm (2 to 6 inches) of diseased branches first turn dull green, then
red or yellow. Small ash-gray to silver lesions dotted with small,
black fruiting bodies are visible at the base of the discolored
tissue. The brown, desiccated foliage eventually drops from the
tree in late May or June. Kabatina tip blight may be confused with
1. Water plants early
in the morning so foliage will dry quickly. Maintain adequate fertility,
but do not overfertilize
2. Prune out and destroy diseased branch tips during dry summer
weather. Avoid wounding plants, especially in spring and summer.
3. Chemical control of these tip blight diseases is usually not
necessary in established landscape or windbreak plantings. Fungicide
applications may occasionally be needed on susceptible junipers.
The causal agent of juniper twig blight must be identified before
making pesticide recommendations, as the timing of applications
and the choice of material will differ.
4. Select resistant varieties when purchasing junipers.
5. Space new plantings to promote air circulation. Avoid heavily
cultivars demonstrated to be resistant to Phomopsis juniperovora:
J. chinensis 'Foemina', 'Iowa,' 'Keteleeri,'* 'Pfitzeriana,'*
'Robusta,' var. sargentii, var. sargentii 'Glauca'
J. horizontalis 'Procumbens'
J. sabina 'Broadmoor,' 'Knap Hill,' 'Skandia'
J. scopulorum 'Silver King'
J. squamata 'Campbellii,'
var. fargesii, 'Prostrata,' 'Pumila'
J. communis 'Ashfordii,' 'Aureospica,' var. depressa
,'Depressa Aurea,' 'Hulkjaerhus,' 'Prostrata Aurea,'
'Repanda,' var. saxatilis, 'Suecica'
J. virginiana 'Tripartita'
* Cultivar is also resistant
to Kabatina tip blight.
from Ohio State University Extension, 1999. Wayne Sinclair, Howard
T. Lyon, and Warren T. Johnson. 1987. Diseases of Trees and Shrubs,
Cornell University Press: NY.