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University
of Rhode Island GreenShare Factsheets
Juniper
Tip Blights
Phomopsis juniperovora & Kabatina
juniperi
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.
Phomopsis juniperovora, 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 winter injury.
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 shaded areas.
Juniper (Juniperus) 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.
Adapted 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.
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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