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.

Symptoms and Disease Cycles:

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.

Control:

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.