University of Maryland Extension

Juniper Twig Blights - Phomopsis and Kabatina

close up of phomopsis
Phomopsis symptoms on juniper

Key Points

  • Juniper twig blights caused by the fungi Phomopsis and Kabatina are two of the most damaging diseases to junipers in the northeast.
  • Susceptible species include eastern, red, and white cedar varieties as well as Chinese, common, creeping, needle, Rocky Mountain, savin, shore, and Utah junipers. To a lesser degree, these diseases can also infect American and Oriental arborvitae, hinoki cypress, and English yew.
  • There is however wide variation between susceptible and resistant cultivars within these plant groups.
  • Very few plant cultivars are resistant to both diseases.
  • Cultivars resistant to both kabatina and phomopsis include Juniperus chinensis 'Phitzeriana aurea' and J. chinensis var. Sargentii 'Glauca'.
  • Management strategies

symptoms of phomopsis on juniperphomopsis symptoms closeup
Phomopsis on juniper                              Closeup of phomopsis on juniper needle    

Phomopsis blight

  • The primary symptom of Phomopsis blight is the browning and dieback of new shoot tips in the spring.
  • Phomopsis blight is caused by the fungus Phomopsis juniperovora.
  • The fungus over winters on previous blighted twigs and bark.
  • Primary infection occurs during cool wet spring weather but occasional fall infection is possible.
  • Spores are produced from small, black fungal fruiting structures on these old blighted shoots.
  • During wet rainy weather, spores are released and splashed onto the new young growth.
  • Older, unwounded shoots are not susceptible. Blighted twigs first turn pale green and are brown by early summer. Shoots are usually killed back to the previous season's wood.
  • Sunken dark lesions called cankers are formed at the junction of live and dead wood.

Kabatina blight

  • Kabatina blight primarily attacks and kills juniper twigs 1 year or older during warm, summer weather, unlike Phomopsis blight, which usually kills new shoots in the spring.
  • Kabatina blight is caused by the fungus Kabatina juniperi.
  • In juniper cultivars that take on purple-colored winter foliage, shoots infected by the Kabatina fungus late in the season will remain green.
  • Blighted shoots eventually turn brown by late winter and provide a source of infection during the next growing season.
  • Small, black fungal fruiting bodies that produce infective spores form on the blighted twigs.
  • During wet weather, spores are released and washed onto additional stems and twigs.
  • Kabatina requires a small wound to invade the plant usually caused by insect or mite feeding, abrasion by adjacent branches, winter damage or pruning cuts.

kabatina blight symptomskabatina spore close-up
 Kabatina blight infected juniper               Closeup of kabatina spores

Management Strategies

  • Removal of old dead twigs and branches is very important for the control of both diseases.
  • Previously infected dead shoots should be removed early in the spring before new growth begins to lessen the number of infective spores.
  • The best management option is to select resistant juniper cultivars, however, few cultivars are resistant to both diseases.
  • Phomopsis blight can be controlled with registered fungicides if applications are made before new growth starts in the spring and continued as long as new growth is produced.
  • However, at present, there are no fungicides effective for Kabatina blight.

Rev 2020

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