Purdue Landscape Report – Tip Blights of Juniper: Junipers have to be my favorite group of evergreens, behind a select few pine species. They have a fantastic fragrance, are evergreen, many can tolerate drought, are an ingredient in gin (definitely a bonus), and work well in a variety of landscape uses, including as a barrier plant. They look great year round, except when they have tip blight.
Tip blight is a common disease in nurseries and landscapes that cause branch tips to die back fairly quickly starting in the spring. Infected branches become chlorotic, progressing from light green to yellow, before turning brown as the season continues. Black fungal structures will develop in the transition zone between affected foliage and green, healthy tissue. Some of the infected scales may turn gray in color, surrounding these structures.
Two fungi cause tip blight, Kabatina and Phomopsis, and knowing which one you have is important to determine your management strategies. Both fungi produce similar symptoms and similar fungal structures,so the presence of tiny black dots cannot help separate these diseases. Both fungi also infect a range of hosts, including arborvitae, cypress, Douglas fir, true firs, yew, Cyptomeria, and Chamaecyparis, but these are not as susceptible as juniper species.
Kabatina infects young, new growth during the growing season, but infected twigs remain green until winter and the following spring . . .
Borers of Pines and Other Needle Bearing Evergreens in Landscapes, The Education Store, Purdue Extension resource center
Ask an Expert Question: Blue Spruce dying, what can I do?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Why Spruce Trees Lose Their Needles, Purdue Extension
Diseases Common in Blue Spruce, Purdue Extension
Purdue University Invasive Species
John Bonkowski, Plant Disease Diagnostician
Purdue Botany and Plant Pathology