Juniper Tips Dying?
If they are, you likely have juniper tip blight, or phomopsis.
This is a fungus that attacks the growing tip of the juniper, usually in spring when the temps are mild, around 60 F / 15 C or so, and during humid or wet weather. It attacks many species of juniper. Native North American junipers like Rocky Mountain Juniper are from arid areas and are particularly susceptible, but it is also found on shimpaku junipers. Needle junipers seem least susceptible but they also can be attacked.
Juniper Tip Blight, or phomopsis
This is a serious disease that can kill the branch and ultimately the tree. Do not ignore it if you have it. Again, this is a disease most active in the spring although you might see the fungal damage any time of year. Cutting away affected areas helps track its progress.
If you’ve ever seen ground cover junipers with dead patches, it’s very often this fungus. Other tip blights may look similar, like kabatina, but phomopsis is the main one.
Once you have it this disease can take a while to get rid of, often taking a year of spraying. Control is with fungicides, sprayed late winter through late spring, often 2-3 times a month. Go for complete coverage, to dripping. Common fungicides like Daconil won’t work with this disease, you will need others like Mancozeb, Heritage, or Cleary’s (always read labels very carefully, dosages and scheduling differs for all of them). Those who live in moist climates may need prophylactic sprays in the springtime to stay on top of the problem and to have disease-free juniper bonsai.
If you’re not sure you have this fungus—or any disease—it’s wise to get confirmation with a lab test. Try agricultural universities and private tree care professionals, many have labs that can diagnose pathogens. General guidelines for handling samples: Cut off some fresh, diseased areas, place a lightly damp towel in a ziplock bag and seal, label it carefully with date and species, and put in the mail immediately—overnight service to the lab is usually recommended. If this is impossible refrigerate specimen until sent. Close up photographs are also often helpful. Labs will usually come with their own instructions, however.