Juniper Blue Pacific problem - Ask Extension
I have an established groundcover (15+ years) with Juniper Blue Pacific. In the last 2-3 years I have had slowly progressive loss of some of the plant...
Knowledgebase
Juniper Blue Pacific problem #919168
Asked October 03, 2025, 12:45 PM EDT
I have an established groundcover (15+ years) with Juniper Blue Pacific. In the last 2-3 years I have had slowly progressive loss of some of the plants (see photos depicting bare areas, as well as incipient loss). I have replaced some specimens, some of which have died and others are still alive. I haven’t noticed any insect damage. The dead areas seem randomly located amongst the landscape. Do you have any suggestions? Thanks. Dan
Montgomery County Maryland
Expert Response
It's hard to determine what caused the dieback, but several factors are possible: vole damage, if they roam into that planting bed and chew on branch bark; a fungal twig blight; or root stress from too much or too little soil moisture at some point (despite their drought tolerance, junipers can still be stressed or damaged by getting too dry). Weather has a large impact on plant disease spread and severity, and sometimes an alignment of weather conditions (especially periods of leaf wetness, whether from rain, dew, or irrigation) allows plants to develop infections when they had not in the past.
Since mass plantings of any one genus/species can be more vulnerable to pest or disease outbreaks, consider putting in other groundcover species when you need to replace any failing junipers in the future. The linked page provides some ideas, though it's not an exhaustive list.
Fungicide won't be able to cure any existing infections (and before it's use as a preventative was considered, a fungal culprit should be confirmed first), but you can trim off any branches or branch tips that have completely browned. Branches with live tip growth but brown basal needles shouldn't be trimmed off, and while they may be an eyesore if bare areas are exposing them to view, eventually those brown needles should fall off on their own. If branches surrounding a bare area of wood remain healthy, they can slowly fill in that gap.
If voles are present and contributing to damage, they tend to be fairly short-lived in terms of life cycle and may be controlled by a predator (hawk, owl, snake, fox, etc.) without you needing to do anything. Otherwise, if you find evidence of vole problems, and they're worsening, lethal trapping tends to be the most practical and effective solution when intervention is needed. (Do not use poison bait, due to the risk of harming other wildlife or pets.)
For the time being, you can reduce any stress on the remaining plants by monitoring them for watering needs, as many areas (including Montgomery County) have been in or near drought status for several weeks. Junipers do have good drought tolerance, but sometimes having to deal with that stress can predispose shrubs and trees to secondary problems that can't be treated, such as opportunistic fungi like Botryosphaeria canker.
Miri
Since mass plantings of any one genus/species can be more vulnerable to pest or disease outbreaks, consider putting in other groundcover species when you need to replace any failing junipers in the future. The linked page provides some ideas, though it's not an exhaustive list.
Fungicide won't be able to cure any existing infections (and before it's use as a preventative was considered, a fungal culprit should be confirmed first), but you can trim off any branches or branch tips that have completely browned. Branches with live tip growth but brown basal needles shouldn't be trimmed off, and while they may be an eyesore if bare areas are exposing them to view, eventually those brown needles should fall off on their own. If branches surrounding a bare area of wood remain healthy, they can slowly fill in that gap.
If voles are present and contributing to damage, they tend to be fairly short-lived in terms of life cycle and may be controlled by a predator (hawk, owl, snake, fox, etc.) without you needing to do anything. Otherwise, if you find evidence of vole problems, and they're worsening, lethal trapping tends to be the most practical and effective solution when intervention is needed. (Do not use poison bait, due to the risk of harming other wildlife or pets.)
For the time being, you can reduce any stress on the remaining plants by monitoring them for watering needs, as many areas (including Montgomery County) have been in or near drought status for several weeks. Junipers do have good drought tolerance, but sometimes having to deal with that stress can predispose shrubs and trees to secondary problems that can't be treated, such as opportunistic fungi like Botryosphaeria canker.
Miri
