A slowly-dying mugo pine shrub - Ask Extension
Hello, OSU folks! We have two mugs pines in our back yard, planted about 4-5 feet apart. They're each about 3-4' tall, and each has a canopy spread ...
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A slowly-dying mugo pine shrub #867942
Asked May 10, 2024, 7:22 PM EDT
Hello, OSU folks! We have two mugs pines in our back yard, planted about 4-5 feet apart. They're each about 3-4' tall, and each has a canopy spread of some 5-6'. One of the shrubs has been dying back, with needles turning brown and branches dying. I've cut those dead branches away on two occasions; about half of the one shrub has died at this point. The die-back began in early winter, 2023. The other, oddly enough, seems to be doing fine!
I'd appreciate any ideas and/or suggestions you might have. Thanks in advance.
Washington County Oregon
Expert Response
Mugo pines are good landscape plants, but in our area they do sometimes fail, and you might never know the reason. Still, with detective work, maybe we can make a good guess.
Provide a photo showing your whole landscape area. Clues can be gathered from the surrounding plantings.
How long have they been planted here? Describe watering and fertilizing.
What treatments have been done in the area of the shrubs? Roots extend beyond the edge of the trees. This can mean that treatments for lawn or neighboring flower beds need to be safe for use on conifers. Likewise, consider possible herbicide drift from turf application or granular weed suppression applied to bark areas nearby.
There is a fungal needle blight, these pines can have. Share a close photo of some needles from the area where the needles are just beginning to change color.
Also, put on your gloves and really follow some of those branches just beginning to discolor. Can you find obvious problems with those branches? Sometimes there’s a bark canker from disease or insect. Or you may find branch crotches are pulled open and split, like from an animal walking through it (children chasing a ball, or a big raccoon are examples).
It could also be a root problem, and those are often not treatable. These pines need well-drained soil, and our wet winters can eventually cause root rots. Has anything changed in the watering or winter drainage? Sometimes a break in irrigation can overwater an area that once was dry, for example.
I want to share a prior Q&A, here, from Michigan rather than Oregon, but the plants look similar. That answer includes a link about the needle blight for further reasearch.
Provide a photo showing your whole landscape area. Clues can be gathered from the surrounding plantings.
How long have they been planted here? Describe watering and fertilizing.
What treatments have been done in the area of the shrubs? Roots extend beyond the edge of the trees. This can mean that treatments for lawn or neighboring flower beds need to be safe for use on conifers. Likewise, consider possible herbicide drift from turf application or granular weed suppression applied to bark areas nearby.
There is a fungal needle blight, these pines can have. Share a close photo of some needles from the area where the needles are just beginning to change color.
Also, put on your gloves and really follow some of those branches just beginning to discolor. Can you find obvious problems with those branches? Sometimes there’s a bark canker from disease or insect. Or you may find branch crotches are pulled open and split, like from an animal walking through it (children chasing a ball, or a big raccoon are examples).
It could also be a root problem, and those are often not treatable. These pines need well-drained soil, and our wet winters can eventually cause root rots. Has anything changed in the watering or winter drainage? Sometimes a break in irrigation can overwater an area that once was dry, for example.
I want to share a prior Q&A, here, from Michigan rather than Oregon, but the plants look similar. That answer includes a link about the needle blight for further reasearch.
