Colorado Blue Spuce needle drop - Ask Extension
Good morning,
I was hoping you might be able to help with a blue spruce health issue. This is a young tree approx 10' tall and was planted as a 5' ...
Knowledgebase
Colorado Blue Spuce needle drop #815169
Asked October 25, 2022, 10:33 AM EDT
Good morning,
I was hoping you might be able to help with a blue spruce health issue. This is a young tree approx 10' tall and was planted as a 5' tree approx 5 years ago that over the last couple of years has developed a needle drop/dying branch issue especially on the older, lower branches. I did some research and thought it might a fungal infection needle drop disease. I have used a copper based fungicide spray every 10 days or so over a two month period with no change. I know that this can take a long time to resolve, assuming the fungus is the problem, but it seems to be getting worse.
I live about 2 miles from Brookside Gardens and can cut a branch off and bring it to your facility if you think that might help. In the meantime, here are some pictures. The tree had a nice shape and would love to save it if I can so any help you can provide is greatly appreciated.
More photos are available but these show the problem best. Plant location has plenty of mostly afternoon sun. Not sure of the soil condition but the plant was thriving for the first 3 years after being planted. No other trees within 40' though there is a 45' Pin Oak that does cast some morning shade on the tree. No other blue spruces on the property or even nearby as far as I can tell.
Thanks,
Steve
Montgomery County Maryland
Expert Response
Hello Steve,
While needle cast diseases can be quite common on spruce (particularly Colorado blue spruce) in our region, this appears to be mainly normal needle shed as the plant ages. It might exacerbated by any shade or root competition the tree is experiencing due to nearby mature trees, and/or due to periods of drought during summer since spruce are not well-suited to our growing conditions in the mid-Atlantic, despite how popular they seem to stay in local horticulture. (Even though you mention the nearest tree is forty feet away, its roots are still growing throughout that area and competing to some degree with anything growing in the same space.)
All evergreens do shed some of their oldest foliage/needles each year, often in autumn, and spruce needles can turn yellow or brown before falling. The oldest foliage will be on the innermost portions of the branches (closer to the trunk since the youngest needles are at the tips) and also on the lowermost branches, since these needles are also being shaded a bit by the spruce's own growth above that point. To differentiate shedding needles from those that contracted an infectious disease, look for fine black spots growing out of the dying needles before they fall off. If these spore structures are present, that may suggest that either of the fungal needle diseases spruce is prone to is at least partially responsible for some of the needle shed.
Copper-based fungicide sprays can be broad-spectrum enough to impact a variety of plant pathogens, but no fungicide is curative for existing infections. Only preventative applications made well before symptoms manifest can work, though even then they don't always work well, which is one of the reasons we typically don't recommend fungicide use as a matter of course. Additionally, copper-based products tend to have strict limits in how many applications can be made per year so you don't build-up toxic levels of copper in the soil, so make sure the product you've chosen either doesn't have this restriction or that you stay within its recommended limits. Copper excesses in the soil can't be remedied and may cause root damage directly or can injure the beneficial soil microbes that help roots function.
Unless you see clear indications of disease, we suggest you cease fungicide use for now and just keep an eye on the tree's irrigation needs going forward. (Even if this is one of the needle cast diseases, you won't be able to treat it well, if at all, with fungicide sprays long-term, so you aren't losing much by suspending treatment now.) Feel the soil around six inches deep in its root zone and water well only when it's becoming somewhat dry to the touch at that depth. While Colorado spruce is one of the most drought-tolerant of the spruces grown in Maryland, it can still benefit from periodic watering when our weather stays too dry or hot. The only native spruces in our area grow only in our higher-elevation western-MD mountains, where the soil is much more free-draining and the climate cooler (day and night) and less humid; unfortunately not conditions we can emulate in our suburban landscapes.
Miri
While needle cast diseases can be quite common on spruce (particularly Colorado blue spruce) in our region, this appears to be mainly normal needle shed as the plant ages. It might exacerbated by any shade or root competition the tree is experiencing due to nearby mature trees, and/or due to periods of drought during summer since spruce are not well-suited to our growing conditions in the mid-Atlantic, despite how popular they seem to stay in local horticulture. (Even though you mention the nearest tree is forty feet away, its roots are still growing throughout that area and competing to some degree with anything growing in the same space.)
All evergreens do shed some of their oldest foliage/needles each year, often in autumn, and spruce needles can turn yellow or brown before falling. The oldest foliage will be on the innermost portions of the branches (closer to the trunk since the youngest needles are at the tips) and also on the lowermost branches, since these needles are also being shaded a bit by the spruce's own growth above that point. To differentiate shedding needles from those that contracted an infectious disease, look for fine black spots growing out of the dying needles before they fall off. If these spore structures are present, that may suggest that either of the fungal needle diseases spruce is prone to is at least partially responsible for some of the needle shed.
Copper-based fungicide sprays can be broad-spectrum enough to impact a variety of plant pathogens, but no fungicide is curative for existing infections. Only preventative applications made well before symptoms manifest can work, though even then they don't always work well, which is one of the reasons we typically don't recommend fungicide use as a matter of course. Additionally, copper-based products tend to have strict limits in how many applications can be made per year so you don't build-up toxic levels of copper in the soil, so make sure the product you've chosen either doesn't have this restriction or that you stay within its recommended limits. Copper excesses in the soil can't be remedied and may cause root damage directly or can injure the beneficial soil microbes that help roots function.
Unless you see clear indications of disease, we suggest you cease fungicide use for now and just keep an eye on the tree's irrigation needs going forward. (Even if this is one of the needle cast diseases, you won't be able to treat it well, if at all, with fungicide sprays long-term, so you aren't losing much by suspending treatment now.) Feel the soil around six inches deep in its root zone and water well only when it's becoming somewhat dry to the touch at that depth. While Colorado spruce is one of the most drought-tolerant of the spruces grown in Maryland, it can still benefit from periodic watering when our weather stays too dry or hot. The only native spruces in our area grow only in our higher-elevation western-MD mountains, where the soil is much more free-draining and the climate cooler (day and night) and less humid; unfortunately not conditions we can emulate in our suburban landscapes.
Miri
Thank you very much for your quick and expert opinion. I will check out the needles more carefully but I didn’t notice any spots before. I will also check the soil moisture content especially during the growing season. I did water the tree most days during the hottest part of the summer using a 2.5 gallon bucket though maybe that’s not enough? I also fertilized using a slow release 10-10-10 every couple of months but it certainly didn’t help the tree’s health.
Take care and thanks for all your help!
BTW. this tree was planted in the same spot as another blue spruce was but it was removed when we had the house rebuilt. That tree never had this problem and it was well over 20 years old but it never grew beyond 7’ tall. That tree was surrounded by very large trees that were also taken down due to the construction work so it got very little light which might explain its lack of growth.
Steve
Steve
Mobile E-mail
On Oct 25, 2022, at 3:27 PM, Ask Extension <<personal data hidden>> wrote:
You're welcome.
Trees and shrubs usually do not need fertilizer, and adding nutrients when not needed could potentially stress roots (partially through interfering with moisture absorption) and may force growth the plant is not equipped to maintain. Application of a slow-release fertilizer every couple of months sounds like much more than the plant would need or be able to make use of, so we suggest you not fertilize at all going forward (it shouldn't need it, especially if any nearby lawn is being fertilized yearly).
It's hard to say if 2.5 gallons was enough, but for a ten-foot tree, probably not. You could feel the soil at that six-inch depth hours after or the day after watering and see if the moisture has percolated that far; if not, a greater volume of water during irrigation may be needed.
Miri
Trees and shrubs usually do not need fertilizer, and adding nutrients when not needed could potentially stress roots (partially through interfering with moisture absorption) and may force growth the plant is not equipped to maintain. Application of a slow-release fertilizer every couple of months sounds like much more than the plant would need or be able to make use of, so we suggest you not fertilize at all going forward (it shouldn't need it, especially if any nearby lawn is being fertilized yearly).
It's hard to say if 2.5 gallons was enough, but for a ten-foot tree, probably not. You could feel the soil at that six-inch depth hours after or the day after watering and see if the moisture has percolated that far; if not, a greater volume of water during irrigation may be needed.
Miri
Got it! Thanks Miri.
Got it! Thanks Miri.
