Spruce tree losing needles: what’s wrong? Easy revival tips


Healthy spruce trees, although they’re ‘evergreen’, do undergo browning and loss of needles – just look under any spruce and you’ll see a carpet of needles from past years. But this can make it all the more difficult to tell when your Picea is undergoing abnormal drop due to illness or otherwise.

Normally, a small proportion of spruce tree needles, on the most inner parts of branches, go brown and shed each autumn. Excessive or sudden inner needle drop is a sign of fungal disease, while needle loss at branch tips indicates tree stress from lack of water, winter injury or transplant shock.

It took a while to get to grips with this problem when I first started examining it on spruces. I hope to bring you a straightforward guide that brings together all my experience and book-learning.

Forestry websites often list many rare tree ailments. But which ones do everyday tree owners actually see? Which are the really common ones? Whether you have blue spruce, Norway spruce or any other Picea species, read on.

When do spruce trees drop their needles?

A little more on what’s normal.

Spruce trees typically exhibit browning and dropping of a proportion of their most inner needles every year, a process that normally begins in late summer and progresses through the autumn. New needles generally stay on the tree for around 3 years, though it can be as many as 10 years.

Compared to pine trees and some other conifers, the inner needle drop is a more gradual process of ‘thinning’.

Normal needle loss tends to be more marked on older trees which, by their considerable size, shade out their inner parts much more than young trees. In mature specimens, the lowest branches that sweep the ground can become mostly devoid of needles and appear quite brown, which will tempt owners to ‘limb up’ (prune them all off, leaving bare trunk at the bottom).

So in autumn, the needles that fall should, in the vast majority, be the ones that are shaded by other branches.

What you shouldn’t see is:

  • widespread visible bare patches – you should mostly have to lift up other branches to see bare spots.
  • browning and needle loss at the tips, where the newest needles are

If you’re seeing either of these, something has caused it. Read on to find out what.

spruce tree normal needle loss
This spruce exhibits normal thinning of needles on lower branches and the inner parts of branches that are higher up. Most needles are intact on the higher branches.

Spruce needle loss at branch tips

This shouldn’t happen, unless it’s the very lowest branches that are totally shaded by the upper foliage. It’s a sign of tree stress – the tree’s sacrificing its newest leaves (yes, needles are leaves) to maintain its survival during a difficult period.

Fortunately it’s usually easy enough to diagnose the cause – and the biggest clue is the time of year.

spruce needle loss browning tips drought
I took this photo in late summer. Note the needles are browning and falling off at the tips – this shouldn’t be happening. This spruce is stressed because of lack of water.

Winter injury – symptoms and causes

If you’re seeing browning at needle tips, or dropping needles on branch tips in mid/late winter or in spring, it indicates that the tree has had a difficult winter. This is common in evergreen trees such as spruces as they’re often used as windbreak trees or planted on exposed sites as ornamentals – I find that property owners often expect them to take whatever nature throws as them!

Also known as winter burn or winter desiccation, winter injury occurs when the needles have continues to lose moisture through the cold months (when leafless deciduous trees don’t), but the tree hasn’t been able to draw up enough water through the roots to replace it – resulting in dry, brittle outer branches, browning tips and eventual needle loss.

Spruces are particularly at risk when the ground freezes, when the roots really can’t draw up water.

Sometimes the needles can be green at the base, and gradually browning towards the tips, or you’ll get scattered brown and green needles throughout a branch.

You’ll often find that the browning and needle loss is not symmetrical –

  • The top of the tree, furthest from the roots, might be more affected than the bottom
  • The side that’s most exposed to the wind will be more affected
  • The side that faces your driveway or road might be most affected, due to spray from road salt – road salt increases the risk of winter injury

Does snow and frost damage spruce tree needles directly? Usually it won’t – dessication is the main problem. But occasionally, new needles at branch tips can be damaged by sudden cold snaps in the late springtime.

Winter injury – prevention and treatment

Once the needles have gone brown, they’ll eventually fall off. How can you prevent this happening year after year?

  • Water the tree in winter. This is the most important step. A 30-minute ground soak with a hose about once a month when the temperature is above freezing may be enough to prevent the recurrence of any winter burn the following year.
  • Erect a wind break for your tree or trees in winter, particularly while it’s young. Generally this means erecting some basic wooden posts and stretching some burlap or wind break netting between them.
  • Exercise caution in applying salt if the tree’s next to a driveway.
  • Anti-dessicant spray can be purchased – useful for smaller spruces
  • Make sure you have a layer of mulch underneath the tree – usually about 4 inches thick and about 5 feet in diameter (just don’t pile it up against the trunk – leave a 6-inch gap here to prevent trunk-rot). The mulch will insulate the roots from temperature drops, and help water to permeate through the ground.

Here’s a useful short video on evergreen winter injury from UNL Extension, which includes some advice about pruning as well.

https://youtu.be/3f0lTyxJgf0

Drought

Spruce trees have relatively shallow roots, and are often planted in yards with shallow or compacted soil. As such they can be sensitive to hot, dry weather in summer. This can result in gradual drying of the foliage – having first a brittle appearance and sometimes looking pale in color, then eventually turning brown and, when advanced, causing late summer needle drop.

Again the browning is usually apparent at the needle tips – I find that on close inspection, there is often a gradual browning visible along the length of some needles.

Spruce trees, particularly when young, need to be watered in warm, dry weather every one to two weeks. This not only prevents drought-related injury, but protects your tree from disease and ensures it achieves its growth potential. Give it a 30-minute soak. A sprinkler’s usually better than a hose – you want to water the area under the canopy.

Again, applying a 4-inch thick layer of mulch, such as wood chippings, will help ensure the roots can access to rain water and prevent them from dying out so quickly in the heat.

Recent planting

‘Transplant shock’ is a phenomenon not solely restricted to spruce, or even evergreen trees. When trees are moved or newly planted out of containers, it takes the roots some time to adjust to their new environment, particularly if they aren’t watered well early on.

This can result in an excessive browning and loss of needles near the tips. This is most pronounced in the first year, but can continue to lesser extents for up to 3 years.

Water spruces more frequently for the first 2 years (that means once a week during warm months, and once or twice a month in colder months) if they exhibit any signs of transplant shock.

Spruce needle loss at inner branches

I’ve explained that inner branch needle drop is normal in the fully shaded, inner parts. If you’ve got visible needle drop but the needles on the branch tips are spared, this is likely to be a fungal infection. There are three main types that attack spruce – cytospora canker, rhizosphaera needle cast and stigmina needle cast. I’ll outline the symptoms of all three, and then how to manage them at the end.

Cytospora canker

Various species of cytospora cause this fungal disease, which is widespread in spruce and pine trees over the whole world – particularly in the northern hemisphere. Trees that are stressed, damaged or exposed to drought are particularly susceptible.

It’s distinct in that it classically causes browning of lower branches one at a time (or in groups or two or three branches at a time), followed by complete needle drop, as a result of cankers forming on the bark – sunken grey or orange wounds on the trunk or near the base of the branch which seep whitish resin.

Look at the branches that have lost needles. If the bark along each branch looks healthy throughout, you likely don’t have cytospora canker.

To help you identify it and learn more, here’s the clearest video I’ve found, demonstrating how it affects blue spruces.

Rhizosphaera needle cast

Rhizosphaera kalkhoffii is another fungal pathogen that affects spruce trees worldwide. It’s a big problem for Christmas tree plantations. There’s considerable variation as to how it affects spruce through – Colorado blue spruce (Picea pungens) is particularly susceptible, as is Engelmann spruce (Picea engelmannii). Norway spruce (Picea abies) carries a fair degree of resistance.

A tree afflicted by the disease looks quite sick with thin foliage. Usually starting on the lower parts and then spreading upwards, the affected branches have browning (purplish in Blue spruce) needles along the branches – often except for the needles at the ends.

The needles usually fall off between early summer and autumn. On very close inspection of affected needles you might see rows of brown spots – the ‘fruiting bodies’ which contain fungal spores.

It won’t kill the tree, but will detract from its growth, vigor and appearance significantly if it continues throughout successive years.

In this useful video from Virginia Cooperative Extension, an infected blue spruce is demonstrated.

Stigmina needle cast

Stigmina needle cast causes almost identical similar symptoms to Rhizosphaera needle cast above. It’s caused by the fungus Stigmina lautii. I would say that the fruiting bodies on the needles are a little darker, and it’s certainly not as widespread as rhizosphaera, being recognised mostly in the United States.

Preventing and treating spruce fungal disease

Fungal diseases of spruce are not curable – they have to be controlled. Fortunately, this is achievable with a few hours of work a year.

It’s worth mentioning that arborists’ first weapon against spruce disease is by planting resistant varieties. While Norway spruce is quite resistant to rhizosphaera, serbian spruce and oriental spruce are two of the most trouble-free examples overall.

If your tree’s quite young, consider removing it and replanting with one of these – remember that fungal infections are incurable and that control is the only way you can go.

So how to control fungal disease in spruces. There’s no one easy way – but a combination of these will help.

  1. Prune off any infected limbs in dry weather. Since these are often lower down, you can remove all of the lowest branches, leaving a clean trunk, which will allow the tree to keep its pleasing symmetry. However, you’ll need to dispose of any infected branches in the trash, or burn them – don’t leave them lying on the ground, or the spores will reinfect other branches next year. If the branches show cankers (sunken wounds that seep with resin or have crystalized resin around them, with brown or dropping needles further out), make your cut several inches closer to the trunk.
  2. If you can, rake away and dispose of infected needles that have fallen from the tree, for the same reason.
  3. Keep the tree well watered (particularly important to prevent cytospora canker) – but getting foliage wet increases the risk of infection, so consider a soaker hose instead of a sprinkler – or at least water it in the morning, so the sun can dry the needles later in the day.
  4. Don’t crowd your spruce trees together. Plenty of airflow between the branches will help them to stay dry.
  5. Antifungal sprays can be tried, but many arborists think they don’t help. I’d recommend having an arborist look at your tree before embarking on any DIY treatment, though.

How do you revive spruce?

There are three simple ways to revive a spruce tree that isn’t thriving, all of which you can do yourself.

  1. Apply a proper layer of mulch, such as bark chippings, around the base of the tree. It should be 4 inches thick and about 5 feet in diameter, but keep the mulch from touching the trunk.
  2. Water it weekly during the summer and monthly in the cooler months, as long as the temperature is above freezing.
  3. Apply a ‘complete’ fertilizer to the roots, ideally a slow-release one such as Jobes Fertilizer Spikes for Evergreens.

And finally…

Will spruce needles or branches grow back?

As a general rule, once a spruce branch has dropped its needles, they will not regrow and the branch will eventually die. Go ahead and prune it off, but do so in dry weather to reduce the risk of disease entering the tree via the fresh cuts.

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