Blue Spruce trees die usually due to Cytospora canker disease. Blue Spruce needles may also turn brown due to Rhizosphaera/Stigmina needle cast disease. Blue Spruce is also affected by a variety of pests like White Pine Weevils and Bark Beetles.
Blue spruce is also called Green spruce, White spruce, Colorado Blue Spruce, or simply, Colorado Spruce.
The tree is a great addition to your landscaping plans thanks to its versatility. Blue Spruce can sustain harsh winds.
These trees, if planted in a row offer perfect privacy. The tree can grow from USDA zones 1 to 7. Let’s see what’s bothering your Blue spruce and how to fix it!
The Blue Spruce tree dies from the bottom up when it’s infected by Cytospera canker disease. This is a fungal disease.
Cytospora canker can be fatal to your Blue Spruce. Cytospora canker disease is most commonly seen on Colorado Blue Spruce.
Large, mature trees are affected by this disease as they are prone to drought conditions. Lower branches die and turn brown.
Cankers are characterized by the white resins that ooze out. Sunken cankers are seen which take years to girdle the tree.
Spruce tree dying from inside out?
Blue Spruce dies from the inside out if it’s infected by Cytospora canker disease. Dead/dying branches are seen randomly on the affected tree.
Needles of the affected Blue Spruce turn brown/purplish-brown and fall off the tree.
Cytospora canker can be deadly as it forms cankers in the trunk of the Blue Spruce tree. It could eventually kill your beautiful tree.
How do you treat Blue Spruce Cytospora Canker?
- There isn’t a cure for Cytospora canker. Keep your tree healthy to prevent the infection. I do not recommend fungicidal treatment as it’s ineffective anyway.
- Prune out and destroy the infected branches of your Blue Spruce to treat the plant. It takes time to get rid of the disease. Remember, prune only in the dry season.
- Cut at least 12-inches below the canker and disinfect the tools after working on an infected tree.
- Plant trees that are suited to your region. For example, growing Blue Spruce in Minnesota is not recommended.
- Weaker trees are easily affected by Cytospora canker disease. So, try to provide proper irrigation and soil to your Blue Spruce.
- Prune your trees only when the foliage is dry to prevent the spread of spores.
- Avoid causing wounds on your Blue Spruce. Lawn mowers and string trimmers wound the tree, so use them consciously.
Why are the lower branches of my Blue Spruce dying?
The lower branches of Blue Spruce die because of the top of the canopy shading the lower branches. Blue Spruce also dies from the bottom up if it’s suffering from Cytospora canker.
The top canopy of your Blue Spruce tree might need a trim.
If the issue is really due to the top canopy, the central and lower branches should die. These don’t get an adequate amount of sunlight.
You can use a tree pruner to prune off the top of the tree that’s causing this issue. Get professional help if needed.
I recommend canopy thinning to help your tree thrive. Canopy thinning should be done in a dormant period for the best results.
Why do Blue Spruce needles turn brown?
Blue Spruce needles turn brown due to Cytospora canker disease. Blue Spruce needles also turn brown when the tree is infected by Rhizosphaera needle cast. Stigmina needle cast disease also causes the same damage to the victim plant.
Rhizosphaera and Stigmina are both different types of fungi that can infect the Blue Spruce tree. Microscopic diagnosis is the only way to differentiate these diseases.
Send the samples of the affected tree to a nearby lab as soon as possible. Needles of the affected Blue Spruce turn yellow first and then brown.
Blue Spruce trees that are stressed from drought, poor planting practices, or other improper care practices are more prone to needle cast diseases.
Tip: Observe the affected tree’s needles using a magnifying glass and you’ll see tiny, black colored bead-like spores.
Can a Blue Spruce recover from needle cast?
Yes, an infected Blue Spruce can recover from needle cast disease if proper care is given. The tree will take a long time to recover.
Infected Blue Spruce takes up to 2 years to recover from needle cast disease. Severely infected trees take even more time to recover.
Blue Spruce needle cast treatment
Follow the below instructions to control needle cast disease on Blue Spruce trees.
- Make sure there’s enough air circulation around your Blue Spruce tree.
- Don’t plant Blue Spruce if it can’t take the regional conditions. Plant a tree that can thrive in your weather conditions.
- Don’t let the sprinklers spray your Blue Spruce’s needles. Wet needles lodge a variety of fungal pathogens.
- Fungicides that have Copper hydroxide/Mancozeb as the active ingredient help control Rhizosphaera infection. You can use the same fungicides to treat Stigmina needle cast too.
- Spray fungicides according to the instructions on the label.
When should a needle cast be treated?
You may want to spray fungicide on the infected Blue Spruce tree as soon as the new growth is seen.
I advise you to spray your Blue Spruce in the spring season. Apply once in 3-4 weeks for the best results. Make sure you cover all the needles well.
Blue Spruce dying from top down
Blue Spruce dies from top-down when the winter winds arrive. Blue Spruce also dies from top-down if there’s an infestation of White Pine Weevils or Bark Beetles
Winter Browning in Blue Spruce
Blue Spruce needles turn brown when they can’t stand the cold, winter winds. This is called winter burn.
The top part of the tree is usually affected as that’s where the winds hit the hardest. The top branches lose moisture and turn brown.
Help your tree retain moisture by mulching around it. Water your Blue Spruce adequately throughout the year to prevent the condition.
Pests on Blue Spruce
White Pine Weevils and Bark Beetles are the common pests of Blue Spruce. They attack the top canopy of the tree. The infected tree’s branches turn brown.
White Pine Weevils lay eggs in the branches in the spring. As soon as they hatch, the beetles start feeding on the needles.
Observe the tree closely. Do you see any sawdust or remnants of insects? If yes, there’s an infestation on the plant.
Bark beetles leave a yellowish-brown tint on tree crowns. They leave sawdust behind on the victim tree. Bark beetles target weak/old trees.
Cut off the affected branches and your Blue Spruce should recover by the next season.
Why is my Blue Spruce yellowing?
Blue Spruce turns yellow when it gets more water than needed. The roots get stressed when the Blue Spruce is overwatered. Blue Spruce also turns yellow in the initial stages of needle cast disease.
Blue Spruce needs adequate water to thrive but that doesn’t mean it can withstand waterlogged conditions.
What does overwatered Blue Spruce look like?
The needles of an overwatered Blue Spruce turn yellow. The new growth wilts and turns green or yellow if the tree is overwatered.
The leaves might look healthy, but they actually aren’t. They’ll become so brittle that they’ll break under pressure.
The ground around the Blue Spruce becomes soggy. Press the ground with your shoe at least a foot away from the tree.
Do you see excess water? Then the soil is definitely waterlogged.
How to treat an overwatered Blue Spruce?
- Stop watering immediately if you think the tree is sitting in waterlogged conditions.
- Water only when the soil becomes dry up to 2/3 inches.
- Treat the soil with a good fungicide to keep root rot at bay.
- Stop fertilizing the tree for a few months to let it recover.
Happy Growing 🙂