Tree problems · Disease
Rhizosphaera needle cast: signs and what to do
Rhizosphaera needle cast is a tree disease, often seen on colorado blue spruce, black hills and white spruce, Norway spruce. Look for: needles that turn brown or purplish, then drop.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Disease
- Colorado blue spruce (the most often hit)
- Black Hills and white spruce
- Norway spruce (less often)
- Rarely other conifers
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
0 of 6 signs ticked. Ticks stay in this browser only.
Season
Infection is mainly in spring, when new needles come out and the weather is wet. Brown needles often do not show until the following months, and black dots show the next spring.
How it spreads
Spores come out of the black dots on old infected needles and spread in splashing rain and wind to the new needles. Humid, damp conditions and crowded trees make the disease worse.
Where it is found
Rhizosphaera needle cast is found in many parts of the United States where spruces are planted, especially in damp or humid areas. Check your state official map; ranges change.
Official sources
What to do
- 1
Look at the lower branches for brown or purplish needles and bare patches. Take photos and keep a few needles in a bag.
- 2
Ask your county extension office or a plant clinic to confirm the cause before you treat. A look-alike disease called stigmina needle cast needs a different approach.
- 3
Prune out badly infected branches in dry weather, when the tree is dormant if possible, to improve airflow.
- 4
Keep the area around the tree open and water at the base in dry spells, not on the needles.
- 5
If the tree is badly affected, ask a certified arborist or your extension office whether a fungicide timed to new growth makes sense.
- 6
Expect that infected needles will not recover. New growth can fill in over time if the tree stays healthy.
Safety first: do not climb, do not cut near power lines and do not use a chainsaw on storm-loaded wood. Call the utility for downed lines and 911 if anyone is in danger.
Prevention
Do not plant blue spruce in damp, crowded or poorly aired spots. Space trees so air can move between them, and keep trees healthy because stress makes infection more likely. Ask a nursery about spruces that suit your area. A mix of species also lowers the risk of losing a whole row.
When to call a pro
Call a certified arborist if a spruce has lost many needles from the bottom up, has bare branches, or you are not sure if it is a disease or a mite. Pruning high branches or removing a large spruce is work for a trained and insured crew.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: Colorado blue spruce (the most often hit), Black Hills and white spruce, Norway spruce (less often), Rarely other conifers.
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain rhizosphaera needle cast to a customer
Be honest that fungicide protects new needles but cannot cure old ones, and that treatment may be needed for a couple of years. Confirm the cause before selling a spray, because look-alikes respond differently. Tell owners that the tree may look thin for some time, and give them a clear, written plan.
Send this page to the customer after your visit so they can read the signs in plain words. See also selling plant health care and the job photo checklist.
Questions
What is Rhizosphaera needle cast?
It is a fungus disease of spruce that makes needles turn brown or purple and fall off, starting on the lower branches and moving up.
Which spruces get it most?
Colorado blue spruce is the most often hit. Other spruces can get it too, and Norway spruce is less often affected.
Will the tree die?
Usually not quickly. Repeated needle loss over several years can weaken the tree and kill lower branches. Healthy trees often hold on.
Will the bare branches grow back?
Infected needles will not recover. New needles can fill in some bare patches over time if the tree stays healthy, but dead branches will not regrow.
Do I need a fungicide?
Only in bad cases, and only after the cause is confirmed. Timing matters: sprays go on as new needles come out. Ask your extension office and follow the label.
How can I tell it from other problems?
Mites, drought, other needle diseases and canker diseases can look alike. Tiny black dots in rows on the needles help, but a plant clinic can confirm.
What should I do with fallen needles?
Many sources advise raking them up and throwing them away, not composting, to cut down on spores.
Can Lirevon diagnose rhizosphaera needle cast on my tree?
No. Lirevon is a remote marketing team for tree service companies and does not do tree work. This page is general information, not a diagnosis. A certified arborist or your county extension office can confirm what is wrong with your tree.
How do I find a good local pro for this?
Search Google Maps for certified arborists or tree services near you, read their reviews and ask for proof of insurance. Get two or three written quotes. Our guide on how to hire a tree service lists the questions to ask.
Related tree problems
- Cytospora canker (Disease)
- Cankers (Disease)
- Road salt damage (Other damage)
- Spider mites (Insect)
- Bagworms (Insect)
- Drought Stress (Other damage)