From towering Eastern White Pines to the drought-tolerant Ponderosa and fast-growing Loblolly, pine trees come in many varieties and are found across a wide range of climates. Despite their diversity, most species of pine are vulnerable to a similar set of diseases that can cause everything from needle browning to sudden death.
Whether you’re tending to ornamental pines in your yard or managing a forest stand, it’s important to recognize the signs of common pine tree diseases and know how to respond. In many cases, early detection and proper care can slow or stop the spread.
Pine tree sickness
These whitebark pine seedlings are growing in the Coeur d’Alene nursery in Idaho. They’re part of a program that screens whitebark pines for natural resistance to blister rust fungus, a nonnative disease.
Blister rust has killed off as many as 90% of whitebark pines in some areas. American Forests is responsible for half of all rust-resistant whitebarks that have been planted in the U.S. and Canada.
Here are some of the most common diseases that affect pine trees, what causes them, and how to treat or prevent them.
For other common problems, see our article on maple tree diseases and problems with oak trees.
1. Pine Wilt
Pine Wilt Nematodes! What the hey are they?
This information is very useful for individuals who have/ care for exotic pines.
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- Cause: A parasitic nematode (Bursaphelenchus xylophilus) spread by pine sawyer beetles.
- Symptoms: Sudden needle discoloration (from green to tan), wilting, and rapid dieback—often killing trees within weeks.
- Prevention & Treatment: Remove and destroy infected trees to prevent spread. Systemic insecticides can help control the beetles that carry the nematodes.
Pine wilt is especially problematic in non-native pines such as Scotch pine, though some native species are affected too. It primarily targets mature trees and is most common in the central and southern U.S.
2. Diplodia Tip Blight
The major disease of Austrian Pine is Diplodia tip blight, which initially infests the stems and needles at the tips of branches, often starting with the lowermost branches. Most of the time in Ohio, this kills the Austrian Pine in about 15 years to the point that I think about them as short term 15 year trees.
- Cause: A fungal infection caused by Diplodia sapinea.
- Symptoms: New shoots and needles turn brown and die, often still attached. Resin-soaked cankers may form on twigs or branches.
- Prevention & Treatment: Prune and destroy infected parts of the tree. Apply fungicides in early spring when new growth emerges and keep trees healthy with good cultural practices.
This disease often affects Austrian, Ponderosa, and red pines. It tends to strike older trees and is more severe when trees are stressed by drought or injury.
3. Dothistroma Needle Blight
Some evergreen coniferous trees have struggled in recent years in Ohio with foliar fungal infections. Colorado blue spruce is native to mountainous regions of western North America but has been commonly planted in Ohio as an ornamental tree. Several fungal diseases, like Rhizosphaera and Stigmina needlecast and Cytospora and Phomopsis canker commonly cause needle discoloration, premature needle loss, and branch dieback, usually starting from the lower branches and progressing upwards. Because of these disease issues, Colorado blue spruce is no longer recommended for planting in Ohio.
Eastern white pine’s native range in Ohio is mainly the northeastern quarter of the state. “White pine needle damage” is a collective term for several fungal diseases of the needles such as brown spot needle blight, Dothistroma needle blight, and Diplodia tip blight, which cause general discoloration and premature needle loss, and can lead to tree decline and death. All the fungi above listed are native, but because Ohio has seen increased rainfall during the growing season over the last decade or so, these fungi can more readily spread and infect their host plants. Some cultural or fungicide treatments may slow symptom progression. Certified arborists and foresters can provide recommendations for yard tree situations and woodland situations, respectively.
- Cause: A fungal disease caused by Dothistroma septosporum.
- Symptoms: Dark green needles develop reddish-brown bands, then turn brown and drop prematurely.
- Prevention & Treatment: Improve air circulation, remove fallen needles, and apply fungicides during the growing season.
This disease is especially damaging to lodgepole and ponderosa pines and is common in moist, humid areas. Severe cases can cause complete defoliation over several years.
4. Lophodermium Needle Cast
Austrian pine (center) ravaged by fungus disease during the many rainy months this year. It has distinctive platey, deeply-furrowed bark, two long needles, and broadly ovoid cones.
In the United States, this pine is vulnerable to various disease organisms, including Dothistroma Needle Blight (caused by Dothistroma pini), Lophodermium Needle Cast (caused by Lophodermium pinastrii), and Diplodia Tip Blight (caused by Diplodia pinea). As a result, this pine often suffers from premature needle-drop and branch die-back, especially after it reaches 30 years of age. Many trees die prematurely as a result.
- Cause: Caused by the fungus Lophodermium seditiosum.
- Symptoms: Yellowing of second-year needles, black fungal fruiting bodies on dead needles, and early needle drop.
- Prevention & Treatment: Rake and destroy fallen needles. Apply preventive fungicides in spring, especially in nurseries or young tree plantations.
This disease is generally cosmetic on mature trees but can stunt young ones. It thrives in wet environments with dense foliage and poor airflow.
5. White Pine Blister Rust
White Pine Blister Rust is a species of rust fungus that affects white pine trees. It can be pruned out if caught in the early stages.
- Cause: A fungal pathogen called Cronartium ribicola, which requires both pine and Ribes (currant/gooseberry) plants to complete its life cycle.
- Symptoms: Swollen cankers on branches, resin oozing from infection sites, and yellowing needles.
- Prevention & Treatment: Remove Ribes plants from nearby areas. Prune out infected branches early and plant rust-resistant cultivars when possible.
This disease mainly affects eastern and western white pines and can be fatal over time. It is particularly prevalent in the northeastern U.S. and Pacific Northwest.
6. Fusiform Rust
Fusiform rust is arguably the worst disease of southern pine. Cankers are prime spots for stem breakage. Fortunately, we have a very good breeding program and most selections now are rust resistant.
- Cause: A fungal disease caused by Cronartium quercuum f.sp. fusiforme.
- Symptoms: Spindle-shaped galls on stems and branches, which can girdle and kill portions of the tree.
- Prevention & Treatment: Plant resistant pine species, remove infected seedlings, and manage alternate hosts like oak trees.
Fusiform rust is common in the southeastern United States and is especially problematic in slash and loblolly pine plantations. It spreads through airborne spores.
7. Annosus Root Rot
All southern pines are susceptible to annosus root rot, but loblolly and slash pine are most severely affected.
- Cause: Caused by the fungus Heterobasidion annosum, which enters through fresh stump surfaces.
- Symptoms: Thinning crowns, dieback, stunted growth, and large conks (mushroom-like structures) near the tree base.
- Prevention & Treatment: Avoid thinning pines during high-risk periods (typically warm, moist months). Treat fresh stumps with borate-based fungicides after cutting.
This disease is one of the most economically damaging forest diseases in the U.S. It affects many southern yellow pines and spreads quickly through root contact.
Pine tree dying
Pine trees are hardy and iconic, but like all trees, they’re susceptible to a range of diseases—many of which can spread quickly and cause serious damage if left unchecked. From fungal infections like Dothistroma needle blight to pests that transmit pine wilt, knowing what to look for is the first step in protecting your trees.
In many cases, early intervention can make a big difference. Pruning affected branches, improving air circulation, applying preventative treatments, and maintaining overall tree health can go a long way toward keeping your pine trees thriving.
If you suspect your tree is sick and you’re unsure of the cause, it’s always best to consult with a certified arborist or local extension office. They can help with diagnosis and recommend appropriate next steps—whether it’s treatment, removal, or simply keeping an eye on things.
Let us know in the comments below if you’ve dealt with any of these pine tree diseases or have questions about what might be affecting your tree.
