Burl on the trunkA burl is an abnormal growth usually found on the trunk. In general it doesn't hurt the tree or indicate weakness.
Slime fluxSometimes trees "bleed" something other than sap. If the stain is extensive, call a Certified Arborist.
Lightning scarCall a professional if you see a long scar like this on your tree.
Fusiform cankerFusiform canker is a fungus on pine trees that can cause them to break. Call a professional if you see one.
BulgeThis tree is trying to strengthen a weakened area with extra wood. If you see this on your tree, there will most likely be a fusiform canker on the other side.
Pitch tubesPine trees will try to drown attacking beetles with pitch tubes made of sap. Pitch tubes can be different colors (rose on left, amber on right). If you see these on your tree trunk, it usually means the tree will have to be removed.
Woodpecker damageThese trees are showing the work of a pileated woodpecker (left) and a yellow-bellied sapsucker (right). The pileated woodpecker is going after insects in decayed or dead wood; this tree is probably hazardous. The sapsucker is opening a hole for sap in live wood; the tree is probably okay.
Trunk cavityThe hole created by an old pruning cut (like this one) sometimes allows decay to enter the trunk. The cavity could be large even if the hole is small. This tree required an "aerial" inspection to assess the cavity.
Fungus on upper trunkWhen fungus grows where two trunks meet, there is usually weakness below the surface. This situation requires immediate professional attention.
Zone 3: The trunk
The trunk holds up the tree and supports the massive weight of its branches. Inspect the trunk thoroughly.
- Cavities can be dangerous, depending on their size, where they're located on the tree, and how deep they are. If there is a cavity above eye level, a "climbing" inspection may be needed to find out how deep it is and if there is decay.
- Cracks and splits in the trunk are extremely dangerous. If there is a crack or split in the trunk, the entire tree could fall or break apart at any time.
- Missing bark (or areas where bark is falling off) usually signals a dead section. Look for places on the tree’s trunk where there is no bark, the bark is falling off, or the bark is discolored. Missing bark can also indicate a surface wound, infection, or a fungus attack.
- A long streak of missing bark coming down the tree usually means the tree was struck by lightning. It's possible that a tree can recover from this, but if the leaves turn brown after several weeks, the tree has died.
- When ants and beetles attack, they leave very fine, light-colored sawdust (“frass”) that is easy to see. Ants cutting into decayed wood leave coarse shavings. Pine bark beetles attacking a pine tree leave “pitch tubes” that resemble marble-sized balls of light-colored sap.
- Trees with 2 or more trunks sometimes crack and split where the trunks connect. Strong connections appear as a “U” shape; weak connections resemble a tight “V” shape. Sometimes a tree adds layers of wood over the trunk connection to strengthen a crack. After a windstorm, look at the connection in the tree where the trunks meet. Use binoculars if the connection is high up. If there is a lightly colored line that contrasts to the natural dark bark color, you are probably looking at a fresh crack. The tree may be in the process of splitting apart. Consider this situation an emergency.
If you see any of the above conditions in your tree, call a Certified Arborist immediately to determine if your tree is stable enough to leave standing or whether it should be removed.