Sunset Maple Bark Splitting: Normal or Problem?

Bark splitting on your 3-year-old Sunset maple is likely growth-related cracking, not a disease or insect problem. Sunset maple has thin bark and fast growth, making it prone to vertical fissures, especially on the south/southwest side (frost cracks or sunscald).

When It's Normal

• Foliage is green, full, healthy.
• Splits are vertical, not oozing, no sawdust/frass.
• Tree is vigorous.

Protective Care

• Mulch ring (3 ft, 2–3 inches deep) prevents mower/string trimmer damage.
• White trunk wrap (paper or plastic) Nov–Mar prevents winter sunscald on young trees.
• Do not paint/seal cracks—traps moisture, promotes decay.

Monitor for Borers

Stressed trees attract borers. If you see:

• Sawdust at base or in cracks
• D-shaped or round exit holes
• Loose bark with galleries underneath

→ Spray trunk with bifenthrin or permethrin in spring (preventive) or when activity seen.

Your tree sounds healthy. The splits are cosmetic and will become characteristic bark texture with age.