The Gumbo Limbo tree, Bursera simaruba, is a fast-growing native species known for its resilience and unique appearance. It is widely recognized by its nickname, the “Tourist Tree,” due to its smooth, reddish-brown bark that peels away in thin, papery strips, much like sunburnt skin. While generally robust and wind-resistant, its health can be compromised by specific insects, diseases, and environmental factors.
Pests That Target Gumbo Limbo
A primary concern is the Gumbo Limbo Spiraling Whitefly, Aleurodicus rugioperculatus, a sucking insect that feeds on plant sap from the underside of leaves. Infestation is identified by white, waxy material on the lower leaf surface, often deposited in spiral patterns around the female’s eggs. The whitefly excretes honeydew, a sticky, sugary liquid that fosters the growth of black sooty mold on leaves and surrounding surfaces.
While sooty mold does not infect the tree, heavy accumulation blocks sunlight, hindering photosynthesis and leading to leaf drop and decline. Another sap-feeding pest is the soft scale insect, which colonizes twigs and leaf petioles and also produces honeydew. For small trees, a strong stream of water can dislodge whiteflies, or horticultural oils and insecticidal soaps can be applied to smother the insects.
Disease Concerns
Root rot is a common problem, primarily caused by fungal pathogens like Phytophthora or Fusarium species, which proliferate in poorly drained or waterlogged soils. Symptoms include yellowing leaves, wilting, and overall decline, which may be mistaken for drought stress.
Ganoderma butt rot, caused by the fungus Ganoderma zonatum, leads to wood decay at the tree’s base, hollowing out the trunk. This fungal infection is often fatal and is characterized by large, woody, shelf-like structures called conks near the soil line. Leaf spot diseases, often fungal, can also occur during wet periods, appearing as small lesions that may cause premature defoliation. Proper drainage and avoiding wounds to the trunk are the best preventative measures.
Vulnerability to Environmental Stress
As a tropical species, the Gumbo Limbo is sensitive to cold temperatures, which limits its range. While mature trees tolerate brief dips, temperatures sustained below 50°F (10°C) can cause leaf defoliation. Extended exposure near freezing can result in bark splitting and permanent dieback of branches, weakening the tree and making it susceptible to opportunistic pests and diseases.
Water stress is also problematic. Although the tree is drought-tolerant once established and sheds leaves during dry periods, overwatering is a common issue. This occurs particularly where poor soil drainage or compaction traps moisture around the root zone. While the tree tolerates a wide variety of soils, nutrient deficiencies in poor urban sands can lead to chlorosis or stunted growth.
Structural and Maintenance Issues
The Gumbo Limbo is known for wind resistance, but it has soft, lightweight wood, and smaller limbs are prone to breakage during strong storms. This vulnerability is exacerbated by poor architectural structure, such as weak branch unions, or “crotches.” These narrow unions, where multiple limbs emerge at a narrow angle, are structurally unsound and prone to splitting under wind load or weight.
Improper pruning techniques also create issues. Leaving stubs or “topping” the tree creates large wounds that struggle to seal and provide entry points for decay fungi like Ganoderma. When propagated from large cuttings, the resulting tree often develops numerous, poorly attached sprouts that require corrective pruning. Additionally, large surface roots can become a maintenance concern in urban areas, potentially lifting sidewalks or damaging foundations.