Laurel Wilt Disease: A Serious Threat to Trees in the Laurel Family

Laurel Wilt Disease: A Serious Threat to Trees in the Laurel Family

Laurel wilt is a fast-moving, deadly disease that is spreading through forests and landscapes across the southeastern United States. It poses a major threat to native trees in the Lauraceae (laurel) family, including redbay, sassafras, swampbay, and even avocado. Understanding what causes laurel wilt and how it spreads is critical for protecting susceptible trees and ecosystems.

What Causes Laurel Wilt?

Laurel wilt is caused by a fungus known as Raffaelea lauricola. This fungus is introduced into trees by the redbay ambrosia beetle (Xyleborus glabratus), a small, invasive insect originally from Asia. The beetle carries the fungus into the tree’s vascular system when it bores into the wood to create galleries for reproduction. Once inside, the fungus spreads rapidly, blocking the movement of water within the tree. This internal disruption causes infected trees to wilt and die, often within weeks.

How It Spreads

The redbay ambrosia beetle is the primary vector, but it isn’t the only way laurel wilt moves across the landscape. The fungus can also spread through root grafts between nearby trees. Infected firewood, logs, and wood debris transported by people can unintentionally carry the beetle and fungus to new areas. Birds may also play a role in spreading infected beetles.

Recognizing the Symptoms

Early signs of laurel wilt can be subtle, but the disease progresses quickly. Trees typically exhibit sudden wilting and leaf discoloration, turning reddish or purplish before they fall. Infected trees often die rapidly—sometimes in as little as four to six weeks after symptoms appear. Beneath the bark, dark staining in the sapwood may be visible, often in streaks, which can be a key diagnostic clue. Beetle entry holes and frass (a sawdust-like byproduct) may also be visible on the trunk.

Trees at Risk

Laurel wilt affects many members of the laurel family, and native species in the southeastern U.S. are particularly vulnerable. Redbay (Persea borbonia) and swampbay (Persea palustris) are among the most heavily impacted, but sassafras (Sassafras albidum) and cultivated avocado trees (Persea americana) are also susceptible. The disease has caused extensive mortality in forests, natural areas, and urban landscapes.

Where It’s Found

First discovered in Georgia in 2002, laurel wilt has spread rapidly across the southeastern U.S. It is now found in at least 12 states, from Texas to North Carolina, and continues to expand its range. The warm, humid climate of the Gulf Coast region has allowed the beetle and fungus to thrive, leading to widespread tree losses.

What Can Be Done?

Unfortunately, there is no cure for laurel wilt once a tree is infected. Prevention and early detection are key. Avoid moving firewood or wood debris from areas where laurel wilt is known to occur. If you live in a region where the disease is present, monitor susceptible trees for signs of infection. Infected trees should be removed promptly and destroyed, ideally by chipping or burning the wood on site.

Some research is ongoing to explore potential treatments and resistant plant varieties, but for now, the focus remains on containment and mitigation.

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