Laurel Wilt
Harringtonia lauricola
A fast-killing fungal wilt of trees and shrubs in the laurel family, carried by an invasive wood-boring beetle. The fungus plugs the water-conducting tissue, so an infected tree wilts and dies within weeks to months, and it has devastated wild redbay and threatens avocado, sassafras, bay, and related plants across the Southeast.
🔎 How to spot it
The earliest sign is sudden wilting: green leaves on a branch droop and turn from olive-grey to reddish or purplish-brown but cling to the tree, and the symptom spreads from one branch through the whole crown. Beneath the bark the sapwood shows dark black or brown streaking, and tiny entry holes from the beetle, sometimes with thin toothpick-like tubes of compacted sawdust pushed out, mark where it bored in. The dead brown leaves staying on the tree are characteristic.
🥀 Damage it causes
The fungus blocks the water-conducting vessels, so the tree wilts and dies rapidly, often within a few weeks to a few months of the first symptoms, and the infection can spread to nearby host trees. Wild redbay has been killed across large areas, and the disease is a serious threat to commercial and dooryard avocado as well as to sassafras, bay laurel, and other native laurels. There is essentially no recovery for an infected tree.
🔬 What causes it
Laurel wilt is caused by the fungus Harringtonia lauricola, formerly known as Raffaelea lauricola, which is introduced into the wood by the invasive redbay ambrosia beetle and related ambrosia beetles as they bore into the trunk and limbs. The beetles carry the fungus as a food crop, and once inside they and the fungus spread through the tree; beetle flight and movement of infested wood carry it to new areas.
🛡️ Prevent it
Do not move untreated firewood or logs from laurel-family trees, which is a main way the beetle and fungus reach new places, and chip or burn infested wood on site rather than transporting it. Watch susceptible trees, especially in and near areas where the disease occurs, and report sudden wilt of redbay, sassafras, bay, or avocado to agricultural authorities. Promptly remove and destroy infected trees to reduce local beetle buildup.
🧯 If it is already here
There is no cure for an infected tree, so destroy it promptly to limit the beetles and fungus, and avoid moving the wood. High-value avocado and landscape trees can be protected before infection with professionally applied systemic fungicide injections, which must be repeated and are not a rescue once a tree is wilting. Area-wide management focuses on sanitation, not curing diseased trees.
💡 Good to know
Laurel wilt spreads through both beetle flight and the careless movement of infested firewood, so the simple rule of not transporting laurel wood does real good. The clinging reddish-brown dead leaves and the black streaking in the sapwood, together with beetle entry holes, separate it from drought and other wilts. Avocado growers in affected regions treat it as a top threat and rely on preventive injections plus strict sanitation.
🌱 Plants it affects
4 plants in the library can be affected by this problem
For educational and informational purposes only. Disease management advice is general guidance drawn from university cooperative extension sources; always identify a problem positively and read and follow the label on any product before use, especially around food crops, children, and pets.