If you grow avocados in Miami-Dade, laurel wilt is the disease you need to know about. It has killed native redbay and swampbay trees across the Southeast and has cost South Florida avocado growers a large number of trees since it reached the region's groves. The hard truth is that once a tree is badly infected, it can't be saved. The good news is that knowing the early signs, and acting fast, can protect the rest of your yard and your neighbors' trees.
Here's what every Miami avocado owner should know.
What is laurel wilt?
Laurel wilt is caused by a fungus, Raffaelea lauricola, that attacks trees in the laurel family (Lauraceae). Avocado (Persea americana) is in that family, along with redbay, swampbay and silkbay.
The fungus is carried by tiny ambrosia beetles. The first one identified was the redbay ambrosia beetle, an invasive insect from Asia, but in avocado groves several other ambrosia beetles have also been found carrying the fungus. A beetle bores into the trunk or a branch, the fungus gets into the tree's water-conducting tissue (the sapwood), and the tree reacts by plugging its own plumbing. Water can no longer move up to the leaves, and the tree wilts and dies, sometimes within weeks to a few months.
No avocado variety is known to be immune. Florida types, Hass-style hybrids and West Indian types can all be infected.
Signs of laurel wilt on an avocado tree
Laurel wilt is easy to confuse with drought or root problems at first, so look for this combination of signs:
- Sudden wilting. Leaves droop and lose their shine, often starting on one branch or one section of the canopy, then spreading.
- Brown leaves that stay put. Leaves turn reddish-brown or brown and often stay hanging on the tree for a long time instead of dropping. A tree that looks "scorched" but holds its dead leaves is a red flag.
- Dark streaks in the wood. If you carefully peel back a little bark on an affected branch, infected sapwood shows dark brown to black streaks or discoloration. Healthy sapwood is pale.
- Beetle holes and "toothpicks." Look on the trunk and larger branches for tiny round entry holes, sometimes with thin strands of compressed sawdust sticking out like little toothpicks. Not every infected tree shows these clearly, but when you see them with wilting, take it seriously.
Things that can look like laurel wilt
Not every wilting avocado has laurel wilt. In South Florida we also see:
- Phytophthora root rot, which hits avocados in poorly drained or flooded soil. Trees decline more gradually, with small, pale leaves and dieback.
- Flooding and waterlogging after heavy summer rains or storms. Avocados hate wet feet, and roots can die quickly in standing water.
- Drought stress on young trees that haven't rooted in yet.
- Cold damage after a rare freeze, which browns leaves on the exposed side of the tree.
Because the right response is so different, removing a tree versus fixing drainage or watering, it's worth getting a proper diagnosis before you make any big decisions. The UF/IFAS Extension office in Miami-Dade and university plant diagnostic labs can test wood samples for the laurel wilt fungus.
What to do if you suspect laurel wilt
1. Act quickly
The disease moves fast, and infected trees attract more beetles, which can then carry the fungus to nearby avocados. Don't wait to "see if it gets better."
2. Get it confirmed
Have a trained arborist look at the tree and, if needed, send a wood sample to a diagnostic lab. The dark streaking in the sapwood is a strong clue, but a lab test is the only way to be sure.
3. Remove and destroy infected trees
Research by UF/IFAS shows that prompt removal of infected trees is one of the most important steps for protecting neighboring trees. That means cutting the tree down and disposing of the wood properly, typically by chipping it on site or following local guidance on disposal. Nearby avocados can also share the disease through root grafts, so ask about stump and root management too.
4. Don't move the wood
Never take firewood, logs or untreated mulch from a laurel wilt tree to another property. Moving infested wood is one of the main ways the beetles and fungus travel to new areas.
5. Protect the healthy trees
In commercial groves, systemic fungicide treatments (such as propiconazole applied by trunk injection) have been used to protect healthy, high-value trees. These treatments are preventive, not a cure, they need to be repeated, and they should be applied by a professional. For most home growers, the best protection is keeping trees healthy, catching problems early and removing infected trees quickly.
Keeping your avocado trees strong
Stressed trees are more attractive to many wood-boring beetles. Give your avocados the basics:
- Excellent drainage. Plant on a slight mound if your yard holds water, and never let water pool around the trunk.
- Consistent watering for young trees, then deep, less frequent watering once established.
- Balanced nutrition with micronutrients, since our alkaline limestone soils can lock up iron, manganese and zinc.
- Clean pruning with sharp tools, and no unnecessary wounds to the trunk from string trimmers and mowers.
- Regular walk-arounds. Look up into the canopy and check the trunk every couple of weeks. Early detection matters more than anything else with this disease.
Replanting after laurel wilt
Losing an avocado is hard, especially one that's fed the family for years. If you've lost a tree, talk with an arborist about timing and placement before replanting, and make sure the old wood and stump have been dealt with properly. When you're ready, start with healthy, grafted nursery stock. Our grafted avocado trees, including Florida Hass and Choquette, are grown right here in Miami.
Worried about your avocado? Let's check it now
I'm Tony, a botanist and arborist, and my family runs Giardino Fresco at 2264 SW 22nd Ave in Miami. With our $80 Sick Tree Diagnosis Visit, I'll come to your home anywhere in Miami-Dade, inspect your avocado for pests, disease, root and watering problems, and leave you a written care plan with clear next steps. If anything needs treatment or removal, it's quoted separately so you know the cost first. You can also browse all of our tree care services.
Don't wait on a wilting avocado. Book your Sick Tree Diagnosis Visit today, then call or text 786-774-2125 to schedule.
