If you have an orange, grapefruit, lime or lemon tree anywhere in Florida, you've probably heard the words "citrus greening." It's the most serious disease of citrus in the state, and backyard trees are not immune. Greening doesn't mean you can never grow citrus again. It does mean you need to know what to look for, what else it might be and what your realistic options are.
What is citrus greening?
Citrus greening, also called huanglongbing or HLB, is a bacterial disease. The bacteria live in the tree's phloem, the tissue that carries sugars from the leaves to the roots and fruit. It's spread by the Asian citrus psyllid, a tiny insect that feeds on tender new leaves, or "flush." Once a tree is infected, there is no cure. UF/IFAS considers the disease widespread wherever citrus grows in Florida, so assume psyllids and greening are in your neighborhood.
Signs of citrus greening
- Blotchy mottle. This is the most telling leaf symptom: irregular patches of yellow and green that don't match on both sides of the center vein.
- Yellow shoots. One branch or sector of the tree turns yellow while the rest stays green, and the yellowing spreads over time.
- Small, upright leaves and twig dieback. The canopy thins out and looks sparse.
- Poor fruit. Fruit may be small, lopsided, stay green at the bottom end, taste bitter or sour and drop early. Seeds inside may be small and dark.
- Root decline. Greening damages the roots, which is why infected trees often wilt and decline even with good care.
Greening or just hungry? Try the midrib test
Many things turn citrus leaves yellow, especially on Florida's sandy or alkaline soils. Nutrient deficiencies of zinc, manganese, iron or magnesium are common. Here's a simple way to start sorting it out:
Fold a yellow leaf in half along the center vein. If the yellow pattern is symmetrical, mirroring on both halves, a nutrient deficiency is the more likely cause. If it's asymmetrical, with blotches that don't match, greening is more likely.
The midrib test is a clue, not a diagnosis. Root rot, overwatering, leafminer damage and other diseases can mimic parts of greening. Only a laboratory test can confirm HLB. Your county UF/IFAS Extension office can explain how to submit a sample.
What to do if your tree has greening
Option 1: Remove the tree
UF/IFAS recommends removing infected trees, because they serve as a source of bacteria that psyllids can carry to healthy trees. If your tree is in steep decline, with heavy dieback and little useful fruit, removal and replanting is often the most practical choice.
Option 2: Manage it and keep it producing
If the tree is still producing and you'd like to keep it, good care can slow the decline, although it won't cure the disease:
- Feed steadily. Use a citrus fertilizer with micronutrients, applied in smaller, more frequent doses during the growing season. Our guide on fertilizing fruit trees in Florida covers timing and technique.
- Protect the roots. Avoid overwatering, keep mulch off the trunk and keep the root flare exposed.
- Control psyllids on new flush. Check tender new growth for tiny psyllids, their nymphs and their waxy white secretions. Horticultural oils and other products labeled for psyllids on home citrus can help. Always follow the label, especially on fruit you plan to eat.
Replanting citrus? Do it the smart way
- Buy certified trees. In Florida, citrus nursery trees must be produced under insect-proof screen and certified. Buy only from a registered Florida nursery.
- Don't move citrus around. Florida is under citrus quarantines, so don't bring citrus plants or cuttings in from elsewhere or carry them out of state, and don't share budwood from a neighbor's tree.
- Diversify. Many Florida yards are adding fruit trees that greening doesn't affect, such as mango, starfruit, mulberry and guava, alongside or instead of citrus. Our regional guides for Tampa Bay and Central Florida have ideas.
Other citrus problems that look similar
Before you make a big decision, rule out the look-alikes:
- Nutrient deficiencies cause symmetrical yellowing and respond to the right fertilizer.
- Root rot from soggy soil causes yellowing, wilting and thinning canopy.
- Scale insects and sooty mold weaken trees and blacken leaves. See our guide to scale, mealybugs and sooty mold.
- Citrus leafminer leaves silvery, winding trails and curled new leaves, but rarely kills established trees.
Get a professional opinion
I'm Tony, a botanist and arborist, and I run Giardino Fresco with my family at 2264 SW 22nd Ave in Miami. If your citrus is yellowing or declining and you're not sure why, a trained eye can help you decide whether to treat, manage or replace it. Our Sick Tree Diagnosis Visit covers pests, disease, nutrition and watering anywhere in Miami-Dade, and you'll get a written care plan with clear next steps. If a lab test is needed to confirm greening, I'll tell you how to get one.
Worried about your citrus? Book your Sick Tree Diagnosis Visit and call or text 786-774-2125 to schedule. You can also browse all our Tree Care Services.
