Citrus Tree Care in Florida: Common Diseases and Prevention

Protecting Florida's Citrus Trees

Florida and citrus have been synonymous for over a century, but the state's beloved orange, grapefruit, and lemon trees are under unprecedented pressure from devastating diseases. Whether you have a single backyard tree or a small grove, understanding the threats and taking proactive steps can mean the difference between a healthy harvest and total tree loss.

The warm, humid climate that makes Florida ideal for citrus also creates favorable conditions for the pathogens and insect vectors that spread disease. Homeowners across the state — from Jacksonville to Miami, Tampa to the Keys — need to stay vigilant.

Citrus Greening (Huanglongbing / HLB)

Citrus greening is the most destructive citrus disease worldwide and has devastated Florida's commercial citrus industry since its detection in 2005. It is caused by the bacterium Candidatus Liberibacter asiaticus and spread by the Asian citrus psyllid, a tiny flying insect.

Symptoms to watch for:

• Asymmetric yellowing of leaves (blotchy mottling that does not mirror on both sides of the leaf midrib)
• Small, lopsided fruit that remains green at the bottom even when ripe
• Bitter, off-flavor juice from affected fruit
• Twig dieback and thinning canopy over time
• Leaf drop and overall tree decline

There is currently no cure for citrus greening. Infected trees gradually decline over several years. Management focuses on controlling the psyllid vector and maintaining tree nutrition.

Citrus Canker

Citrus canker is a bacterial disease caused by Xanthomonas citri that produces raised, corky lesions on leaves, stems, and fruit. While it does not kill trees, it causes premature fruit drop, reduces fruit quality, and weakens trees over time.

Look for:

• Raised, brown, crater-like lesions surrounded by a yellow halo on leaves and fruit
• Oily appearance on the underside of young lesions
• Premature leaf and fruit drop during wet weather
• Lesions that are often associated with wind-driven rain and storm damage

Melanose and Greasy Spot

These common fungal diseases are less severe but still impact tree health:

• Melanose causes small, raised, dark brown spots on leaves and fruit, mainly on new growth
• Greasy spot produces yellow-brown blisters on the undersides of leaves, leading to defoliation

Prevention and Care Strategies

Protecting your Florida citrus requires a multi-pronged approach:

• Control Asian citrus psyllid with systemic insecticides or horticultural oils — this is the single most important step against citrus greening
• Apply copper-based fungicides during the growing season to manage canker, melanose, and greasy spot
• Maintain proper nutrition with citrus-specific fertilizers applied three to four times per year; stressed trees are more susceptible
• Prune properly to improve air circulation and remove dead or diseased wood — check our pruning calendar for timing
• Water deeply but infrequently to encourage strong root systems; avoid overhead irrigation that spreads bacterial diseases
• Remove fallen fruit and debris to reduce fungal inoculum in the landscape

Visit your Florida state guide for region-specific care recommendations and local extension resources.

When to Call a Professional

If you notice asymmetric leaf yellowing, lopsided fruit, or rapid decline, contact an ISA Certified Arborist immediately. Early intervention with nutritional programs can sometimes extend the productive life of greening-affected trees by several years.

Frequently Asked Questions

Q: Can I cure citrus greening in my backyard tree? A: Unfortunately, there is no cure for citrus greening. However, aggressive nutritional programs, psyllid control, and proper care can keep mildly infected trees productive for years. Severely infected trees should be removed to reduce the psyllid population and protect neighboring citrus.

Q: Should I plant new citrus trees in Florida? A: Yes, but choose disease-resistant or tolerant varieties when available and purchase only from certified nurseries that screen for greening. Protect young trees with systemic insecticides from the day they are planted.

Q: How do I know if my tree has citrus canker or citrus greening? A: Canker produces distinct raised, crater-like lesions with yellow halos, mainly on leaves and fruit surfaces. Greening causes asymmetric blotchy yellowing of leaves and misshapen fruit. Use our diagnosis tool to compare symptoms and get guidance.

Q: Is it safe to eat fruit from a tree with citrus greening? A: Fruit from greening-affected trees is safe to eat, though it may taste bitter or off-flavor. The bacterium does not affect human health.