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If you are fortunate enough to live in a tropical or subtropical region, zone 8 or above, then you may already be growing your own avocado trees. Once associated only with guacamole, avocados are all the rage these days, with their high nutrition content and versatility in many recipes.
Growing your own avocado trees can provide you with a seemingly endless supply of these delicious fruits. However, no plant is without its problems. If you were expecting an avocado tree laden with fruit, but instead have a sickly tree that rarely bears avocado fruits, this article may be for you.
Avocados are one of the most popular fruits around the world. With their creamy texture and rich flavor, it’s no wonder avocado toast, guacamole, and other avocado dishes have become so ubiquitous.
Beyond being delicious, avocados are also packed with nutrients like healthy fats, fiber, and vitamins C, E, K, and B-6. It’s no surprise so many people want to grow their own avocado plants and enjoy fresh avocados from their backyard.
However, avocado plants can be susceptible to rot, which can quickly kill the plant if left unchecked. So if you want your avocado plant to grow and thrive, it’s important to understand what causes rot and how to prevent it.
What Causes Rot in Avocado Plants?
There are a few key factors that can lead to rot in avocado plants:
Overwatering
Too much moisture around the roots is one of the most common triggers for root rot in avocado plants. Avocados prefer slightly drier soil and their feeder roots can easily become waterlogged if overwatered. This suffocates the roots and promotes fungal growth.
Poor Drainage
Even if you’re not overwatering, soil with poor drainage can still lead to excess moisture around the roots. Avocado plants need soil that drains well to prevent waterlogged conditions.
High Humidity
Humid environments also encourage fungal growth and rot. Greenhouses and other enclosed spaces may need extra ventilation and air circulation to prevent issues.
Cold Weather
Avocados evolved in tropical climates and are sensitive to cold. Exposure to frost or low temperatures can damage roots and cause rot.
Root Damage
Any injury to roots, whether from transplant stress, pests, or improper pruning, creates an entry point for rot-causing fungi. Healthy, undamaged roots are more resistant.
Nutrient Deficiencies
An avocado plant without proper nutrients can have weakened defenses and be more prone to diseases like root rot.
Preventing Rot in Avocado Plants
The good news is rot can be prevented through proper care and growing conditions:
Provide Good Drainage
Make sure avocado plants are in porous, well-draining soil or containers with drainage holes. Amend dense soils with compost or perlite to improve drainage.
Water Correctly
Water deeply but infrequently, letting the soil dry out between waterings. Check moisture levels before watering again.
Increase Air Circulation
Good air flow around the plant prevents humidity buildup and dried out the soil. Rotate containers or use fans to increase airflow.
Control Temperatures
Keep plants above 55°F/12°C and provide protection from frost or cold snaps. Move potted plants indoors or use row covers as needed.
Prune Carefully
Limit pruning to remove dead branches, being careful not to damage healthy roots. Sterilize pruners between cuts.
Practice Crop Rotation
For in-ground plants, rotate avocado trees to different areas of the garden each year to prevent diseases in the soil.
Add Organic Mulch
A 2-4 inch layer of mulch around the base insulates roots and retains moisture while still allowing airflow.
Provide Nutrients
Use a balanced organic fertilizer to ensure the plant gets key nutrients like nitrogen, phosphorus, and potassium.
Control Pests
Monitor for and treat sucking/chewing insects that can damage roots and create entry points for fungi.
Use Preventative Fungicides
Apply fungicidal drenches or supplements like phosphorus acid to protect healthy plants.
Treating Rot in Avocado Plants
If an avocado plant already shows signs of rot like yellowing leaves, poor growth, or dark mushy roots, take action to treat the issue:
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Remove the plant from its pot and wash off as much soil as possible from the roots to inspect the damage. Cut off any black or mushy roots.
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Repot in sterile, well-draining soil mix and prune back the damaged parts of the plant.
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Use a fungicide drench on the roots and lower trunk to kill pathogens. Repeat every 7-10 days.
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Increase air circulation and decrease watering frequency to encourage new healthy root growth.
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Add compost tea or beneficial microbes to boost recovery.
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Check soil pH and adjust if needed. Avocados thrive between 6.0-7.0 pH.
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Be patient! Recovery can take time as the plant grows new roots and regains vigor.
With quick action at the first sign of issues, many avocado plants can recover from rot. Key steps include removing damaged plant tissue, improving drainage, using fungicides, and allowing the roots to regrow in a healthier environment.
Frequently Asked Questions About Avocado Plant Rot
What are the first signs of rot in avocado plants?
Look for yellowing or browning leaves, slower growth, wilting despite watering, and dark roots with a foul odor. Damage often starts at the roots.
What is the best fungicide for avocado root rot?
Phosphorus acid fungicides are most effective for managing Phytophthora root rot in avocados. Other options include copper fungicides.
Should I cut off all the damaged roots?
Prune off any black or mushy roots completely. Damaged feeder roots can also be trimmed, but avoid over-pruning healthy roots.
How long does it take for an avocado plant to recover from root rot?
With proper treatment, avocado plants can often recover within a few months as new roots develop. However, recovery time depends on the extent of the original damage.
Can avocado root rot spread to other plants?
Yes, the fungus-like organism Phytophthora can spread from infected avocado roots to other plants through water runoff or shared soil/containers. Isolate sick plants.
Should I just pull out my avocado plant if it has root rot?
Not necessarily! If addressed early, many avocado plants can recover and regrow healthy roots after rot. But severely damaged plants may need to be discarded.
How can I revive my dying avocado plant?
Improving drainage, applying fungicide, removing dead tissue, adjusting pH and nutrients, and allowing time for new roots can help revive infected avocado plants.
Keep Your Avocado Plant Happy and Healthy
While avocado plants are susceptible to frustrating issues like root rot, the solutions are very manageable with good care.
By planting in suitable conditions, watering wisely, controlling humidity and temperatures, and using preventative fungicides, you can help your avocado plant avoid this common disease.
And if you catch it early, rot can often be successfully treated by pruning damaged tissue, improving drainage, using fungicides, and replenishing the soil.
With the right care techniques, your backyard avocado plant can live a long, productive life providing beautiful greenery and bountiful, nutritious fruit. The effort is well worth it for fresh guacamole!
About Phytophthora Root Rot
Phytophthora root rot is a fungal disease caused by the pathogen Phytophthora cinnamomi. This fungal disease affects avocado trees and thousands of other plants. It can be a particularly devastating disease in avocados and is estimated to result in about $50 million in crop loss in California each year.
Avocado root rot can affect trees of all sizes and ages. It mostly affects the feeder roots of avocado trees, causing them to become black, brittle, and unable to take up valuable nutrients and life sustaining water. Since these roots lie beneath the soil surface, this disease can severely infect a plant while going mostly unnoticed.
The first visible symptoms of root rot in avocado trees is light green to yellow, undersized foliage on infected plants. Leaves may also have brown, necrotic tips or margins. As the disease progresses, foliage will wilt and drop, exposing the fruit to sunscald. The upper branches of infected avocado trees will also die back.
Fruit production also declines in infected trees. They may bear small or sparse fruit at first, but eventually fruit production will stop altogether. This disease does usually result in the death of infected trees.
Treating Avocados with Root Rot
Excessive soil moisture and poor drainage are contributing factors of phytophthora root rot. It is most prevalent in sites that periodically floor or puddle up from bad drainage, low grade, or improper irrigation. Fungal spores can be spread by wind, but most often trees are infected from water runoff or infected scion or rootstock in grafting practices. The disease can also be spread by dirty gardening tools. Proper sanitation of gardening equipment and garden debris is always essential in controlling the spread of disease.