Avocados are such a joy to grow. Care for them the right way, and they’ll reward you with rich, creamy fruit that’s perfect for brunch!
But if the growing conditions aren’t quite right, avocado trees can face a few issues.
Fungal diseases (like root rot) are usually the biggest concern among avocado trees.
However, you should also watch out for pests, nutrient deficiencies, and environmental stress.
These problems can cause damage to the fruit and stunt the tree’s growth.
Here’s a guide to common avocado tree problems and what you can do to address them.
Diseases | Pests | Nutrient Deficiencies | Environmental Stress | Prevention Tips
What Does a Sick Avocado Tree Look Like?
Sick avocado trees usually show signs through their leaves, fruit, or roots. You may also notice less new growth than usual.
If something looks off, here’s a quick guide to help you identify what’s going on:
| SYMPTOMS | WHAT IT COULD BE |
|---|---|
| Avocado leaves turning yellow, curling, or falling | Nutrient deficiency, overwatering, or root rot |
| Avocado leaves turning brown at the tips and edges | Chloride toxicity, fungal issues (like anthracnose), heat stress, or nutrient deficiency |
| Bark lesions that ooze liquid | Bacterial canker or physical damage |
| Branches suddenly wilting or dying | Nutrient deficiency, root rot, or verticillium wilt |
| Discoloured spots on avocado leaves and fruit | Anthracnose, cercospora leaf spot, or sunblotch viroid |
| Premature fruit drop and puncture marks on the fruit | Fruit-spotting bugs or fruit flies |
Keep in mind that the table above is just a starting point.
Below, we’ll explain various avocado problems in more detail to help you figure out the exact cause!
Avocado Tree Diseases
Avocado diseases are often caused by bacteria or fungi, which thrive in damp conditions.
To avoid infections, it’s important to keep the canopy airy and dry.
You can do this by pruning your avocado tree regularly to let in sunlight and improve air flow.
(TIP: If you have several trees or you need extra help with pruning, consider hiring a gardening specialist to tackle the task!)
You can also use natural methods to prevent disease. Some common options are:
- Copper-based fungicides or bactericides
- ½ tbsp neem oil + a few drops of dish soap + 1L of water
- 1 tbsp baking soda + a few drops of dish soap + 1L of water
Spray the foliage thoroughly every 1–2 weeks. Do this while the fruit is developing, and continue until harvest.
For severe infections, it’s best to talk to a specialist. And always make sure that the treatment you apply is approved for use on avocados!
Anthracnose
| Signs | Yellow spots on the leaves and stems, which gradually darken |
| Treatment | Prune infected parts; use a copper-based fungicide for prevention |
Anthracnose is a fungal disease that starts on the avocado leaves and eventually affects the fruit.
It usually starts as yellow spots on the leaves of avocado trees, which grow into large, brown or black patches.
If the infection spreads, the tree may begin losing plenty of leaves. The fungus can also reach the fruit and cause it to rot after harvest.
Because of this, anthracnose is considered one of the most serious avocado tree diseases.
To treat anthracnose, cut off any infected parts of the tree. Then, spray the remaining foliage and branches with a copper-based fungicide.
After harvest, you can also spray the fruit with a fungicide that contains imidazole or fludioxonil.
Avocado sunblotch viroid (ASBVd)
| Signs | Sunken yellow, white, or red streaks or blotches on the fruit |
| Treatment | No cure; infected trees should be removed |
Avocado sunblotch viroid (ASBVd) spreads through infected roots or stems, often during grafting.
It mostly affects the fruit but can impact the entire tree, including the leaves and roots.
As the infection progresses, the avocado tree may produce fewer and poorer-quality fruit.
The good news is that this viroid is rare in Australia, thanks to strict quarantine rules!
To be safe, only purchase avocado trees from a garden centre accredited by the Avocado Nursery Voluntary Accreditation Scheme (ANVAS).
Bacterial canker
| Signs | Sunken, dark lesions on the trunk or branches that may ooze fluid |
| Treatment | Usually not needed for mature trees |
Bacterial canker is caused by the bacterium Xanthomonas campestris and is fairly common in avocado trees.
It’s considered a minor disease, so treatment isn’t usually necessary, particularly for mature trees. Just keep up with regular care to keep your tree healthy.
However, young avocado trees are more at risk as they’re still getting established.
To manage the disease, you can prune off affected branches and use a copper-based bactericide.
Cercospora leaf spot
| Signs | Dark brown spots on avocado leaves and fruit |
| Treatment | Prune affected parts; use a copper-based fungicide for prevention |
In avocado trees, cercospora leaf spot is caused by the fungus Pseudocercospora purpurea.
Symptoms include brown spots on the leaves and small spots or cracks on the fruit’s skin.
Cercospora leaf spot is not as persistent as anthracnose. Still, it can cause significant fruit loss if not managed properly.
If you notice any infected parts, prune them immediately to prevent the infection from spreading.
Then, spray the foliage and branches with a copper-based fungicide as fruits are forming.
Phytophthora root rot
| Signs | Avocado tree leaves turning yellow or pale green; sparse foliage |
| Treatment | Consult a specialist |
Phytophthora root rot is probably the most destructive disease affecting avocado trees in Australia and worldwide.
It’s caused by the fungus-like pathogen Phytophthora cinnamomi, which can lie dormant in the soil for years.
Soggy, poorly draining soil can encourage P. cinnamomi to grow.
To manage Phytophthora root rot, early detection is key!
Avocado tree leaves may turn purple-red, then become yellow or pale green before wilting. You might also notice fewer leaves and little to no new growth.
If you’re unsure, carefully dig around the base of the tree. Look closely at the feeder roots — tiny, hair-like parts near the surface of the ground.
If the tree’s roots are infected, they will appear brown or black and smell rotten. In this case, stop watering your avocado tree right away.
You can use a phosphonate fungicide to treat Phytophthora root rot. However, it’s best to consult a specialist, as correct timing and application are critical.
Stem-end rot
| Signs | Dark brown or black rot at the stem end of the avocado fruit |
| Treatment | Use fungicides during fruit set and after harvest |
Stem-end rot is a post-harvest disease that appears on the avocado fruit as it ripens.
Several species of fungi that live on the branches and leaves can cause stem-end rot.
However, the infection doesn’t show any visible signs until after harvest.
It begins as a dark brown or black rot at the stem end and gradually spreads down the fruit.
To prevent stem-end rot, use a copper-based fungicide as the fruit develops, up until harvest.
You can also use a fungicide with imidazole or fludioxonil as a post-harvest treatment.
Verticillium wilt
| Signs | Sudden wilting of one or more branches; brown leaves that stay on the tree |
| Treatment | Prune the affected parts |
Verticillium wilt is caused by the soil-borne fungus Verticillium dahliae. This pathogen can enter the tree through the roots.
It’s commonly found in soil where host plants like tomatoes and potatoes were previously planted.
In infected avocado trees, he leaves also turn brown and die, but often stay on the tree for several months.
As the disease worsens, one or several branches may suddenly wilt.
Treatment isn’t usually needed for verticillium wilt. Just cut back on watering and prune the affected branches to help the avocado tree recover.
Avocado Tree Pests
Avocado trees can be susceptible to pests, especially if they’re grown near other plants that attract bugs.
Some pests go after the avocado fruit, while others target the leaves, which can slow down the tree’s growth.
Fruit-damaging pests
| Signs | Fruit drop; puncture marks and discoloured patches on the avocado fruit |
| Treatment | Neem oil solution and fly traps |
Pests like fruit-spotting bugs and fruit flies can damage the avocado fruit and make it inedible. They can also cause early fruit drop.
Fruit-spotting bugs pierce the fruit’s skin and release saliva inside. They can leave wood-like deposits in the flesh, which deforms the fruit.
Fruit flies are another major concern. They lay eggs inside the avocado fruit, which leads to rot.
To manage these pests, spray the foliage with a solution of ½ tbsp neem oil, 1L of water, and a few drops of dish soap.
You can also buy a fly trap from a garden supply store, or make your own.
For a DIY option, grab a plastic bottle and poke a few holes around the upper half. Pour in a mixture of fruit juice, some sugar, and a little brewer’s yeast.
Hang a couple of these near your avocado tree or on the branches. Replace the solution weekly as it loses potency over time.
Collect any fallen fruits right away to stop the bugs and flies from breeding. Seal the fruits in a rubbish bag and dispose separately — do not use them for compost.
Lastly, only use chemical insecticides if the infestation is severe, as they can also harm beneficial insects.
Leaf-damaging pests
| Signs | Damaged, falling leaves; crawling bugs on branches |
| Treatment | Neem oil solution |
Some pests target the avocado tree leaves instead of the fruit. If they multiply, they can cause severe defoliation.
This can lead to poor yield and stunted growth over time.
Check the branches and the undersides of the leaves for common avocado tree pests like:
- Thrips
- Aphids
- Mealybugs
- Caterpillars
- Spider mites
- Scale insects
Prune any heavily infested parts. Then, spray the leaves (including the undersides) with a solution of ½ tbsp neem oil, 1L of water, and a few drops of dish soap.
Do this weekly until the pests are gone.
Avocado Tree Nutrient Deficiencies
Avocado plants need a lot of nutrients to thrive. Signs of nutrient deficiencies include discoloured leaves, drooping branches, and stunted growth.
The tree may also stop fruiting completely!
Each nutrient deficiency shows up in different ways, so it’s helpful to know what to look for:
CALCIUM DEFICIENCY: New leaves growing deformed or bending downwards
MAGNESIUM DEFICIENCY: Yellowing between leaf veins, with the veins themselves remaining green
NITROGEN DEFICIENCY: Pale green or yellowing leaves, leaf drop, and stunted growth
PHOSPHORUS DEFICIENCY: Slow growth, weak-looking tree, and twig dieback
POTASSIUM DEFICIENCY: Leaf tip burns, brownish-red spots between leaf veins, and weak stems
To address nutrient deficiencies, feed your avocado tree with a balanced, slow-release NPK fertiliser.
Another option is to add well-rotted compost and other organic material around the base of the avocado tree.
Do this 3 times every year: during flowering, during fruit development, and after the main harvest season.
You can also use foliar sprays that contain micronutrients like boron, copper, iron, and zinc.
BONUS TIP: Grow avocado companion plants like legumes to help return nutrients to the soil!
Avocado Trees and Environmental Stress
Factors like extreme temperatures, incorrect watering, and poor soil can affect how well avocado plants grow.
Extreme temperatures
Avocado trees can be sensitive to both extreme cold and heat. They grow best in temperatures between 16°C and 29°C.
Cold stress can cause avocado leaves to wilt, turn brown, and fall off.
You might also see dark patches on small branches, while larger ones can split or lose bark.
If you’re in a colder area, try wrapping your avocado tree in a frost cloth to protect it from cold snaps.
Alternatively, consider growing avocado varieties like Bacon and Fuerte. These can handle low temperatures better.
On the flip side, high temperatures can be just as damaging to avocados.
Heat stress can cause leaf scorch — when the avocado leaves’ edges turn brown and brittle. Early fruit drop is another symptom.
To prevent heat stress, plant your avocado tree in a spot that gets afternoon shade. Also, water your tree more during hot weather.
Incorrect watering
Getting watering right for avocados can be tricky. Too little or too much can cause problems!
Underwatered avocado trees may show signs similar to heat stress.
The leaves may turn brown, curl, or wilt. Over time, the tree may also start producing fewer leaves than usual.
To check if it’s time to water, stick your finger about 5cm into the soil. If it feels dry, give the tree a good drink.
On the other hand, overwatering can also cause serious problems.
The leaves of an overwatered avocado tree may turn pale green or yellow. They may also appear limp and eventually start falling off.
Excessive moisture can also harm the avocado roots. Be sure to check if the roots are dark, mushy, and foul-smelling, which are signs of root rot.
If you spot these, stop watering immediately. Then, trim the infected parts of the root and monitor your tree closely.
Soil salinity
Saline soil — often found in arid or semi-arid areas — is harmful to avocados.
Excess salt in the soil makes it harder for avocado trees to absorb nutrients and water.
It can also lead to chloride toxicity. Signs include leaf burn, which starts at the tips and edges, gradually moving inwards.
You might also see round, dead spots between the leaf veins. The affected leaves may also fall off over time.
It’s best to check for soil salinity before growing an avocado tree. Use an electrical conductivity (EC) meter, available at most garden supply stores.
Collect soil samples and follow the instructions on the packaging for accurate results.
If the soil turns out to be saline, plant your avocado in a raised garden bed, about 1m deep and 3m wide. Be sure to use a high-quality, well-draining soil.
Tips to Prevent Avocado Problems
Only buy your avocado tree from a garden centre accredited by the Avocado Nursery Voluntary Accreditation Scheme (ANVAS) to make sure it’s disease-free.
You can also ask about trees that were grafted using pest- or disease-resistant rootstocks. These are specifically bred to handle common issues.
Make sure to grow your avocado tree in the right conditions. It needs at least 6–8 hours of direct sunlight daily and well-draining soil.
Remember, avocados have a sensitive root system that doesn’t do well in soggy ground.
Proper watering matters, too. Only water at the base of the avocado tree, and avoid getting the branches and leaves wet.
When it’s time to harvest, pick the avocados during dry weather. Moisture on the fruit can lead to fungal problems like anthracnose or stem-end rot.
Lastly, keep your tree in shape with regular pruning. Remove dead and crossing branches to open up the canopy.
This allows sunlight to reach the inner branches and foliage, keeping your avocado tree healthy.
FAQs About Avocado Tree Issues
Still wondering what’s troubling your avocado tree? Keep reading to learn more!
How do you treat avocado tree disease in Australia?
First, it’s crucial to figure out what disease you’re dealing with, as symptoms can be similar.
For mild infections, prune the affected parts using clean, sharp tools. Bag up the parts you cut and dispose of them separately.
Do not compost them to avoid spreading the disease.
Next, spray the remaining branches and leaves with a copper-based bactericide or fungicide. Aim to do this every 1–2 weeks.
However, do not overdo it, as copper-based treatments can sometimes drive away beneficial insects.
For post-harvest fruit rot, look for a treatment with imidazole or fludioxonil. But make sure it’s approved in Australia for use on avocados.
If the disease is advanced (especially with root rot), it may be better to remove the tree.
When in doubt, we strongly advise you to consult a specialist for the most accurate advice.
Do avocado trees lose their leaves?
Avocados are evergreen trees, so they do not naturally lose their leaves.
If the leaves are falling off, it could be a sign of disease, pests, or nutrient deficiency.
Environmental stress (such as overly cold or hot weather) and incorrect watering could also be the cause.
Why is my avocado tree not producing fruit?
If your avocado is taking a while to fruit, consider the tree’s age.
Seed-grown trees take about 10–15 years before fruiting. Meanwhile, grafted trees start to produce fruit within 3–4 years.
Poor pollination can also delay fruit production. On top of that, the tree’s growing conditions and overall health also play a role.
Luckily, there are many ways to encourage your avocado tree to produce fruit.
First, enhance pollination by planting another avocado tree nearby.
Healthy trees are also more likely to bear fruit. Make sure your avocado tree gets adequate sunlight and that it’s growing in well-draining soil.
