fallen avocado brown leavesAvocado leaves turning brown is never a good sight for any gardener as this can be a symptom of underlying problems. Find out what might be causing these brown spots on the leaves of your plant and how you can get rid of them in this comprehensive guide from our trusted avocado growers.

Why Do Avocado Leaves Turn Brown?

Sunburns, fungal diseases and edema are several possible reasons why your avocado leaves are turning an unsightly brown color all of a sudden. If you’re worried about this phenomenon, continue reading to discover the various causes.

– Sun Scorching

Avocado plants love to be put under warm, bright sunlight, but sometimes exposure to the sun might be too intense for your plant and it can develop brown spots on its leaves.

How can you tell whether the brown spots on avocado leaves are due to sun scorching and not any other cause? Check if the water and humidity requirements of the plant are being met. Brown spots due to sun scorching will also be accompanied by wilted and twisted leaves.

– Causes Behind Sunburn

Your avocado plant might get sunburned if it is placed near a southern-facing window that receives very harsh sunlight. When plants grown indoors are suddenly moved outdoors, they also get sun-scorched, leading to brown spots appearing on their leaves.

– What Can You Do?

Minimize exposure to the sun. Move the plant indoors and under indirect light by keeping your plant away from the harsh southern sunlight. Instead, place it in an eastern-facing window or protect it from the harsh midday sun by providing some sort of shade.

– Avocado Algal Leaf Spots

Often, avocado gardeners find the leaves of their plant turning brown as a result of a parasitic algae infection caused by Cephaleuros virescens. Brown spots on avocado tree leaves by this parasite occur because it affects the plant’s ability to perform photosynthesis.

These algal brown spots will appear first on the leaves and then move on to the stem. Yellowing of the underside of the leaves can also be seen alongside the brown spots.

– What Can You Do?

The algal leaf spot disease needs moisture to grow and spread. Learn how to treat it in this section.

  • Move your plant to a warm, sunny location.
  • Ensure proper drainage of the soil so that moisture retention can be avoided.
  • Cut off the infected brown-spotted leaves to stop the spread of the infection.

– Fungal Diseases

An avocado leaf with brown spots can also be a sign of fungal infections. There are three common fungal diseases that might be attacking your plant. Find out what they are and what type of brown patches they produce on the plant’s leaves below.

  1. Anthracnose: produces brown, sunburnt leaves with severe leaf drops.
  2. Downy Mildew: The leaves of your avocado plant will initially develop yellow patches with a greyish substance. These spots will then turn brown and, eventually, the leaf itself will fall off.
  3. Alternaria leaf blight: Starts with small brown specks in avocado leaves with a yellowish rim and progresses to rotting of the whole leaf.

– Factors Conducive To Fungal Infections

Here are some reasons your plant might have developed a fungal infection:

  • Overwatering the plant is a key factor in producing fungal rot. Only water the avocado plant once every two weeks.
  • Inadequate drainage of water from the soil and the pot will also cause fungal brown spots on avocado tree leaves. Make sure your pot has a drainage hole of the right size and that excess water is drained out of it every time you water.
  • A soil that is too tight and tends to retain moisture will also lead to root and plant rot. Use aerated soil that allows water to flow out of it.
  • Fungi love hot, humid and cramped conditions. Don’t put your plants too close together to ensure good air circulation. 

– What Can You Do?

A plant suffering from fungal rot should be immediately isolated from other plants to prevent spreading the infection around. Take sharp gardening shears or scissors and remove all infected leaves, along with the decayed parts of the stem. 

Sometimes when the infection has progressed a lot, you will also need to take out the entire plant along with its roots from the soil. Shake off the soil from the roots and inspect them carefully. Remove all the infected roots as well.

The tools used for cutting the infected parts of the plant should be cleaned and sterilized before using them on other plants. Our experts also suggest against using the dead leaves as compost.

Apply a strong and effective fungicide on the affected parts of the plant and repot the plant in fresh soil that is well-draining. Keep your avocado plant in a brightly lit place with good air circulation.

– Edema

Edema is another condition that leads to avocado leaves with dark spots. Along with brown spots, your leaves will also appear to have a crumbly, crust-like texture and corky, swollen veins.

The reason why this happens is when the soil has plenty of water to feed the roots but the surrounding humidity is too high to let all of it evaporate from the leaves. This leads to fluid build-up in the cells of your plant, leading to edema.

– What Can You Do?

Here are some steps you can do to ensure that your plant survives this condition.

  • Evaluate the drainage system of your pot. Create a bigger drainage hole at the bottom of the pot if necessary and remove the draining dish from the bottom as well.
  • Avocado plants love warm temperatures. Place them somewhere hot and bright with lesser humidity.
  • If the situation doesn’t seem to be improving, consider repotting the entire plant again.

Some Additional Reasons 

– Underwatering

Underwatering will also cause the leaves of your avocado plant to turn brown. This happens when roots are deprived of the needed moisture to keep the leaves cool enough to not get scorched. It is easy to find out if your avocado leaf problems are due to underwatering: simply check the top 4 inches of the soil. If it is dry, then your plant needs more water. 

– What Can You Do?

In this section, learn how to treat brown spots caused by underwatering.

  • Start deep watering your avocado plants. It mimics natural rainwater and will do wonders for your plant.
  • Water your plant abundantly every two to four weeks. Allow the excess water to drain out the drainage hole.
  • Always water the whole of the soil and not just the part at the base of your plant.
  • In hot and dry weather conditions, try mulching your plant. This involves using bark, leaves, newspaper, and other organic stuff to cover the top layer of soil in order to retain moisture in it.

– Harsh Cold And Frost

Avocado leaves browning is also caused by very low temperatures. You can tell that these brown spots are produced by the frost because they will appear curled as well.

– What Can You Do?

  • Do not keep your avocado plants in temperatures under 25 degrees Fahrenheit.
  • These plants can survive short periods of frost but for longer durations, consider moving them indoors. You can also wrap them up in sheets for the duration of the winter season.

– Nutrient Deficiency

The deficiency of certain nutrients in the soil or your fertilizer will also lead to avocado leaves turning brown. Learn more about this below.

– Iron Deficiency

  • Iron deficiency is most commonly present in soils with high pH.
  • It will produce brown spotting, leaf fall and leaf burn to your avocado plant.
  • Adding peat moss or any other organic compost to the soil is a great way to provide more iron to your plant.

– Nitrogen Deficiency

  • Nitrogen is soluble in water. The increased moisture content of your soil will lead to leaching out of this nutrient.
  • Symptoms of nitrogen deficiency include yellowing of the leaves along with the appearance of small dark brown spots.
  • Treat this condition by watering moderately and using nitrogen-rich fertilizers.

– Zinc Deficiency

  • Zinc deficiency is a more common phenomenon than other deficiencies even under normal circumstances.
  • The leaves of your plant will develop tiny brown spots and discoloration along the leaf margins. The leaf will also appear more deformed.
  • Using kelp extract or a foliar spray is our favorite trick to solve zinc deficiency.

Pests Might Also Be Responsible

If you see that your avocado leaves have brown spots and none of the above-mentioned conditions seem possible, then your plant is likely to be suffering from an insect infestation. That is why we regularly inspect our plants carefully each time we water them. Read on to find out what types of bugs might be responsible for the brown spots in your avocado leaves.

– Persia Mite

– Identification

Brown spots caused by Persia mites will appear to have webbing that will shine when light is thrown upon them. These brown spots will appear more on the bottom parts of lower leaves.

– Treatment

Find out how to treat brown spots on avocado leaves caused by Persia mites in this section. 

  • Keep the attacked plant away from other plants to prevent the spread of Persia mites from one pot to another.
  • Use a good insecticide and spray it on your avocado plant. Don’t forget to spray the bottom of the leaves as well.
  • You can also physically remove the bugs by using tissue paper or a high-pressure water hose. 

– Mealybugs

– Identification

Mealybugs are the pests most frequently associated with attacks on houseplants. A mealybug infestation will also lead to avocado leaves browning. 

– Treatment

Learn how to deal with mealybugs the right way below.

  • Although it is cumbersome, the best method is to use your hands to physically remove these bugs from your avocado plant.
  • You can also use a piece of cotton soaked in alcohol and apply it to the leaves. Alcohol can be substituted with an organic alternative that works just as well: neem oil.
  • Using a high-pressure hose to rid your plant of mealybugs also works. This process is not recommended for young plants as it can destroy their leaflets in the process.

– Avocado Thrips

– Identification

Want to find out which insect is responsible for avocado leaves brown tips? It might be none other than the Avocado thrip that attacks the tips and edges of the leaves and also attracts fungal spores. You will also notice black, leathery patches on the leaves in addition to the usual brown spots.

– Treatment

Avocado thrips are very easy to remove. Learn how to do so here.

  • Spray your plant with an insecticide that specifically kills Avocado thrips.
  • Introducing natural predators of these thrips to your plant is another clever alternative. This includes beetles and certain bugs that don’t harm the plant but get rid of the thrips.

Conclusion

fallen avocado leaves with dried spotsNow that you know the various ways your avocado leaf can turn brown in color, you can prevent this from happening or deal with it in the most appropriate way. Given below is a breakdown of the most important points you should keep in mind.

  • There are many reasons why your Avocado leaves might be turning brown in color.
  • Putting your plant under direct intense sunlight such as that of the midday sun or the southern-facing window will cause leaves to turn brown and wilt off. 
  • Always place the Avocado plant under either indirect sunlight or an eastern-facing window.
  • Improper drainage of the soil, overwatering the plant and high humidity levels will put your plant at a higher risk of algal and fungal infections.
  • In case of brown spots on the leaves due to fungal infections, remove all the infected leaves and other parts of the plant.
  • Spray your plant with a good fungicide. In severe fungal infections, you might have to repot the entire plant in fresh soil.
  • Sometimes, when the soil retains too much moisture and the surrounding humidity is also high, water might accumulate in the cells of your plant and cause the browning of its leaves. This condition is called edema.
  • Avocado plants should not be kept under temperatures lower than 25 degrees Fahrenheit. 
  • If brown discoloration or spotting of your leaves is due to the deficiency of any nutrient, then adding them to the soil will solve this problem immediately.

There’s no need to worry if you notice the leaves of your avocado plant browning. Just follow these tips and tricks to ensure a happy and healthy life for your plant!

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