Why Is There Mold on my Avocado Seedlings? Here’s why!

When growing an avocado from seed, you may encounter white powdery growth on the seedlings and roots. The powdery mildew mold does pose an occasional risk because it can slow down the growth of the plant and make it rot.

If you are trying to grow avocado right from the seed, you will have to maintain the right conditions for it to germinate and stay healthy. 

The most common reason for the white mold on your avocado seedling is inadequate air and oxygen supply. The best way to treat this mold is by removing all the mold from the seed, spraying it with a fungicide, then putting it back in a jar with clean water, and make sure the seed is exposed to enough fresh air.

This fuzzy white power on the seedlings is a warning sign that your seeds are in danger. If this occurs, your seeds may not grow at the usual speed and may never turn into plants. However, there are several ways to manage its effects when they do occur. 

Mold on avocado seedling

Image by Animik.

Signs of white mold on avocado seedlings

White mold is a fungal disease that grows quickly in warm and wet conditions. On avocado seedlings, white mold can appear as a white or gray fuzzy coating on the surface of the seed, roots, and stems. 

It usually appears when there’s been too much rain or when the seeds have been watered heavily for too long. The newly grown roots from the avocado seedling may get covered in tiny white fungal growth. You will get to see this if your seedling is in a clear glass jar. 

In the beginning, stages of the fungus’ growth, you may see some cloudiness as the top layer of the water- just above where green naturally begin to show from the stem. 

Typically mild cases don’t require any treatment, but more severe ones will lead to root rot, and a plant might not recover from this damage if left untreated. Therefore, it is recommended to treat white mold as soon as you spot it. 

Why is my avocado seedling covered with white mold?

The main reason may be that the seed is way too wet, so the roots in the soil are rotting and suffocating in water. The seedling is also in a tray or a jar without drainage holes. Also, because this seedling is not getting enough light and sun if grown inside.

Another reason for the white mold is the overcrowding of the seeds. The seeds will not get adequate air supply and oxygen to grow. This remaining moisture without sufficient air will rot its puny little roots that can’t take up oxygen from air or nutrients from the soil due to lack of light. 

As a result, this will lead to an overgrowth of white mold fungi.

Stunning Zamioculcas zamiifolia 360...
Stunning Zamioculcas zamiifolia 360° View

How to get rid of white mold on avocado seedlings?

Powdery mildew is not as dangerous for the seeds and plants, but it needs proper treatment to maintain optimal health. It is ideal for treating the seedlings immediately when you notice the slightest signs of fungus and powdery mildew. 

If you notice there is a layer of white powder over the avocado roots, remove them immediately. This powder layer is responsible for delaying the growth of the seed. 

You may scratch off the fungus powder or remove the affected roots to be sure. You may also use a fungicide to eliminate the fungus and prevent it from spreading to other healthy parts of the seedling. Once removed, the seed will be back to the growing stage. 

Here are some easy steps for getting rid of white mold on avocado seedlings;

  • Take out the pit from the jar.
  • Put the seedling on a damp paper towel.
  • Wash the jar to ensure it is clean and free from remnants of fungus.
  • Fill the jar with clean water. 
  • Hold your seedling under running water and clean the cloudy fungus.
  • Make sure you remove fungus as gently as possible to prevent any damage to the roots and seedlings.
  • Now spray the seed with a natural fungicide (1 tbls. of baking soda, 1/2 tbls. of liquid soap in a gallon of water).
  • Also, pay attention to not to break the roots.
  • Finally, place the seed back in the jar with clean water.

Repeat this process for a couple of weeks if your seedling is in the jar for a long period of time. Otherwise, plant these seedlings into the soil or use larger jars when the roots are grown up to 1.5 times the diameter of the seed. 

Mold on avocado seedling

Image by Animik.

How to prevent this white mold?

Here are some proven ways you can prevent white mold growth on avocado seedlings. 

Providing the right temperature

Avocado seedlings grow well in warm temperatures. The ideal photosynthesis process occurs when they are kept between 75 and 82 degrees Fahrenheit. In case you are using heating mats, make sure the temperature is between these numbers to avoid under and overheating. 

Improving airflow

Another simple way to prevent mold growth on the seedlings is to improve the airflow around them. You may install a fan near the seedlings and let it run for at least 5-8 hours a day. In case you are growing the seedling in a tray that is covered, remove the top to increase the airflow. 

The improvement in airflow will prevent any fungal growth. Moreover, it will encourage the development of strong roots and stems. 

Avoid too much water and wet soil

One of the most common causes of fungus in plants is too much water. If the soil is overly wet, the roots will become delicate and lead to the rotting of seedlings. This will eventually stop the growth process and kill the plant. While planting, it is essential to maintain the optimal wetness to prevent the seed from drying. 

However, the water should not be too soggy to cause damage to the roots of the seedling. You may have to check the soil mix every day to determine how much water is required. If the soil is moist enough, skip watering it that day. 

Also, use trays and pots with drainage holes and a few stones as the last layer of soil to prevent soggy soil. Doing this prevents fuzzy mold in the seedlings. 

Lastly, you may improve your watering system with the one that allows you to water from the bottom of the container. This involves adding water from the bottom of the tray or letting the seedling soak moisture from the bottom. The delicate roots and stems will not be affected by water and remain healthy. 

Manage light

Light is important for the seeds to grow well, even when they do not need direct sunlight. Observe how much light the seedlings receive on a daily basis. This will help you assess how much light is required for the growth. 

Your newly grown avocado seedlings require light anywhere from 12 to 16 hours. It should be a good and strong light without any direct sunlight. Do not make the mistake of keeping covered trays in the sun as they will heat up and permanently damage the seedlings. 

Always use clean tools

Make sure you sterilize your trays, tools, and pots before using them. This will kill any pathogens and fungi that can be dangerous to your plants. You may use a solution of 10% bleach and 90% water to wash the trays, pots, shovels, and plant tags. 

After this, rinse them with warm water and leave them to dry before use. 

Repot the seedlings

Your seedling will outgrow the jars and trays. Once you observe the roots have grown well, and there are few leaves, it is time to pot the seedlings. It is ideal for repotting them into healthy soil so that they can blossom well. 

If you are germinating more than one seed in a jar and they all sprout, you’ll need to use separate jars for all of them to avoid crowding. Too many seeds in one jar of the tray can cause less airflow, and all of them may end up getting mold. 

I hope this information will help you prevent white mold on avocado seeds and roots. With the right amount of water, air, temperature, and soil, your seedlings will thrive into healthy plants.