What Causes Bud Rot and Prevention

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Bud Rot Causes and 7 Tips of Prevention

Bud Rot (Botrytis Cinerea) is the most common cannabis disease. It is more harmful than the powdery mildew we talked about earlier.

While this disease can attack every part of your plant, and rot your buds from the inside out. It is most commonly found on the buds and colas, which are the most useful and precious part of your harvest.

Finding bud rot in your plants before harvesting can be devastating. So much time, money, and labor you've spent to grow healthy crops. It is a well-known fact that almost every grower faces bud rot at least once in their career.

But that shouldn't stop you from seeing your cannabis business success!

By understanding the bud rot, you can set up effective protection to prevent their entry.  So let's read this article about its topic and how to prevent it.

What is Bud Rot

Bud rot or gray mold is a botanical fungal disease. It comes from a fungus known as Botrytis Cinerea, a necrotrophic fungus affecting many plant species.

Someone called bud rot “Big Bud Disease” or “The Curse of the Successful Grower”.

When the environment conditions becomes conducive, the mold rapidly rots the buds, leaves, and stems. Soon enough, it will proliferate from inside and spread out to the rest, ruining the buds and damaging your entire yield. 

That's why we suggest bud rot prevention is much more important than treatment.

what is bud rot 01

In spite of being an admirably resilient plant, cannabis is still just that - a plant. Like all plants, cannabis can be affected by many diseases and harms, including viruses, fungi, bacteria, insects, and even some animals. 

Bud Rot is just one of the most common cannabis diseases.

First of all, let us know how to indentify bud rot.

Bud rot - canna just a plant

Bud Rot Causes

Now that we understand the essential cause of bud rot is the Botrytis Cinerea, let's consider all the reasons why your plants could be suffering from it.

First off, we need to understand what conditions the fungus or mold likes. It means if we know the conditions that allow bud rot to thrive, thus we can know the causes of bud rot, and how we could take the measure and prevent it effectively.

Below, we have summarized the conditions that could be promoting bud rot in your cannabis plants, including:-

  1. 1
    Poor Air Ventilation
  2. 2
    High Relative Humidity Level
  3. 3
    Stagnant Air Temperature
  4. 4
    Dense and Fat Buds
  5. 5
    Extreamly Dense Foliage
  6. 6
    Weak Immunity in the Harvest
  7. 7
    Plant Genetics
  8. 8
    Insect Wounds
  9. 9
    Wet and Rainy Conditions
  10. 10
    Inadequate HVAC for grow rooms
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What causes 02 | What causes bud rot | Altaqua Grow Room Hvac

Identifying Bud Rot

Bud rot isn't specific to any geographic locations. Moreover, it can attack plants at any stage of life, most commonly found on the dense and fat buds before harvesting. It will develop and take on different appearances depending on what stage it is in.

What does Bud Rot Look Like

Bud rot may also look white and fluffy on the outside, which is the actual spores of the fungus.

Cannabis bud rot first appears as a white, wispy sheen over your buds. When left to grow and produce spores, it turns gray and then black (sometimes it is dark purple) while turning your once dense and supple buds into a mushy and slimy mess.

Look at the bud rot images.

bud_rot_ what does it look like 01

What deos bud rot look like 

cannabis

-bud rot-

When you notice your plant looks sick or shriveling. But you are not positive what the culprit is. "There must be something wrong" - it is your instincts. Since you found the leaves, stems, and pistils are pretty different from the plants in other areas, just like patches all over the plant. 

The bud rot botrytis can attack every part of your plant, most commonly found on the buds. But the affected parts are usually noticeble and catch your attention easily. 

Bud Rot Signs

What did bud rot do with your plants, and what are early signs of bud rot?

Bud rot can attack every part of the plant, and it goes through several stages before it matures and spreads. It is challenging to detect in its early stages since it rots your buds from the inside out. 

But with the following list of bud rot signs, identifying but rot become easy.

Bud Rot Sign 1 - Stem

As it starts to occur and spread, the botrytis bud rot will attack your plant's stem, making it first turn white and wispy, and then become a pale grey color and turn into slimy mass. The stems start losing their rigidness and can no longer stand straight. 

Bud Rot Sign 2 - Leaves

The infection will keep progressing, and you will notice your plants lose their color and start looking wilted and yellow with burnt leaves. This is because the fungus is smothering your plant and inhibiting chlorophyll production.

Bud Rot Sign 3 - Buds

Once it's done with the stems, botrytis bud rot will make its way to the female plant's moist buds. The leaves will wither into a brown shade, and the pistils will soon follow. Eventually, the buds will be covered entirely in the gray mycelium, turning them into a gray-brown slime. Occurring in the late stages of flowering, bud rot is easily visible to the naked eye and should prompt immediate action from you, as it spreads quickly and can even reach out to other plants in your facility.

Bud Rot Sign 4 - Colas

It might just attack the biggest and fattest buds first, or it could form mold spots all over your marijuana plant. Additionally, you might be able to observe the cola turning into a darker color and getting dried out.

Look for the following bud rot pictures  (symptoms)

Bud Rot Symptoms

How can Bud Rot Spread 

For bud rot to occur, mold needs to make contact with your plants first. It may seem like an unlikely occurrence, but the dusty spores of the mold are quite easily transported, reaching your plants through air, water, and other pollinators, like contamination by farm tools.

Once the spores get to your yield, they form a wound or tear in the external tissue and enter the buds. The Botrytis Cinerea then continues to break down the surrounding bud and spread out to other areas of the plant.


How Long does Bud Rot take to Spread

Bud rot spreads quickly and dangerously

The white, wispy sheen (mold) may be seen only for a day or two before it becomes dark brown or gray. It is difficult to spot when starting, since you’ll probably never notice this sign before it changes.

Then you see the colas (leaves around, buds and pistils) become dark, dried up, dying.

In less than a week, the bud rot can spread the whole grow room if the conditions becomes conducive, such as high humidity level, poor air ventilation, and stagnant air flow etc.

Can We 

Stop Bud Rot?

It is a common tactic to spray fungicides at the flowering stage of your plant. Growers are also known to use Neem Oil or sulfur on affected buds. But the fact is, these practices do more damage than good.


Fungicides or oils have zero effect on bud rot. All they do is make your yield look, smell and taste horrible. Every grower needs to know that fungicides can only be used as preventative measures before the buds have formed.

Remember, if the infection has become widespread, you must cut down the whole plant in order to protect the rest of your plants. Don't risk your entire harvest in hopes of saving a single infected plant.


So, with bud rot, early detection and prevention is crutial. You should check your plants every day and perform a thorough assessment. 

How to Treat Bud Rot if it was Infected?

If the core is displaying the signs we mentioned above

  • Isolate it by cutting it out and quarantine that area of your grow room. Sample and investigate all other plants nearby to determine if the botrytis cinerea has had time to spread out.
  • Changing your clothes and wearing protective gear when moving from one grow room to the next.
  • Cut down the infected part using trimmers and store it in a sealed container to prevent any accidental spreading.
  • Dispose of this container and sanitize all gardening equipment used as well as your clothes.
  • Before concluding your bud rot removal, do conduct a thorough assessment of the whole plant to ensure all the affected areas are removed quickly.

During harversting,

  • Make sure to leave space between hanging branches as your buds dry out or create an optimal environment for the drying process.
  • You can even try out various speed-drying techniques to limit the time that your buds spend in conditions that could promote Botrytis cinerea.

7 Tips to Prevent Bud Rot

How to Control Bud Rot

Inspect and Assess Plants Daily

With bud rot, early detection can make all the difference for your cannabis plants. You should inspect your plants daily and perform a thorough assessment. Look between all the cracks and any crevices of suspect buds to find out if it have bud mold.

Isolating Infected Areas

If the core is displaying the signs we mentioned above, isolate it by cutting it out and quarantine that area of your grow room. Sample and investigate all other plants nearby to determine if the Botrytis cinerea has had time to spread out.

Wearing Protective Gear

Sometimes, a plant mold on bud will have grey-colored webbing or white, dusty spores. These spores can spread and travel to infect the rest of your plants too. Try to be vigilant when handling plants with bud rot by changing your clothes and wearing protective gear when moving from one grow room to the next.

Sanitize All Gardening Equipment

If your plants are already victim to bud rot, it is best to cut your losses and take down that part of the plant. Hopefully, you should be able to salvage the rest of your crop. Cut down the infected part using trimmers and store it in a sealed container to prevent any spores from accidentally spreading.

Dispose of this container and sanitize all gardening equipment used as well as your clothes. Before concluding your bud rot removal, do conduct a thorough assessment of the whole plant to ensure all the affected areas are removed quickly.

Moreover, it would help if you didn’t think your plants are safe from bud rot after harvesting your buds. They can still catch the spores and become moldy. 

Therefore, you need to be extra careful and ensure your buds don’t come in contact with the fungal spores.

Make sure to leave space between hanging branches as your buds dry out or create an optimal environment for the drying process. You can even try out various speed-drying techniques to limit the time that your buds spend in conditions that could promote Botrytis cinerea.

Prevent Bud Rot: Start with Humidity Control

We have gone over what is bud rot, factors that cause it, and prevention control. Now, we will discuss the best ways to stop bud rot from damaging your crops in the first place.

Inspect the Humidity Levels for Your Grow Room

The most important thing you need to do is carefully monitor the humidity levels in your grow room. Humidity should always be kept at a relative humidity (RH) of 40% to 50% to prevent bud rot.


Since Botrytis rarely exists in dry conditions, you should invest in an effective grow room hvac or dehumidifier to keep your crops healthy.

Let Your Air Circulate

Adequate air circulation will ensure your plants get cool, fresh air to breathe. It also reduces the chances of fungal spores existing in the air and settling on your crop.


Creating good air circulation pathways in your grow room is a must-do for preventing bud rot.

Remember to Consider Different Strains

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Another critical component to consider is the strain of your plant. Some plants are more susceptible to developing bud rot than others.

Therefore, it is best to avoid planting those strains and instead opt for a mold-resistant cannabis plant. It will allow you to maximize profits from your yield and ensure a healthy harvest all year round.

We have compiled a list of various mold-resistant plants, categorized by indoor and outdoor strains, which you can look into for your subsequent yield.

Outdoor Strains

Holland’s Hope

Best to harvest in mid-September up to early October.

Jamaican Pearl

Should be harvested before its trichomes turn amber-colored.

Frisian Dew

Best in Northern climates that offer plenty of sunshine with cooler temperatures at night.

Indoor Strains

Sweet Tooth

The Hawaiian roots give it excellent mold-resistant properties.

Moby Dick

Easy to grow with a bountiful yield.

Important Note

Before picking out a strain to grow, be sure to consider all of its requirements. These will help you create the perfect environment for optimal growth and plays a vital role in preventing bud rot.

Determine the Dehumidification Size

Picking out the right dehumidifier will play an essential role in stopping bud rot. Your dehumidification size should be determined by how much moisture removal your grow room requires. Start by taking out an average reading of your humidity levels for a week, and then calculate how much moisture removal you need.

Your dehumidifier device capacity is usually measured in pints of moisture removal per 24-hours. Use this as a standard metric to pick out the right dehumidification size for your grow room.

 Want to get the "right dehumidificatication size"? 

At the End


Bud rot is often considered an inevitable phenomenon, a yield loss that every weed grower has to face. But, you can stop your plants from suffering the same fate. By growing the right strains of cannabis in the right environment, maintaining the relative humidity, ensuring sufficient airflow, and investing in a dehumidifier, you will be successful in preventing bud rot.

For further assistance on maintaining the correct humidity levels for your crop growth, reach out to our dehumidification system experts today.


Tags

botrytis cannabis treatment, bud rot


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