Root Rot 101

Root Rot is most common in growers using DWC (deep water culture). But growers using soil or coco can experience root issues as well. 

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Many growers will refer to any root issues as “root rot”.

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In reality, there are many different pathogens and organisms that can cause problems in your roots. However, as most of the symptoms appear the same, they are just grouped together as root rot.

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There are different bacteria, fungi, and algae that can cause root rot.

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Healthy cannabis roots in hydroponic setup grown with Future Harvest nutrients

⠀⠀⠀Healthy roots grown with Future Harvest nutrients

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What is Root Rot?

Root rot (sometimes referred to as Pythium) is a fungus that can take over the roots of your plants.  Root rot can take over very fast and can easily spread through microscopic spores. If one plant has root rot, chances are they all do.

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The roots are the most important part of your cannabis plant. You must keep them happy!

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Unhappy roots will result in almost immediate nutrient deficiencies, over or underwatering symptoms, and stunted growth. Roots provide your plant with oxygen, water, and nutrients, without healthy roots, your plant will die off. You have to be careful not to overwater and drown your roots, while also providing your plant with enough water in order for it to survive. Every plant is different and will require different amounts of water depending on your growing conditions. Factors that will affect how much you water include: humidity, temperature, growing conditions, size of pot, growing medium, etc. 

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Roots infected with Root Rot

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Prevention is more effective and easier than trying to fix an outbreak.

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How to prevent the threat of root rot:

  • Healthy soil
  • Beneficial bacteria / microbes
  • Don’t overwater (It’s always better to underwater than to overwater! Remember: you can always add more water, you can’t take water away)
  • Add perlite to your soil or coco to help drainage and oxygenation

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Click HERE to read our Tips for Better Root Health

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How to Identify Root Rot:

  • Brown, slimy roots (may be twisted together) 
  • Dropping, unhealthy leaves
  • Can resemble over or underwatering symptoms in soil plants 
  • Burnt edges or tips 
  • Yellow or brown spots or stripes 
  • Nutrient deficiencies 
  • Root Rot can cause changes to pH in your nutrient solution, which could translate into deficiencies

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    Healthy cannabis roots grown in hydroponics with nutrient staining grown with Future Harvest nutrients

    These roots are healthy, but have some brown staining from dark colored nutrients. 

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    How to Know if your Roots are just Stained from Nutrients?

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    Healthy roots will be white! But, some dark colored nutrients can stain roots a darker color. 

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    • Even brown color all over
    • Roots won’t be slimy or smelly
    • Roots won’t be twisted together 
    • Leaves of plant look healthy

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    Roots infected with Root Rot
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    Signs your roots are unhealthy:

    • They appear brown and slimy 
    • They are bunching and twisting together 
    • They have a bad smell

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    If your root zone is having an issue, it will show in your leaves. Leaves may appear to have tip burn, brown or yellow spots, curled or clawed edges, and more. Deficiencies may present themselves as the roots are no longer able to adequately take up nutrients, essentially starving your plant. 

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    Your plant may seem healthy other than the roots.

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    Oftentimes, growers think the roots aren’t an issue and will ignore them. If you leave root rot for too long, your plant will start suffering and it may be too late to save it. 

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    What causes Root Rot?

    • Light leaks
    • Heat
    • Lack of oxygen 

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    Soil and coco growers will run into the issue of stagnant water. This old water pools at the bottom of your pots and your roots sit in it. 

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    Transplanting too Early - your young plant needs time to grow strong roots before you move them. Transplanting can shock and stress your plant and roots, and introduce new pathogens. 

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    Underwatering or overwatering symptoms are oftentimes a sign you have a root issue. 

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    Root rot is most common in hydroponic systems! 

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    In a recirculating system, once one plant has had Root Rot, it is safe to assume it has spread everything. Sometimes discarding all your plants, grow media, and equipment, and starting fresh is the best course of action.  ⠀⠀⠀⠀⠀

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    How to Treat Root Rot:

    • Address any issues (light leaks, temperature changes, etc.) 
    • Change the plant’s environment 
    • Add beneficial bacteria 
    • Add oxygen (airstone, bubbler) 
    • Clean and sanitize growing equipment 
    • Introduce H₂O₂ to your nutrient solution 

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    Never use both H₂O₂ and beneficial bacteria together! The H₂O₂ will kill off all the healthy bacteria

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    Root rot is sometimes impossible to fix. Most growers are better off discarding their plants and starting again once root rot has taken hold. With that being said, many root conditions are often referred to as root rot, and some of them can be saved.

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    Preventing root rot is your first step to combating it!

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    How to combat root rot:

    • Introduce a beneficial bacteria product
    • Introduce oxygen
    • Ensure there are no light leaks. Not only do roots not like light, but most pathogens need a warm bright environment to survive. 
    • Ensure your temperatures are low 

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    Because hydrogen peroxide turns into water and oxygen, you will have to treat your growing medium with H₂O₂ daily. 

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    If you have root rot, we recommend performing a full system clean. This may consist of fully cleaning out your grow media and lines with bleach. Make sure you fully flush your system after bleaching to ensure you don’t harm your plant. Ideally, all your growing equipment would be thrown away and replaced once you have had Root Rot to prevent any further outbreaks. 

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    Infections can occur in future crops because of contaminated growing equipment!

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    ⠀⠀⠀⠀Roots infected with Root Rot

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    Prevent the threat of root rot:

  • Healthy soil
  • Beneficial bacteria / microbes
  • Don’t overwater (It’s always better to underwater than to overwater! Remember: you can always add more water, you can’t take water away)
  • Add perlite to your soil or coco to help drainage and oxygenation
  • Make sure your temperature and humidity is within range
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    Temperature and Humidity:

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    Temperature:

    • During the day (lights on) we recommend keeping your grow between 24-27°C (75-80°F)
    • At night (lights off) we recommend keeping your grow between 20-22°C (68-72°F)

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    Always closely monitor the temperature and humidity levels in your grow room to ensure your plant is growing in the optimal conditions.

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    When growing hydroponically, you’ll also want to monitor the temperature of your nutrient solution. (Keep it between 18 and 21°C / 64-70°F)

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    Benefits of a colder reservoir temperature:

    • Increased dissolved oxygen⁣⁣⁣⁣
    • Decreased chance of pathogens (root rot thrives in atmospheres above 22°C⁣⁣⁣⁣
    • Overall healthier plant ⁣⁣⁣⁣

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    A Hotter Reservoir Temperature Can Result In:

    • Pathogens such as root rot⁣⁣⁣⁣
    • Increased PPM as your plant absorbs more water but not nutrients (can result in nutrient burn or a lockout).⁣⁣⁣⁣

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    Effective Ways To Cool Your Reservoir:

    • Water chiller⁣⁣⁣⁣
    • Insulation⁣⁣⁣⁣
    • Increased reservoir size⁣⁣⁣⁣

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    Humidity:

    • For clones and seedlings keep humidity at 65%-80%⠀⠀⠀⠀⠀⠀⠀⠀
    • During vegetation, keep the humidity between 55-70%⠀⠀⠀⠀⠀⠀
    • During early flowering, humidity should be between 40-55%⠀⠀⠀⠀⠀⠀
    • Plants in late flowering are most comfortable with a lower humidity. Keep it between 30-40% 

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    Other factors that can cause root issues:

    • Rootbound
    • Too big of a container
    • Too small of a container
    • Too hot or too cold 
    • Your soil is too thick

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    Healthy Roots grown with Future Harvest nutrients
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    Any questions? Email us at marketing@futureharvest.com or send us a message on Instagram @futureharvestdevelopment and we will help you as best we can!

      Published by Future Harvest

      Bio:
      Future Harvest | Grow Better |

      E-Mail: marketing@futureharvest.com

    • Apr 09, 2021
    • Category: Articles
    • Comments: 0
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