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Purple Power

Pest: Root Rot

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Pest: Root Rot





( Multiple species  )




Special Species Notes


Root rot can attack plants that are growing in any system, including hydroponic, container, coco, and soil-based growing systems. It can happen indoors or outdoors although root rot is more common indoors due to poor drainage, and/or overwatering. The excess water makes it very difficult for the roots to get the air that they need, causing them to decay. Make sure from the get-go you are keeping the soil well-drained and the temperatures low enough. Since this infection is usually a result of watering your plants too much or too often, this should be considered for both indoor and outdoor grown cannabis plants. Pay special attention to how much your plants are absorbing, and make changes accordingly.


In hydro if the water is not properly aerated, root rot can occur. This is usually accomplished by use of an air pump, air stones, air diffusers and by adjustments of the frequency and length of watering cycles where applicable.


Although once the fungus has invaded it will be all over your garden, it is surprisingly choosy when it decides which specific plants to attack.


Root rot mostly affects hydroponic systems, but can also result from over watering your plants in soil or other medium. Basically anytime the roots are sitting in wet conditions for too long, they are at risk of developing root rot.

  • Plants may appear over watered or droopy, sometimes plants wilt overnight
  • Brown, slimy or smelly roots
  • Plant leaves often start turning yellow or white
  • Leaves may start dying and falling off rapidly
  • Oftentimes you'll see what appears to be a random mix of nutrient deficiencies on the leaves - this is due to the fact that the plant can't absorb nutrients properly at the roots even if they're there
  • Plants drink much less water than usual





Common Species:


Root rot can be caused by several different organisms including types of bacteria, fungi and parasitic oomycotes. Although the symptoms are similar between different types, they don't always look exactly the same. However, growers generally refer to all types of unhealthy root browning as just "root rot."


Many cases of root rot are caused by members of the water mold genus Phytophthora; perhaps the most aggressive is P. cinnamoni. Spores from root rot causing agents do contaminate other plants, but the rot cannot take hold unless there is adequate moisture. Spores are not only airborne, but are also carried by insects in the soil.


Fusarium solani, Fusarium oxysporum, Macrophomina phaseolina, Rhizoctonia solani, Sclerotium rolfsii, Verticillium species





Root rot is a condition found in both indoor and outdoor plants, although more common in indoor plants with poor drainage. As the name states, the roots of the plant rot. Slimy brown roots are caused by pathogens.


Usually, this is a result of overwatering. The excess water makes it very difficult for the roots to get the air that they need, causing them to decay/rot.


The problem with this infection is that, since it travels underground and starts at your plant’s root system before hitting the rest of the plant, it is extremely difficult to detect until it’s too late. You will probably start paying attention when your plant’s leaves start wilting and turning yellow with brown edges. If you examine the roots, you will be able to notice the Pythium. Otherwise, however, the symptoms will just be like any other fungal damage.







First signs:




Healthy roots are always white or cream-colored, but Pythium-affected roots are brownish and might emit a mildew or rotting smell. Keep in mind, Nutrient-stained roots are not slimy or smelly and all the roots are evenly dyed the same color. You'll be able to see each individual "strand" on healthy cannabis roots. You also won't see leaf symptoms or wilting on the plant itself.


The first sign of root rot (besides brown roots) is usually the leaves start getting sick, wilting or drooping. Plants affected by root rot may spontaneously start getting sick, with leaves becoming yellow or bronze. The cannabis plant itself starts drooping, wilting, or otherwise looking like it's dying.


Root rot often strikes immediately after a reservoir change, especially for young plants. If this happens to you it's recommended to only top off your reservoir for the first several weeks, and wait to do the first full reservoir change until after the roots are well established. This allows young roots time to build up a biofilm that protects them against root rot during reservoir changes.


After the wilting, other leaf-specific signs will probably follow, including burning, brown spots, yellow or white coloring, dying and dropping off of leaves, and strange signs of nutrient deficiencies in the leaves. The final symptom comes from the fact that, since it’s the roots where the problem arises, they are unable to function properly, including improper absorption of nutrients. This is shown by the plant as nutrient deficiencies, but when you check the water everything nutrition wise is there. If you haven't looked at the roots, please do now. Your plants are now screaming there's a major problem.


You may also noticed that your plant(s) has been taking in less water than usual. If this is the case alongside the above signs, you should jump into action mode to rid your plant of the Pythium. 


Plant symptoms


Weak Stems; Slow Growth; the entire plant Wilting or Drooping.





Leaf symptoms




leaf symptoms that can look like almost anything: cannabis leaves get burnt edges or tips or die; yellow / bronze / brown or dark spots or stripes; Pale Color Leaves; Yellow Leaves - New Growth; Yellow Leaves - Lower older leaves;  old leaves drop off: slow or abnormal growth; the leaves have curled edges; upward or downward; wilting/drooping; nutrient deficiencies; and other unusual leaf symptoms.


The wilting is often soon be followed by other symptoms to the leaves, especially burning, brown spots, nutrient deficiencies, spotting, and other unusual leaf symptoms.




Root symptoms


Brown, slow growth, smelly, mushy, slimy. Can appear to have snot on the roots. You will also notice that affected plants will start drinking less water.  As the root become more infected and die, they can't absorb the water and nutrients the plant needs to live.




You should check the roots for these signs as soon as your plant starts showing signs of wilting. You always need to check the roots to be sure one way or the other.


You won’t need to try so hard to see these symptoms if your plants are growing in a hydroponic system, of course, but there are ways to check within a soil setup as well. Simply dig down through the soil and look at the roots to see if they are damaged. Be careful when digging to not damage them.


If you do examine the roots, you will find them to be off color, soft,  watery, and smell fowl. These are the signature symptoms of a Pythium infection. Cannabis roots with root rot often look slimy (though not always), in fact sometimes it almost looks like they have snot on them.


Some types of root rot affect the roots below the surface of the water, and sometimes it's only the roots above the surface of the water that turn brown, while the roots in the water stay white.

After a while, the most external layer will fall off the roots, making the stringy inside visible.




Life cycle


Healthy roots are white to cream-colored while roots affected by root rot are brownish, often slimy and may smell like mildew or rotting.


Roots need water, but if they are get water without enough oxygen they are much more susceptible to root rot. This is often caused by too-hot conditions, overwatering, and/or not enough bubbles dissolving oxygen into a DWC water reservoir. Root rot is caused by many different types of organisms, and even if you create a great environment it can strike if you don't take precautions.


Your cannabis plant starts drooping, leaves start getting sick, and roots are brown, smelly and/or slimy. These are all symptoms of cannabis root rot. Sometimes the plant will not wilt, or will recover from wilting while still showing other signs of root rot. This is your plant powering through, though you still want to take care of the problem before it gets worse. Although wilting is common, you cannot be sure your plant doesn't have root rot just because it's not wilting. It's much more important to look at the roots in order to accurately diagnose root rot. The wilting is often soon be followed by other symptoms to the leaves, especially burning, brown spots, nutrient deficiencies, spotting, and other unusual leaf symptoms. You will also notice that affected plants will start drinking less water.



How it spreads


Root rot multiplies extremely quickly and spreads through giving off tiny spores that cannot be seen by the naked eye. These spores are the real threat, as they will take your cannabis garden from just one plant being affected to having your entire crop infected with root rot.


When it does spread, it does so underground, following a water trail between root systems. It germinates while traveling through this path so it is ready to spread once it reaches the roots of its new host. It then disperses itself through the plant’s tissue and creates resting spores that will soon germinate. This is how the fungus is allowed to continuously damage your whole garden, plant by plant.


What to do for preventative use


It's important to note that damage from root rot is permanent to both the roots and the leaves. Old brown roots will never turn white again. Brown leaves will never turn green again. You need to instead be looking at new growth for signs of root rot recovery. You want to keep your eyes peeled for new white roots emerging from the old brown sick roots. The same goes for the affected leaves – they will eventually die, but if your plant is recovering then, new leaves will look healthy and green. You'll know that recovery is happening when new white roots start growing.


Preventative measures with hydroponic growing systems will vary slightly from measures for a typical soil setup. The number one thing you need to worry about in a hydroponic growing system is cleanliness. Keep the environment and every piece of equipment used in the setup clean at all times.


The main thing you should do (or maybe should have done) is prevent Pythium from happening in the first place. You first and foremost need to keep your growing site clean, healthy and well-maintained, which will generally help lower the chances of the parasite invading your garden in the first place.  Soil should be consistently well-drained and rich in nutrients – this will ensure that the Pythium cannot live happily in the soil, therefore discouraging it from invading at all.


It can be tough to get rid of root rot and many growers prefer not to deal with it or feel it's easier to just scrap the entire plant and/or garden and start over once they identify the fungus as the problem. However, if you're growing in the same spot, using the same equipment, and method you're likely to get it again, and there are some techniques that can cure your plant of root rot problems.


Because cannabis root rot can be caused by different pathogens, a solution that solves the symptoms for one grower may not necessarily work for another. That being said, there are ways to fight against root rot no matter what kind you have. If you would like to save your infected plant, however, there are certain steps you can take. In order to get rid of root rot successfully, you need to take a two pronged approach. You will need to treat the plant's root directly since they are the source of the problems. And you will also need change the plant's environment so that root rot no longer has a good place to grow, have the opportunity to spread and thrive. If you can’t complete the environmental changes, there is no point in trying – the root rot would simply return again and again, no matter what. Your plant can completely recover from root rot as long as you catch the problem early enough, so it's important to stay vigilant of root rot during your first couple of grows, especially when growing cannabis with hydroponics.


Remember that plants with strong genetics have less change of getting sick and are less vulnerable for pests and diseases.


Keep Everything Clean


You want to keep your grow area as clean as possible at all times to stop bacteria before it starts. Before you begin your grow, it's a great idea to clean all grow-related items to kill any bacteria or fungus..... don't forget the floors, walls, doors, and ceiling; Bleach and rubbing alcohol. change air filters, etc. Every time, I use my scissors or feed my plants, I clean everything that was used including the area where it done.




In a hydroponic system, you need to be sure to consistently and frequently change the reservoir water. A minimum of every two weeks is a good rule of thumb, although many growers recommend even more frequent changes. It should be checked daily. Changing the water will allow your plants to have more nutrient access and will also avoid nutrient toxicities and deficiencies. Also clean out any dead matter (dead roots, leaves, etc.) or other types of plant debris that get into the reservoir right away and keep it out of your reservoir. because they will provide a breeding ground for bad bacteria as they start rotting – so don’t give them the chance to grow. If you do notice organic matter in the reservoir, fish it out as soon as possible.


You also need to keep light away from your reservoir water and roots – it will heat it up too much, and that in combination with the extra light provides a great place for bad bacteria to grow. You can also prevent bad bacteria from getting into your system by cleaning all the equipment before you start growing. This will kill bacteria before it ever has the chance to infect your plants.


For soil to avoid root rot, it is best to only water plants when the soil becomes dry, and to put the plant in a well-drained soil. Pest control is also a helpful way to prevent Pythium invasions. Some pests (i.e. the fungus gnat) carry fungus with them, so by keeping them away you will also keep your plants safe from contact with fungi. Make sure you don’t water your plants too much or too often. Make sure you let the top layer of your soil (about an inch deep) dry completely after each watering. This should keep the fungus gnats away.


Like most fungi, Pythium thrives in moist soil with warm temperatures (70 degrees Fahrenheit or higher) and high humidity. Be sure not to over-fertilize your plants. Instead, include a compost for your plant’s growing foundation – just make sure the compost has been aged correctly. A soil mixed with this type of compost is also more likely to keep pests and other diseases away because of all the good bacteria and nutrients.


Top off reservoir for first few weeks, without doing a full reservoir change until after roots are well established.


When it comes to nutrients and plant growth in a hydroponic setup, it's important to change your reservoir water regularly. This is especially important in the flowering stage when the plant is very sensitive to nutrients and pH. Regularly changing your water every 7-10 days will help your plants get better access to nutrients, and help prevent deficiencies and toxicities.


However, when your young seedling or clone is first getting established in your hydroponic system, it doesn't have an established a colony of good bacteria around the roots, and has not yet grown a biofilm that protects the roots against pathogens. During this initial period, a full reservoir change can throw everything off balance, and your roots have to sort of "start over" from the beginning. 

That's why it's recommended for the first 3-4 weeks of your cannabis plant's life to only top off the reservoir with additional nutrient water, and hold off on a full reservoir change until your plants have grown lots of roots with a healthy layer of biofilm over all the roots and sides/bottoms of the tank.


Lots of bubbles


Root rot can occur in hydropinic applications, if the water is not properly aerated. This is usually accomplished by use of an air pump, air stones, air diffusers and by adjustment of the frequency and length of watering cycles where applicable. Hydroponic air pumps function in much the same way as aquarium pumps, which are used for the same purpose.


A way of increasing your plants’ oxygen intake in a hydroponic system, you could purchase a large air pump and air stones. More bubbles and surface movement, in general, is useful in increasing the oxygen content of the water. It is incredibly beneficial to try to get as much oxygen as possible dissolved in your water. Oxygen helps your plants grow, plus Pythium does not like water that has lots of oxygen, making this a twofold way of keeping your plants healthy. Therefore it's a good idea to buy a BIG air pump and big air stones for your hydroponic system. The more bubbles and surface agitation, the better, as this dissolves more oxygen into the water. As long as the roots are not being very disturbed, you can't really go wrong with adding more oxygen.


An example is one EcoPlus 2 Air Pump w/2 Outlets for each 10 gallon container (which each hold 6 gallons of water), 2 large air stones per air pump (since this one 2 outlets - this helps make sure there's plenty of oxygen in the water healthy roots and faster growth).


Keep grow room cool


Lower the temperature of the grow space under 80°F, and even better under 75°F.  This also lowers the temperature of the water in your reservoir. Water can't hold much dissolved oxygen at higher temperatures and your plants need oxygen to "breathe." In an ideal world, the maximum recommended temperature for the water in your reservoir is around 72°F (22°C) and some growers will go to great lengths to keep their reservoirs very cool.


Getting more oxygen to the roots not only helps fight root rot, it makes your plants grow much faster. If it's too hot in the grow space, you're much more likely to run into root rot as well as overall droopiness.


Another option is to specifically add good bacteria to the water in a hydroponic system, which will help with any root-based diseases or conditions, as well as making nutrients more available for absorption by the plant. When using a supplement like Hydroguard that fights root pathogens directly, you can usually keep the temperature quite a few degrees higher without a problem.  The "secret sauce" in Hydroguard is a specific type of bacteria called Bacillus amyloliquefaciens. It survives in hydroponic reservoirs better than other types of Bacillus bacteria and fights many root ailments including different types of fungi, bacteria and water molds. It not only gets rid of and prevents root rot, but there's some evidence Bacillus a. may actually help lower salt concentration in the plant tissue itself. Botanicare's Hydroguard is the newer, improved version of Botanicare's popular "Aquashield" root supplement.


To treat root rot and ensure it never returns to your hydroponic marijuana setup, you will first need to change the temperature of the growing space. This will also lower the water temperature in your reservoir, which is perfect. By lowering the temperature, you are allowing more oxygen to be held in the water, which your plants need to properly combat this parasite. Pythium comes when the water temperature is too high (usually above 72 degrees F ). If the temperature is kept 72 degrees or lower, you will greatly reduce the chances of root rot occurring. If you have a good supplement, however, higher temperatures will likely be okay.


No light to the roots or the reservoir


Don't let any light get to your roots or reservoir water, as it provides heat and light which will promote the growth of algae and bacteria (and not the good kind).


Hydrogen Peroxide (H2O2) Is Only a Temporary Solution


While some growers recommend treating cannabis root rot with H2O2, it’s better to not use hydrogen peroxide (H2O2) to treat Pythium. All H2O2 does is cause bubbling near the dead brown roots (or any organic matter), which is why people believe it's helping. While adding hydrogen peroxide to your water will kill most bacteria and pathogens, including the ones that cause root rot, it is only effective in your system has only a temporary effectiveness for a day since the H2O2 is quickly converted to oxygen and water, meaning it would require daily treatments. All the H2O2 will be completely gone from the water within 24 hours. For this reason, it might not work at all, and it will kill all the beneficial bacteria in the process. It is not recommended that you use hydrogen peroxide to deal with Pythium.


Therefore, if you use hydrogen peroxide as a treatment for root rot, you will need to treat your water daily to prevent re-occurrences until you actually fix the problem that is causing your root rot in the first place. Some people have tried used commercial grade H2O2 before, and were never able to use it to get rid of root rot, so this is NOT RECOMMENDED as any type of long term cure.

H2O2 kills most of the bacteria in the reservoir, including any good bacteria you've added, and does nothing to address the underlying problem. You can't sterilize away root rot. Although H2O2 does kill bad organisms, it leaves enough of it there to repopulate your reservoir. As common as the advice to use H2O2 for root rot is, there's never been a case by a real grower who was actually able to get rid of root rot with H2O2.


When cleaning the system, use beneficial bacteria that has been added to your normal nutrient solution – this will work better than peroxide for preventing Pythium outbreaks. Since Hydrogen peroxide (H2O2) kills the good bacteria as well as the bad, you will need some of that good bacteria for fighting off infection. Hydroponic systems are particularly at risk from this fungus, simply because an infection would spread rapidly and would be basically impossible for you to stop.


In addition to treating root rot, some people like to use Hydroguard or Aquashield as a preventative. It is surprisingly effective even in hot, unclean reservoirs.






You also will need to change the environment itself, so the Pythium no longer has the environment its needs to live. An example, if the grow room is over 80F, lower the temperature add an air conditioner or have the lights on at night. Remember hot air can hold more moisture vs cooler air. Adding frozen milk jugs to the reservoir.  If you can change the environment as well as treat the roots, you should be aware that the affected roots will never recover. Because of this fact, you need to look to the new growth to see how your plant is faring with the treatment.


You can also purchase root controls. If you do this, make sure the package specifies that it works for Pythium or root rot. And keep in mind that even some controls that claim to kill root rot will really take care of Pythium, so you really have to know what you’re buying. Other effective methods of control are copper treatments, oil sprays with clove, coriander oil, sesame oil, plus Trichoderma (a “good” fungus) and mold control.


You should notice the new white roots growing out of the old brown dead ones within just a day or two of receiving Aquashield in the reservoir. By this point, the plant has stopped showing any new symptoms and appears to be growing normally. When you can barely see any signs of the old brown, and all the new roots generally appear white and healthy. The plants on top are lush, healthy, and fast-growing. Some growers will remove the old burnt leaves since they'll never recovered as new healthy leaves come in.





The link below will take you to "An Intro to beneficial bugs and beneficial insect food" it has a list (been worked on) to pests and beneficial insects





Classy, sassy, and a bit of a smart assy

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