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Fusarium On Marijuana Plants

Fusarium On Marijuana Plants

Fusarium is a type of soil-dwelling fungus that has the potential to absolutely devastate your marijuana plants’ root systems. It can have different effects on different strains of marijuana.

In some strains, it causes Fusarium wilt, and in others it causes Fusarium root rot. The only plants that are really not at risk for getting hit with Fusarium are those grown in hydroponic growing systems. Soil is necessary for Fusarium to occur. It happens most often in warm, tropical areas of the world.

Besides plants that are consumed by people (any edible or inhalable crops), fusarium actually does not cause harm to most plants. It is, therefore, a specific threat to marijuana plants – and therefore marijuana growers.

 Signs of fusarium

Signs of fusarium on weed

The tricky fact about Fusarium is that it can sit in the soil for years, completely dormant. During this time, it will basically be impossible to notice its presence. Fusarium spreads through water movement, as well as through touching gardening tools or farm equipment. As soon as they come in contact with a viable host plant (i.e. your precious marijuana plants), they jump into action and come alive.

You will first begin to notice Fusarium when you see little dark spots on your plant’s lower leaves. The affected leaves will quickly become yellowish brown, and then the tips will start turning upward, and wilting will start its deadly course.

Leaves will wilt but they won’t fall off, and the stems on your plant will droop significantly. This process is what we call “Fusarium wilt.” It shows that Fusarium has set into motion its deadly plan for your plant.

Download my free marijuana grow guide at this link for more growing tips

As for Fusarium root rot, you might not notice its effects right away. The roots will become red-colored, which of course you won’t notice until that red color travels up through the stem. The stem will swell and then break open, which can lead to an onslaught of diseases and pests that will cause further harm to your plant. The plant will then wilt and collapse, and the Fusarium will go further and further up its stalk.

Fusarium clogs up the xylem vessels of your plant, which means that water and nutrients will not be able to travel through and reach the other parts of the plants. This is why the root rot has such a devastating effect on your entire marijuana plant.

Not sure if your marijuana plants suffer from a Fusarium infection? Check the article Marijuana diseases for a list with pictures of all possible marijuana diseases

How to get rid of fusarium

Get rid of fusarium on cannabis

As soon as you notice the problem with your plants, you need to remove the affected parts right away. Do not let the plant matter remain there and decompose, especially since it’s sitting in the soil. If it remains, it will only ensure that any future plants growing there will be devastated as well.

If you’re growing your marijuana plants outdoors, they are at risk for having a Fusarium attack. This means you should go into the growing season with a plan in case the worst should indeed happen. Indeed, when your plants have all been infected with Fusarium, your crop is lost.

You can relocate to a new outdoor growing location, move your operation to an indoor grow room, utilize containers for growing instead, or give up altogether. You simply can’t fight an attack of Fusarium. Your plants are lost, as are any seeds that may have already been produced – seeds help spread the attack, so they won’t be useful anyway. Throw everything away.

Download my free marijuana grow guide at this link for more growing tips

Crop rotation is a good rule of thumb, even if your marijuana garden doesn’t experience a Fusarium fungus attack. Continuously growing marijuana in one location will cause the soil to “get used” to the marijuana plants, making it a good place for problems to arise.

There are some ways you can prevent it from happening to your plants in the first place, however. Whenever you use any kind of tool, always sterilize it thoroughly after use. You should always use compost for your soil (compost that has been aged properly) to introduce beneficial bacteria that will help fight off any bad fungi.

If you are living in a location that naturally has clay soil, your risk of getting Fusarium is already lower. Since clay has a higher pH level, it naturally suppresses fungus. Loamy soils can often be useful as well since they might be housing microbes that keep Fusarium under control – this happens most of all when marijuana and other healthy plants are growing together in the same area.

Marijuana plant symptoms

Leaf Symptoms:
– Small brown spots on lower leaves
– Yellow-brown colored lower leaves
– Leaf is curling upwards
– Wilting leaves

Plant Symptoms:
– Wilting
– Red stem
– Swelling stem
– Breaking open of stem
– Red-colored roots

Fusarium is actually being used to kill off marijuana plants by the US government in the “War on Drugs” campaign, which gives you an idea as to how powerful this fungus really is. It is both devastating and selective, making it the perfect weapon to kill off your marijuana plants. Good luck!

Remember that plants with strong genetics have less change of getting sick and are less vulnerable for pests and diseases. So make sure to buy cannabis seeds from a trusted seed bank.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible


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Comment Section

13 thoughts on “Fusarium On Marijuana Plants

By Robert j on 22 November 2012

great reading, I justy dealt with this issues over the last 3 months. Licked my ass. I lost 3 plants and saved 7 by using thyme oil and actinovate. Good luck to ya

By Danielle on 28 September 2016

How did you use the thyme oil?

By WeeW on 20 February 2013

Has cure for fusarium or you need cut all the plants?

By Basil on 20 February 2013

You can use a fungicide for prevention but when your plants are infected it’s very hard to cure

By Robert J on 5 March 2013

I just read a few articles and learned that papaya extract of lactic acid has amazing results. Also read that wearing flip flops in the garden (which feels natural) is about the worst thing you can do. Toenail fungus is the best carrier known to scientists for being the guilty party in the reciepe for disaster.

1- Dont over water
2- add lots of pear-lite to your soil and other peat mosses and fluffy things to ensure prompt drainage and drying.
3- if you begin to see gnats and little flies coming out of your soil get the actinovate out.

By Jo on 23 September 2016

I have it on the trunk of some of my smaller, but best looking budding plants. Wondering if it’s safe to smoke?

By Diane Wilks on 13 August 2017

Help! My outdoor starting to flower plants leaf edges are curling and all new growth and flowers are brown. I can’t figure out what is wrong. Can anyone help?

By Bert on 11 February 2018

If you have fungus or mildew problems. Use 15 ml of 35% hydrogen peroxide in 1 litre distilled water spray all plants, mildew disappeares. Any fungus’s can be killed buy applying 30ml of 35% hydrogen peroxide in 1 litre distilled water and flood soil. It will also remove any insect and any eggs from the soil. You will need to add enzymes to replace the good bacteria killed in the application. The added oxygen increases fertilizer uptake.

By Grower on 27 February 2018

Any instances of fusarium in hydroponic production? Drip or DWC? This article claims no fusarium outside soil-based cultivation, however I have first hand experience with plant pathology tests proving otherwise.

By latewood_ILGM on 28 February 2018


Fungus can spread and I am not surprised by your claim. I believe Hydroponic was overlooked due to small % of plants affected. Wouldn’t you agree. This article is more about recognizing fusarium wilt, and not necessarily where else it may spread aside from soil.

Thanks. Happy growing.

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