Is it possible to eradicate leaf spot fungus?


If not please tell me because I can’t keep chasing this, it’s just not worth it.

I have no problem pulling down everything and using the hospital type fungicides to kill everything but my concern is, as I do have a background as an amateur Mycologist (rip P.F.) I know spores are very difficult to control.

I can kill everything in the grow room but I’m sure that they’ve been tracked through my whole house and I will never get them all out, so after treating how do I stop it from reinfecting?
-Thank you


This is exactly what a sulfur burner was designed for to treat fungus in green house they are cheap to run and can be set on timer to run during lights out but fungus does need moisture and proper conditions to thrive so you can prevent it coming back. sterilize space then paint or poly before adding plants improve airflow add a filter to your intake as well as exhaust wear clean clothes and foot wear everytime
I actually have shoes just for my grow room. Do away with any old soil sterilize all gear pots lights ballasts fans
Airflow is biggest thing keeping clean fresh air moving keep space clean no dead plant matter poly is excellent for this you can seal and cover walls floors and cieling in a non organic easily cleaned poly and keep it clean. I want an airlock in my next grow a place to put on cover alls and shoes before entering. anything can be managed with prevention


Yellow leaf spot, also known as leaf septoria, are caused by Septoria cannabis and S. neocannabina. These are fungal pathogens aimed specifically at marijuana plants.

It is brought about by warm weather and rain and effect marijuana grown outdoors. It may also show up in nitrogen- deficient plants. Read this article and learn how to identify and treat yellow leaf spot.

Signs of leaf septoria
Signs of leaf septoria weed

Yellow leaf spot initially shows up on the lower leaves of your plant. These spots may vary in shade from white to a grayish brown to yellow, initially displaying little circular lesions. Once it starts to grow it starts looking like a bump and its size continues to increase.

Yellow leaf spot will harm the leaves and often times the stems of the plant, although it won’t cause the crop to die off. If for any reason this is not properly cared for it will lessen the marijuana plants yield. The affected leaves will become dry where the spot is and overtime break and produce a hole at the point where the spot started off.

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

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How to avoid and cure leaf septoria
Cure yellow leaf spot cannabis

The most affected leaves will become totally yellow, dry out and fall off. You will want to get rid of the leaves that fell off or else you will end up with a landing turf for spores to overwinter. Basically, they will hide out until the weather warms up and then that’s when they will wreak havoc. Yellow leaf spot spores do their dirty work through traveling by water, wind and clinging on to things that pass by.

You can avoid the damage yellow leaf spot causes your plants through crop rotation. Basically, after every harvest you will pick a new location to plant. If you are not able to do this, then after harvest, completely get rid of all leftovers from the last vegetation and till the soil really good to make sure all remains are gone.

Written from ours truly Robert Bergman,
Happy growing hope this helps


@Majiktoker This is the same thing Will posted in another thread and it’s not really much help for an indoor grow but thank you anyway for putting it up.

@Donaldj I don’t know what a sulfur burner is ? …I’ll try to Google or ask about it next time I’m at my hydro store, thanks

What I think I’m getting is it can only be controlled, is that correct ?

Anyone else with any input on this?


lol it can be killed and prevented but is always present a healthy plant is far more tolerant and resistant to molds and infections and much like you or I we come into contact with germs spores and viruses all the time which don’t effect us. All I am trying to say is yes you can get things back to sterile and clean but that doesn’t mean prevention isn’t a must


…watching the video it says I can’t use it past week 2 in flower and it’s just not going to work for me ( plus he says it’s toxic ? )

I’m going to put everything in flower tomorrow. I’m going to use the gas when everything is done and start again

I’ll probably use neem oil and sodium bicarb on a regular rotation when I start again this fall

  • thanks again Donald


Water and hydrogen peroxide work too
I use it to kill most problems on my fruit trees
both molds and fungi even black spot on my roses.
I would use food grate if these are buds around.


@Iva What ratio would you mix it at?


depends on how strong a plant for fruit tree
i use 1-2 table spoon per liter for a spray as a middle point
5 for roses

this is for the 3%


Sulfur burns are bad for LEDs


Try brewing a strong tea with lemongrass and spraying on daily for three days. Complete saturation of plant and top of soil.


The mold protector will help.

Hope these help,