G
Guest
Leaf Spot Fungus (LSF) aka Rust Spot .
Heads up UK ic'ers ...............................
This recent post by Oldtimer1 explains far better than i could .
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http://www.uk420.com/boards/index.php?s=&showtopic=105471&view=findpost&p=1099665
A few points that I think members should be aware of,
1. we have just had the wettest summer in the uk in over 150 years of records, the amount of fungus spores in the air are at levels never known before, in general horticulture and gardening circles plants are suffering with fungal problems across the board that never normally happen.
2. In the last 4 or 5 years there has been a steady rise in the reports of fungal infections in cannabis grow rooms and an ever widening number of types of fungal infections. One of the problems with this is that a grow room is ideal for the multiplication of fungi it only takes a few days for an infected plant to produce spores. In nature infected plants only produce spores in season, plants only get infected during a period where plants have leaves and the temperatures and humidity are right for spores to germinate. To combat this and carry on from year to year the fungi produce billions of spores so some survive the long cold and wet.
In a grow room every day 365 days of the year 24 hrs a day is ideal for the fungus to multiply, once a plant has started to produce spores the room will have millions and very soon billions of spores on every surface distributed by circulation fans, not only that but the air extraction will be ejecting a constant stream into the atmosphere.
There are two or three rather virulent fungi types that once in a grow room seem to be resistant to eradication, even after shutting down and using the likes of sulphur candles, bleaches, room clean and the like the rooms are still are not sterile and the minute clean plants are put back into the room, the infection cycle starts over again. With some fungi types even spraying the plants with protective fungi like Trichoderma’s to colonise them before introduction only slows infection down.
3. At this moment in time the best bet is to inoculate plants and mothers foliage with predatory fungi, it will give protection against all pathogenic fungi except the most virulent types, you should also be clear that once a plant has been infected and the hypha are growing inside the plant predatory fungi can not help. Some of the Mycorrhizal fungi such as those found in root grow will give some protection inside the plant. Again its the same thing plants need inoculating before pathogenic fungi strike.
Once a plant is infected the only way I know of at this time is to treat the plant with a systemic fungicide, this is a broad spectrum chemical that works through the entire plant sap stream and will kill all fungi both friend and foe. There are only two systemic fungicides registered for amateur gardening use in the uk at this time Myclobutanil and Penconazole. Final point I don’t know if any of the leaf fungal types that attack cannabis at this time are becoming resistant to either Penconazole or Myclobutanil.
It should be clear in members minds that pathogenic fungi rapidly gain resistance to fungicides. So these chemicals should not be used as a routine spray but only to treat an existing infection. If infections are treated at the earliest stage, usually the fungus is easily eradicated. If an infection is left to establish eradication becomes very hard to deal with.
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another quote by ot1 from a different thread
http://www.uk420.com/boards/index.php?s=&showtopic=105974&view=findpost&p=1098394
Its early stage leaf spot fungus.
Systhane is your best bet, it is a systemic fungicide, its much cheaper long term to buy the concentrate, instead of RTU spray. So you know what you are looking for, click here! Any good local garden should stock it. You need a proper pump up pressure sprayer to apply it. Treat all the plants not just the ones affected. Do not use during in the last 4 weeks of flowering.
edited to add. I just looked at your profile, its obvious you are growing organically. Sorry there is no organic control thats is effective at this time, once flowering copper is out as its very toxic both smoked ot eaten.
In future spray the plants with trichoderma before they can get infected, this is a good biological control that should protect against fungal infection, also treat you mothers if you have any...
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Thanks again to OT1 for sharing his knowledge .
these pix are from my own garden .....................
early stages......(PTK leaf)
Spreading .........(StrawDeez leaf)
advanced stage Leaf Spot Fungus............(various strains infected)
Petrol with bad LSF
i v seen posts where growers think it s a nutrient defiency or pest problem their plants are suffering from , when it s obviously LSF .
hopefully this thread might help those growers to establish exactly what they are dealing with and treat their plants accordingly .
peace to all
Heads up UK ic'ers ...............................
This recent post by Oldtimer1 explains far better than i could .
--------------------------------------------------------------------------
http://www.uk420.com/boards/index.php?s=&showtopic=105471&view=findpost&p=1099665
A few points that I think members should be aware of,
1. we have just had the wettest summer in the uk in over 150 years of records, the amount of fungus spores in the air are at levels never known before, in general horticulture and gardening circles plants are suffering with fungal problems across the board that never normally happen.
2. In the last 4 or 5 years there has been a steady rise in the reports of fungal infections in cannabis grow rooms and an ever widening number of types of fungal infections. One of the problems with this is that a grow room is ideal for the multiplication of fungi it only takes a few days for an infected plant to produce spores. In nature infected plants only produce spores in season, plants only get infected during a period where plants have leaves and the temperatures and humidity are right for spores to germinate. To combat this and carry on from year to year the fungi produce billions of spores so some survive the long cold and wet.
In a grow room every day 365 days of the year 24 hrs a day is ideal for the fungus to multiply, once a plant has started to produce spores the room will have millions and very soon billions of spores on every surface distributed by circulation fans, not only that but the air extraction will be ejecting a constant stream into the atmosphere.
There are two or three rather virulent fungi types that once in a grow room seem to be resistant to eradication, even after shutting down and using the likes of sulphur candles, bleaches, room clean and the like the rooms are still are not sterile and the minute clean plants are put back into the room, the infection cycle starts over again. With some fungi types even spraying the plants with protective fungi like Trichoderma’s to colonise them before introduction only slows infection down.
3. At this moment in time the best bet is to inoculate plants and mothers foliage with predatory fungi, it will give protection against all pathogenic fungi except the most virulent types, you should also be clear that once a plant has been infected and the hypha are growing inside the plant predatory fungi can not help. Some of the Mycorrhizal fungi such as those found in root grow will give some protection inside the plant. Again its the same thing plants need inoculating before pathogenic fungi strike.
Once a plant is infected the only way I know of at this time is to treat the plant with a systemic fungicide, this is a broad spectrum chemical that works through the entire plant sap stream and will kill all fungi both friend and foe. There are only two systemic fungicides registered for amateur gardening use in the uk at this time Myclobutanil and Penconazole. Final point I don’t know if any of the leaf fungal types that attack cannabis at this time are becoming resistant to either Penconazole or Myclobutanil.
It should be clear in members minds that pathogenic fungi rapidly gain resistance to fungicides. So these chemicals should not be used as a routine spray but only to treat an existing infection. If infections are treated at the earliest stage, usually the fungus is easily eradicated. If an infection is left to establish eradication becomes very hard to deal with.
--------------------
another quote by ot1 from a different thread
http://www.uk420.com/boards/index.php?s=&showtopic=105974&view=findpost&p=1098394
Its early stage leaf spot fungus.
Systhane is your best bet, it is a systemic fungicide, its much cheaper long term to buy the concentrate, instead of RTU spray. So you know what you are looking for, click here! Any good local garden should stock it. You need a proper pump up pressure sprayer to apply it. Treat all the plants not just the ones affected. Do not use during in the last 4 weeks of flowering.
edited to add. I just looked at your profile, its obvious you are growing organically. Sorry there is no organic control thats is effective at this time, once flowering copper is out as its very toxic both smoked ot eaten.
In future spray the plants with trichoderma before they can get infected, this is a good biological control that should protect against fungal infection, also treat you mothers if you have any...
--------------------------------------------------------------------------
Thanks again to OT1 for sharing his knowledge .
these pix are from my own garden .....................
early stages......(PTK leaf)
![](https://www.icmag.com/gallery/data/500/26202leaf_spot5.jpg)
![](https://www.icmag.com/gallery/data/500/26202leaf_spot4.jpg)
Spreading .........(StrawDeez leaf)
![](https://www.icmag.com/gallery/data/500/26202lsf_on_leaf_2.jpg)
![](https://www.icmag.com/gallery/data/500/26202lsf_on_leaf_.jpg)
advanced stage Leaf Spot Fungus............(various strains infected)
![](https://www.icmag.com/gallery/data/500/26202lsf_on_leaf_6.jpg)
![](https://www.icmag.com/gallery/data/500/26202lsf_on_leaf_5.jpg)
![](https://www.icmag.com/gallery/data/500/26202lsf_on_leaf_4.jpg)
![](https://www.icmag.com/gallery/data/500/26202lsf_on_leaf_3.jpg)
Petrol with bad LSF
![](https://www.icmag.com/gallery/data/500/26202petrol_lsf2.jpg)
![](https://www.icmag.com/gallery/data/500/26202petrol_lsf1.jpg)
i v seen posts where growers think it s a nutrient defiency or pest problem their plants are suffering from , when it s obviously LSF .
hopefully this thread might help those growers to establish exactly what they are dealing with and treat their plants accordingly .
peace to all
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