UK growers beware Leaf Spot Fungus aka Rust Spot

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

Shit, i have a very bad case of that fungus going on. What the hell can I do about it? The plants are a week from harvest, are they safe to smoke?

Cheese ravaged with this bloody fungus:

Those pics are 10 days ago, it's got progressively worse since, eating away the upper fan leaves. The plant is at 57 days now and onyl a few days left before harvest. Strangely the OG Kush next to the Cheese has no trace of the fungus, seems resistant.

thanks for adding your pics BH . also noticed some strains are more resistant than others . well fed plants seem to fight it off better . when nutrients are low at the end of flower it really seems to take a hold .

Yes, it does seem to affect some plants worse than others, that Cheese is the worst affected, whereas the OG Kush next to her is fine:









This Purple Afghan was affected, but the buds are fine and I don't think the fungus has reduced the plant's performance at all:









So I'm not sure what to make of this fungus, it makes the topmost fan leaves brown and die, but the plants seem to carry on regardless, my RH currently is 45%, maybe I can get rid of it with a bleach or peroxide cleaning.

systhane or dipthane

systhane or dipthane

i been using sythane by baynard for pm and its got that sorted,systhane is systemic and used to cure current diseases and fungi ,

as a preventive measure i then switched to dipthane also by baynard which stops infection from inside ,,stopped me getting pm and also i have no lsf so i'd say it works

Hiya Hazy

I haven't treated the OG for PM, just been keeping an eye on it and not a spot of PM, I am a jammy git it seems.

I might have to treat my next batch of plants when I put them into flower tho to avoif LSF, although LSF doesn't seem to be a serious problem, my plants are doing fins, just have a few brown dried fan leaves.

Got links to those products hazy?

nice pics BH . the og looks very frosty . also looks well fed which definately helps them fight the infection. most of the hybrids i v grown haven t shown much resistance late in flower , with PTK showing no resistance from a young age .
Sour Mist were the only plants i v grown which weren t treated with fungicide to show hardly any effects right through to harvest . plants right next to them looked like the petrol i posted above .

thanks for the input Hazy , that s very handy to know . i ll try that to limit the chances of the fungi building resistance to the Sythane

helpppppppp wats this

helpppppppp wats this

hi lads could you tell me wat this is on my leaves im a novice at this but due to the bad summer weve had and now the cold is setting in my plants are turning purple on leaves.ive been growing outside in pots do you thin i should harvest now just that buds ar small cheers the british bull

here s the link to the Sythane product matey

http://www.bayergarden.co.uk/products/product.aspx?productid=30



and the dithane

http://www.bayergarden.co.uk/products/product.aspx?productid=2

Thanks for the links hib, much appreciated. The OG Kush has been getting the same nutes as the other plants - ec 1.8-1.9 ph 5.5-5.9, she is a heavy feeder and has not had a sign of overfert, whereas some slight clawing and the odd slightly burnt tip have been seen on the others.

Hiya Bullhead. Your plants look the picture of health to me, i think too much importance is often placed on plants being 100% perfect, of course, the healthier the better, but a little issue doesn't ruin a plant completely - my Purple Afghan is lovely despite the LSF. I'd let those plants go as logn as you can, keep an eye out for mould and try not to let them get too wet, if there is heavy rain, try and shelter them. If they do get really wet, bring em inside to dry out for a day. Mould is the big killer outdoors in the UK, I once had a Durban Skunk that was 6 foot tall and about 8 foot wide, a huge bush, she was fine and I went away for the weekend, came back after 4 days and she was riddled with mould, lost pretty much all of her, had to settle for making a load of Durban Skunk bubble hash from the moudly buds.

cheers matey as a novice see when is the latest you can harvest them,i let them out when sunny then bring them into the garrage on a night i diddnt no whether its getting to cold now.cheers

The cold won't kill them, as long as there is not a bad frost, you need to get a cheap 30x magnifier and check the trichomes, when they turn cloudy and a third have an amber tint, then you're looking at ripe marijuana.

Well, god damn,

A few harvest back I was having leaf deficiency symptoms in flower and just couldn't fix it no matter what I tried until now I still hadn't a clue.

But after seeing the OP's pics I think this is it.

Here are some pics of my plants, very similar to the OP's:

Does this look like LSF?

Doesn't look like lsf more looks like ca- or nute burn. Look in to threads in *****. Plant magic essence is right product im this case.