Those little dark flies will multiply. They lay there eggs in the soil. To keep them aways use diatomacous earth. It's natural, covered the dirt and they won't land to lay there eggs. It will form a crust, but you can disturb it when you water. I don't think it's nitrogen either. Good luck.
Help!!! Rust-brown spots, some yellowing
- Thread starter feelingreen
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feelingreen
Active Member
is there anything i should avoid, considering my girls are already in the flowering stage and such? i already have some neem oil on hand (also have some garden safe insecticide with pyrethrin, but the 3 in 1 is recommended for gnats, doesn't sound quite as effective as a pyrethrin bomb) , so that would be convenient, but in researching around i've heard mixed reviews, and i'm not sure exactly what would be the best way to apply it. how big would the larvae be to the naked eye? would they be pretty easy to see?
the damage has pretty much halted, but it still seems like they're stressed
the damage has pretty much halted, but it still seems like they're stressed
feelingreen
Active Member
I think that my girls are going to be OK. 
As long as that peat moss doesn't go haywire again, blah.
Some singed leaves on the main cola and taller side branches from growing too tall for my case and into the lights.
As long as that peat moss doesn't go haywire again, blah.
Some singed leaves on the main cola and taller side branches from growing too tall for my case and into the lights.
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dreadful1
Active Member
This is exactly the same problem I am having!!I assumed it was a ph problem as well or a fungus of some kind because my air flow is not exactly perfect.I just noticed these spots last night and it's spreading quickly.I have nine W Widow and they all have spots as of this morning.Growing with MG soil,18-10-10 and I noticed a couple little black flies or gnats as well(eerily similar scenario)have yet to resolve it.Was it the peat moss acidity,or did the h202 help?what made it stop for you!!!!????
feelingreen
Active Member
The spots were most likely from a calcium deficiency, stemming from the peat moss acidity, yes. I have yet to amend my soil as much as I should, probably, but all I did was flush w/ pH'd water+H202, 2tsp. per liter recommended. H202 is acidic, though, so make sure to pH. Have you checked your pH? After that, the rapid spread stopped, but the few leaves already affected with the most spots didn't recover, so I snipped them.
The next day was another flush with H202 solution, then a day to let the soil dry out (I only flushed the day after because although the damage had stopped, still wasn't looking the best), the next day I supplemented for the deficiencies my plants had, since I would have flushed away a fair amount of nutes. When I fed them, I added the cal to the water and watered almost like a flushing again, just with less than I would have normally, especially since the plants were still recovering.
I would check for fungus gnats, as well. If you disturb your plant, look for them to come out of the top of the soil - that's where they like to hang out. For the larvae, put pieces of potato on the top of your soil, they're attracted to it and should come munching on it eventually, then dispose of them - this isn't a solid method for getting rid of them, just confirming that you indeed have an infestation.
There are a bunch of remedies for gnats - neem oil+soap+water, gnatrol, pyrethrin-containing products, etc., putting a layer of sand over the soil, etc.
If it's spreading that rapidly, though, it's probably not the gnats that are the immediate issue. Do you have any pics? What's your soil composition? Nutes? How far along are you in the grow? It might be worth your while to transplant with some better soil, as MG seems to be screwing around these days, and amend with dolomite lime during the transplant, or do so now. You'd get better/more responses with a new thread, but I'm still curious.
Peace
The next day was another flush with H202 solution, then a day to let the soil dry out (I only flushed the day after because although the damage had stopped, still wasn't looking the best), the next day I supplemented for the deficiencies my plants had, since I would have flushed away a fair amount of nutes. When I fed them, I added the cal to the water and watered almost like a flushing again, just with less than I would have normally, especially since the plants were still recovering.
I would check for fungus gnats, as well. If you disturb your plant, look for them to come out of the top of the soil - that's where they like to hang out. For the larvae, put pieces of potato on the top of your soil, they're attracted to it and should come munching on it eventually, then dispose of them - this isn't a solid method for getting rid of them, just confirming that you indeed have an infestation.
There are a bunch of remedies for gnats - neem oil+soap+water, gnatrol, pyrethrin-containing products, etc., putting a layer of sand over the soil, etc.
If it's spreading that rapidly, though, it's probably not the gnats that are the immediate issue. Do you have any pics? What's your soil composition? Nutes? How far along are you in the grow? It might be worth your while to transplant with some better soil, as MG seems to be screwing around these days, and amend with dolomite lime during the transplant, or do so now. You'd get better/more responses with a new thread, but I'm still curious.
Peace
feelingreen
Active Member
Also, where is it affecting the plant? New growth, old? Where on the plant?
Edit: Personally, upon thinking about it, I'd go ahead now and add 1/2-1" sand to the top of your soil, if that's what you're using, if you feel there's a fairly high probability you have fungus gnats, as it'll f*** up their growth cycle - they look just like fruit flies/little black flies, and like I said, are often hanging out around the soil... since as larvae they enjoy munching on your plants' roots, and as someone said, this can produce "phantom cal-mag" symptoms.
That's because the little devils are sucking the energy right out of your plant and harming the root system, potentially causing permanent damage - root damage doesn't heal, so wherever they munch, from then on down it's gone. That's why it's also useful to add H202, because it helps clear out any dead/decaying root matter and is just generally a good, cleansing water addition for potted plants.
Just in case, I'd certainly look into those maybe-kinda-sorta gnats.
I'm sandless, but I had neem on hand, so I looked around and found this useful thread for that:
https://www.rollitup.org/general-marijuana-growing/8962-how-use-neem-oil-without.html
Some discussions around here I found about fungus gnats in general:
https://www.rollitup.org/marijuana-plant-problems/418340-fuck-fruit-flies.html
https://www.rollitup.org/bugs/433563-have-fungas-gnats-tried-glue.html
Edit: Personally, upon thinking about it, I'd go ahead now and add 1/2-1" sand to the top of your soil, if that's what you're using, if you feel there's a fairly high probability you have fungus gnats, as it'll f*** up their growth cycle - they look just like fruit flies/little black flies, and like I said, are often hanging out around the soil... since as larvae they enjoy munching on your plants' roots, and as someone said, this can produce "phantom cal-mag" symptoms.
That's because the little devils are sucking the energy right out of your plant and harming the root system, potentially causing permanent damage - root damage doesn't heal, so wherever they munch, from then on down it's gone. That's why it's also useful to add H202, because it helps clear out any dead/decaying root matter and is just generally a good, cleansing water addition for potted plants.
Just in case, I'd certainly look into those maybe-kinda-sorta gnats.
I'm sandless, but I had neem on hand, so I looked around and found this useful thread for that:
https://www.rollitup.org/general-marijuana-growing/8962-how-use-neem-oil-without.html
Some discussions around here I found about fungus gnats in general:
https://www.rollitup.org/marijuana-plant-problems/418340-fuck-fruit-flies.html
https://www.rollitup.org/bugs/433563-have-fungas-gnats-tried-glue.html
dreadful1
Active Member
Wow...that's the best response I've had yet..haha.I think the gnats may have moved on,not sure but I have only ever seen 4-5 of them and it has been a while now.few days anyway.I ended up giving them more fertilizer which I know is a bad idea but after researching it seemed I was having deficiencies of all sorts.I drilled more and larger holes in my pots because it seemed they were not getting enough air and drainage.After the feeding I left town for a night,came back and they perked back up quite a bit,it seems the spotting has stopped and they resumed growing...seems better now.I actually got these plants from a friend who decided it was to much work and I have no idea how long he had them going for but they were 3-4 inches when I took over.I have had them for almost 5 weeks now and the tallest plant is around 15 inches,the shortest is around 8.I was caught quite unprepared so have been cramming,trying to get the knowledge and equipment as they grow.Hence the PH problem....I live in small town Canada and would you believe,no litmus paper,no ph monitors of ANY kind!!I have placed some paper on order though.should be here soon!!To compensate I have been using fresh river water straight out of the mountains as I was told it was ideal.(could be wrong).A large part of the confusion for me was that the MG ingredients only stated N-P-K levels(18-10-10)and nothing about your micros..copper, manganese ,calcium etc.I was unsure if the soil contained proper amounts..and still am actually..which is why I added the other fert.It had the micros stated.Also if I flush to much to soon won't I over water?I do want to get the nutes out of the soil thoroughly before I flower because of the high Nitrogen.And could these gnats be there in full force ravaging my plants and I wouldn't see them???(potato trick I guess)once I get my litmus,I may try the h2o2 if they are still acting up.Thanx again and I will keep you posted if you like,I'm sure could use some advice on a few other things haha....peace!!
feelingreen
Active Member
On second thought, if you don't have to (sounds like they're doing A-OK now), skip the H202, really only for emergencies - it can affect the positive bio life in your soil.
Yes, they certainly could be there and you wouldn't know, but in a week or two they would pupate and pop out of the soil - sometimes I've even seen them come out of the drainage holes, since they're always hanging out around the roots. It's OK if you just flush them every now and then while the soil's still wet from a previous watering, I'd say. Overwatering more so occurs from continuously keeping up with such a practice.
You do still want some nitrogen, by the end of their life cycle they'll have used all the nitro from the soil and will start taking it from the fan leaves (natural process). Given that, you don't want there to be too little around maturity, and trust me, your plants won't have trouble consuming what's already there. A bit of a flush is reasonable, just not too much, I guess I'm trying to say. Sounds like you're taking good care of them, it's critical to watch those micronutrients (some even consider cal a macronutrient along with NPK). Just about all of them, if neglected, can lead to symptoms as harmful as NPK deficiencies. Hope your test strips get there soon, and that they serve you well!
Happy growing.
Yes, they certainly could be there and you wouldn't know, but in a week or two they would pupate and pop out of the soil - sometimes I've even seen them come out of the drainage holes, since they're always hanging out around the roots. It's OK if you just flush them every now and then while the soil's still wet from a previous watering, I'd say. Overwatering more so occurs from continuously keeping up with such a practice.
You do still want some nitrogen, by the end of their life cycle they'll have used all the nitro from the soil and will start taking it from the fan leaves (natural process). Given that, you don't want there to be too little around maturity, and trust me, your plants won't have trouble consuming what's already there. A bit of a flush is reasonable, just not too much, I guess I'm trying to say. Sounds like you're taking good care of them, it's critical to watch those micronutrients (some even consider cal a macronutrient along with NPK). Just about all of them, if neglected, can lead to symptoms as harmful as NPK deficiencies. Hope your test strips get there soon, and that they serve you well!
Happy growing.