Powdery Mildew - early stage

[Jookie]

Hello!

I noticed white spots on one of the plants and immediately thought of Powdery Mildew. But can anyone confirm?

I've decreased the humidity to around 50-55% and sprayed a 1/2 milk solution on the targeted area (Later found out the milk solution should only be around 1/10. But will keep spraying for 10 days with a more diluted solution). Royal Gorilla is ~16 days old, while Shogun is ~19 days old. First hydro grow and Gorilla will be transplanted to HPA; while Shogun will be transplanted to DWC.

 

[Creeperpark]

High humidity and low airflow are the primary causes of white mold. Planting your weed where it cannot get proper air circulation, or overwatering your garden or potting media can create prime conditions for white mold to grow. At this point, I wouldn't spray anything on the leaves if it were me. Anytime there's an attack of any kind it's because something is out of place in the environment. Bugs, fungus, mold, humidity are all visual indications something in the growing environment is a miss. Before the white mold, there must be conditions conducive for mold. That's where one needs to spend effort.

 

[Jookie]

High humidity and low airflow are the primary causes of white mold. Planting your weed where it cannot get proper air circulation, or overwatering your garden or potting media can create prime conditions for white mold to grow. At this point, I wouldn't spray anything on the leaves if it were me. Anytime there's an attack of any kind it's because something is out of place in the environment. Bugs, fungus, mold, humidity are all visual indications something in the growing environment is a miss. Before the white mold, there must be conditions conducive for mold. That's where one needs to spend effort.

I fixed the humidity and there's a big fan blowing directly at both plants. But there may be too low passive intake of fresh air, since I have kept the exhaust at a minimum to prevent quick drops in humidity. Could that be the issue?

And thanks for the informative answer

 

[Creeperpark]

I keep my air gently moving around the plants so the leaves will dry and become tough and reflect mold spores. If the growing environment and leaves are "saturated with moisture" leaf tissue becomes very tender and soft, and that makes for an ideal spot for mold. The hypha is the building block of a fungus and is only interested in soft tender tissue that's easy to attach to. I run my sprouts and seedling in a dry environment for that very reason. Photo. humidity at 35%, temp 73 will keep the leaf tissue dry and resist mold.

 

[Jookie]

I keep my air gently moving around the plants so the leaves will dry and become tough and reflect mold spores. If the growing environment and leaves are "saturated with moisture" leaf tissue becomes very tender and soft, and that makes for an ideal spot for mold. The hypha is the building block of a fungus and is only interested in soft tender tissue that's easy to attach to. I run my sprouts and seedling in a dry environment for that very reason. Photo. humidity at 35%, temp 73 will keep the leaf tissue dry and resist mold.

Makes sense. When I researched about the best environment for the different phases; most suggested the 50-70% in the vegetative stage (dropping 5% pr. week). So that's just what I followed. While the RH should be between 40% to a max of 55% to prevent mold forming in the buds.

So you're suggesting to drop the relative humidity down to 35% - 40%? The current temperature is 73 fahrenheit / 23 celsius. Would also be a lot easier controlling the humidity around that level.

 

[44:86N]

Kind of early in the game for PM to develop. If it is PM, give your grow space a good scrub down, sterilize your hydro medium if you're reusing.

Watch the developing leaves. They look good.

Maybe get some Reliant Fungicide. I just used that on another type of plant, and it did knock down the fruiting body.

Good advise to follow on everything else.

 

[Creeperpark]

Its important to remember you have to sprout the seed and grow in low humidity. You can't drop your RH from 70% to 30% because the sprouts may be already dialed into high humidity. I'm just sharing something very important that I've learned and the way I grow seeds into big plants. I forgot to add something that helps me with my seedlings. I hang a string close to the plants and can watch air movement. If air moves fast or slow I can see it with my eye.

 

[Jookie]

Kind of early in the game for PM to develop. If it is PM, give your grow space a good scrub down, sterilize your hydro medium if you're reusing.

Watch the developing leaves. They look good.

Maybe get some Reliant Fungicide. I just used that on another type of plant, and it did knock down the fruiting body.

Good advise to follow on everything else.

Brand new Growdan Rockwool. The humidity have been out of control - I was stupid enough to program an RPi to automatically start an electric kettle to increase the humidity earlier, when it detected humidity below 50%. So when I woke up the humidity was over 100% because of false readings I just toke everything out of the room. Scrubbed everything in ethanol. Transplanted the two plants to their respective place and connected everything again.

Its important to remember you have to sprout the seed and grow in low humidity. You can't drop your RH from 70% to 30% because the sprouts may be already dialed into high humidity. I'm just sharing something very important that I've learned and the way I grow seeds into big plants. I forgot to add something that helps me with my seedlings. I hang a string close to the plants and can watch air movement. If air moves fast or slow I can see it with my eye.

Well, then we fucked up severely. Will adjust the humidity to 50% today, then slowly decrease it to 40% over the next week. Otherwise lesson learned to the next grow. Now when the humidity is lowered, more fresh air in the room from ventilation and a subtle wind from the fan. Could the fungus die out naturally without the use of a fungicide or milky-milky spray?

And thanks to both of you. It helps with the sudden minor panic attack from seeing these sweet two girls in pain.

 

[troutman]

50% will make for very slow growth.

I recommend you keep humidity at around 60% and you should be all good.

https://energyhandyman.com/knowledge...dity-monitors/

 

[RockinRobot]

Humidity is most important during LIGHTS OFF. Mold and Mildew like cool, dark and damp. I keep Rh up during days but I run a dehumidifier at night to keep Rh below 50% especially during flower. Never had an issue with mold or mildew doing it this way.

 

[ClearBarbedFunk]

Pm won’t survive above 24c, crank up your heat and kill it

 

[Jookie]

Humidity is most important during LIGHTS OFF. Mold and Mildew like cool, dark and damp. I keep Rh up during days but I run a dehumidifier at night to keep Rh below 50% especially during flower. Never had an issue with mold or mildew doing it this way.

Will focus on the temperature and RH from @troutman image. If I don't do anything for the humidity, then it will stabilize at around ~33% - 36%. That should be perfect for night time then? Then we will increase the humidity in the daytime up to 65%. Is all of this correct?

Will keep spraying the parasitic mold with some glorified raw milk. It seems to work already.

 

[FletchF.Fletch]

Hard to tell if it's actually Powdery Mildew. It's very early for it to develop. Are or were there other plants that had PM in that same space or nearby?

What EC are you currently running? Are they hand watered?

 

[Jookie]

Hard to tell if it's actually Powdery Mildew. It's very early for it to develop. Are or were there other plants that had PM in that same space or nearby?

What EC are you currently running? Are they hand watered?

None of the other plants have shown any symptoms. Yes, I have watered them by hand - but everything has been sterilized repeatly. All the tools, my hands, etc. The EC is ~1.6 with a pH of 5.8
I transplanted the Royal Gorilla (no symptoms) to the 6" netpot and my brother transplanted the infected Shogun. This was two days ago - could it be my brothers limited hygiene?

 

[FletchF.Fletch]

To me, it looks like the very beginning of nutrient burn at the tips. This should correct in short order as the Plants take hold and get going, but you may want to drop the EC a bit as they settle in. Perhaps a bit of nutrient solution splashed on the leaves, leaving a mineral deposit as it dried.

If it does turn out to be Powdery Mildew, SaferGro Mildew Cure will get it gone.

Part of me wants to say it's all because of the hygiene lacking brother.

 

[HempKat]

I'm inclined to agree with FletchF.Fletch I've seen powdery mildew up close and nothing I saw in any of your pics looked like powdery mildew to me. It looked more like some sort of nutrient issue starting to show but it was too faint for me to say for sure what nutrient issue it might be. It's been my experience that most pest and mold problems are the result of poor air flow and by that I mean the exchange of fresh air for stale air more then the movement created by a fan in the grow space. A lot of growers are reluctant to get the air exchange where it needs to be for the size of the grow space especially if the grow space is on the large size. The reason being that the fans rated for the right amount of CFM's (cubic feet of air per minute) tend to be expensive and pricey. So there is a tendency to favor stealthiness and cost at the expense of a proper rate of air exchange which can also lead to temperature and humidity issues. Another common mistake is people either forget to or improperly factor in the resistive impact on air flow things like carbon scrubbers and sound muffling devices and have on the exchange rate. If it does turn out to be powdery mildew you might want to check the air exchange rate of your space although humidity being allowed to rise above 100% for a period of time could definitely lead to mold issues.

 

[Creeperpark]

I run mine in the 30s % RH during seed sprout to seedling and then into veg. There will be days when it rises about 30% but for the most part, I keep it where you see it. I grow plants fast and without mold or any other environmental diseases.

The damping-off disease is a plant disease occurring in excessively damp conditions, in particular, the collapse and death of young seedlings as a result of a fungal infection. I see mold attacks a lot on ICMag and the main reason is because of excess moisture in the air and in the substrate.

 

[dimodz]

UV light & Ozon genrator can be helping

 

[Jookie]

To me, it looks like the very beginning of nutrient burn at the tips. This should correct in short order as the Plants take hold and get going, but you may want to drop the EC a bit as they settle in. Perhaps a bit of nutrient solution splashed on the leaves, leaving a mineral deposit as it dried.

If it does turn out to be Powdery Mildew, SaferGro Mildew Cure will get it gone.

Part of me wants to say it's all because of the hygiene lacking brother.

I gave them less than recommended by the nutritional recommendations, but god damn, this is a learning process Will dilute it to around EC ~1.2, then slightly increase it as the plant increase in size.

Will any form for Mildew Cure work or does it have to be specific to Cannabis strains or families? It is not legal in my country yet and most what I find in the stores for Cannabis are organic variants with oil, bee substance, cinnamon, etc.

We've ordered a humidifier with good reviews and an sensor for automatic managing to fix the humidity problem. Will set it to 60% at day and lower it to 50% - 55% at night - whatever seems most manageable.

 

[Jookie]

I'm inclined to agree with FletchF.Fletch I've seen powdery mildew up close and nothing I saw in any of your pics looked like powdery mildew to me. It looked more like some sort of nutrient issue starting to show but it was too faint for me to say for sure what nutrient issue it might be. It's been my experience that most pest and mold problems are the result of poor air flow and by that I mean the exchange of fresh air for stale air more then the movement created by a fan in the grow space. A lot of growers are reluctant to get the air exchange where it needs to be for the size of the grow space especially if the grow space is on the large size. The reason being that the fans rated for the right amount of CFM's (cubic feet of air per minute) tend to be expensive and pricey. So there is a tendency to favor stealthiness and cost at the expense of a proper rate of air exchange which can also lead to temperature and humidity issues. Another common mistake is people either forget to or improperly factor in the resistive impact on air flow things like carbon scrubbers and sound muffling devices and have on the exchange rate. If it does turn out to be powdery mildew you might want to check the air exchange rate of your space although humidity being allowed to rise above 100% for a period of time could definitely lead to mold issues.

I've tried to take some better images. Royal Gorilla doesn't seem to face any nutritrional issues, but here's the updated images of both. Bad ventilation seems probable - we don't have an intake vent (It is ordered) and because of the manual adjustment of humidity, we haven't increased the exhaust vent, since it drops the humidity too quick. So hopefully the added intake vent with a automatic humidifer will allows us for more venting and better control.

I run mine in the 30s % RH during seed sprout to seedling and then into veg. There will be days when it rises about 30% but for the most part, I keep it where you see it. I grow plants fast and without mold or any other environmental diseases.

The damping-off disease is a plant disease occurring in excessively damp conditions, in particular, the collapse and death of young seedlings as a result of a fungal infection. I see mold attacks a lot on ICMag and the main reason is because of excess moisture in the air and in the substrate.

So Cannabis can thrive even in low humidity areas? Is it specific strains? But your plants are looking very healthy and beautiful