Powdery mildew, treatable?
- Thread starter Jorro
- Start date
Hobbes
Well-Known Member
Attempting to prove Spinosad can handle PM
So. At the end of the summer I had 3 og kush auto seeds left over. I decided to pop them and say fuck it as I have other plans come in March for outdoor grows. One of the plants this morning began to show some PM on the leaves. I have said to many before that spinosad can suppress the pm and...
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Rurumo
Well-Known Member
Are you in veg or flower? I'd spray them down with a potassium bicarbonate solution to start. In veg, a neem/silica spray works well too-silica works similarly to potassium bicarb, they both just raise the PH up past where the PM is willing to continue living. It's hard to eradicate though, so you'll need to continue regular spraying until buds start to form. In the future, check out the biofungicides for prevention-Southern Ag Biological Fungicide works great for so many things, Regalia is good but expensive, Serenade, and there are others that people like too, but I haven't tried personally like Actinovate. Once you've had it, you'll likely have it again so you will probably need weekly preventive sprays in rotation. Throw one of the biofungicides in rotation with neem/silica and potassium bicarb and you've got a decent little program. Also, be sure to clean up your grow space really well and wipe it down with h2o2 in between crops.
Jorro
Member
Unfortunately, wasn't able to snap pics due to the rush to take care of it before lights out. It is on very early veg, recently transplanted from solo cups.
I noticed these spots as I was doing my first topping and pruning out some of the dried/discolored lower leaves. I believe I have found the culprit, a faulty sensor on my humidifier allowing it to fire up when lights out and temp drops (hit 84% RH the night before).
Having not seen your response prior to my attempt to take action, I did wipe each location with wet paper towel, disposing of each towel after each wipe. I cut and carefully disposed of the leaves that had the most growth (none had more than a small spot maybe .5cm in diameter). Followed by a healthy spritzing of bee safe organic 3 in 1 spray.
Today, plants seem to have taken well to the topping and mildew treatment. No signs of stress, no apparent PM.
Any input on my approach would be appreciated. I now see it wasn't what is recommended by you experienced growers, but if I continue with the bee safe every week, should that keep it at bay? Thank you for all the help.
Wizzlebiz
Well-Known Member
Haha. I forgot to update that.
Hobbes
Well-Known Member
I've found that foliar sprays mostly just beat back the PM, then it comes back a week later. Where you're in veg you may be able to kill it with a thorough spray.
If it does come back in veg a good way to eliminate it is a Sulfer vaporizer, it'll coat the whole plant with a PH antagonist. You don't want to do it in flower.
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Nivola Sulphur Vaporizer (Sulphur Burner) 110V > Pest & Disease > Valley Indoor
The Nivola sulphur evaporator is a well designed evaporator which evaporates the right amount of sulphur safely and at the same time keeps energy consumption to a minimum. The chimney effect guarantees an optimum distribution of the sulphur in the greenhouse. The sulphur evaporator is suitable...
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Aheadatime
Well-Known Member
Pm is defeatable permanently. It can remain dormant in leaf tissue in some cases, but it only displays symptoms when certain conditions are met. Humid, dark, and cooler environments with little to no airflow. Some rare strains of PM like hot weather, most like cold. But they all prefer darkness, little airflow, and big swings in humidity/temp from day to night. If your temps and humidity are reasonable and stable, and you have great airflow, lots of light, and a clean under-canopy, it will not resurface, period. By clean under-canopy I mean occasionally defoliated plants, no large fan leaves resting upon other fan leaves, and no lower branches permanently getting no direct light.
You found the culprit with your nighttime humidity, so making sure that's fixed for good is the first step. I'd recommend doing a heavy defoliation, followed by either a sulfur spray or a sulfur burn. Sulfur burns work more effectively to treat the plants as well as the grow space, but release gases you don't want to inhale, so research how to properly do it if you choose that route, and please be safe. You don't want to be using sulfur in flower, but you can use it up to the second week if you must. I've heard it makes flowers taste and smell bad lol.
Regalia works to invoke a systemic acquired resistance (SAR) against PM from an early age, veg/clone stages/early flower stages. Oxiphos works similarly, but rather than invoking an SAR, it invokes an induced systemic response (ISR). This is just a quicker-acting version of an SAR with the benefits not lasting as long. They work well in tandem, and both work better as foliars but will work just fine in a reservoir too.
I haven't worked with the Bee Safe. It uses a 5% solution of sesame oil as it's mode of action. All I could find on sesame oil with a quick search was a study done comparing ammonium oleate, malic acid, potassium laurate and sesame oil. To quote;
"Sesame oil was the most successful of the compounds tested. Results were inconclusive in the preventative experiments. However, in the curative experiments, sesame oil was moderately-to-highly effective. Two weeks after application, plants applied with sesame oil had 62 percent less powdery mildew than plants in the control group. However, sesame oil was slightly toxic. The plants receiving a 5 percent sesame oil application lost 26 percent more leaves than plants in the control group. Sesame oil is not recommended for ornamental plants because it decreases the plants’ aesthetic qualities."
(http://www.diggermagazine.com/controlling-powdery-mildew/)
I'm not really into using oils to combat fungi and mildews, but I don't have alot of experience vs PM. Just had it once, and completely eradicated it by fixing nighttime humidity, burning sulfur 3 times 2 nights apart each, and tank mixing as advised. I do use Method1 PPS every few weeks in veg as a general preventative, which is an essential oil mix, so maybe that helps a bit. Sure smells good lol. Don't stress. Educate yourself and just kill the damn thing. Everything is beatable.
Jorro
Member
Thank you for your responses, and more importantly, your time. I have closely researched each product and method youve described and believe I will attack this from many fronts. Sulfur burn, as well as a biofugicide along with a potassium bicarbonate solution and neem/silica. Unless this combination would adjust the surface ph too much and cause damage?
I really want this gone as this is my first run and i am heavily invested in the build.
I really want this gone as this is my first run and i am heavily invested in the build.
PadawanWarrior
Well-Known Member
Get more fans and air blowing around to prevent it from happening next time.
Jorro
Member
Done and done. Thank you