Hello everyone, first post here. I’m a new grower, on my 3 plant and have been struggling with powdery mildew. I’ve done some research and nothing seems to been making a difference. I’ve sprayed with neem oil and potassium bicarbonate on the past 2 and didn’t seem to like the way it affected the plant. It tool care of the PM but seemed too harsh. Further research suggested simply spraying a high ph water on the leaves but doesn’t seem as effective. So, I resulted to the neem/bicarbonate mixture but my question is, should I try rinsing it off this time? Any help is greatly appreciated, thanks!
Additional info:
2x4x5 grow tent
400 watt hps
Fox farm ocean forest soil and fox farm nutrient products
@Ekkos welcome to the grow community.
In addition to your solutions you’ve attempted do you have any air circulation? Exhaust vent, and a fan inside to circulate air around?
@Covertgrower hit the mechanicals; you gotta have LOTS of airflow and low humidity, depending on where you are. Assuming wpm is present that usually means in flower.
Pictures in natural light and a description of your setup: lights, tent, strains, soil, temps, RH etc.
Using straight 3% hydrogen peroxide as a foliar spray just before lights out will eliminate the wpm. Repeat every 5 days or so. Once you’ve knocked it back you can reduce the solution to 50/50 peroxide and distilled. You can spray this up until the day of flower. It’s also organic.
On the right is an unknown started from seed, in its tail end of 7th week of flower. Has lost a lot of foliage over the course lol. On the left is a clone of a clone GDP just starting her 4th week of flower. The original culprit was a Purple Mr nice clone that I had to harvest early due to the progression and got 54 grams of smokeable buds. The first GDP harvested even less but tasted much better because she was able to go the full cycle and had plenty of time to flush.
What I read in Jorge Cervantes indoor grow bible and other sources say to move lights away 30 minutes prior, reduce humidity, and not to spray within 4 hours of lights off. And I let it completely dry in front of fans before putting back under the lights
Well it’s all on how you want to proceed that’s your choice and I’m sure it works. If you leave under lights while still wet it can hurt them. I’m sure your way works as well all on how you feel better doing it.
That may be, but you won’t see very many advocates of that here. Spraying liquid just before lights out like supplemental foliar feeding reduces the risk of damaging the leaves. You HAVE to have lots of air flow and I would say the first indication you don’t have enough is…white powdery mildew. You probably won’t eliminate it entirely until harvest but you can knock it back to the point where you won’t see it and it won’t affect the plant’s performance.
Jorge Cervantes has a video on washing your harvest. I recommend that to everyone. It also uses peroxide and water. This will eliminate the wpm so you don’t end up smoking it.
What is your current RH? What is your current temperature range? Soil or media? What nutes if any? How often and with what do you water?
The air circulation was the first thing I addressed when I discovered the problem, added more fans. Daytime temp hits 80°F (high I know but don’t have burn) and humidity below 40% and “nighttime” swings low so I use a space heater to keep it around 69. When the lights go out I also have to reduce the inline fan to low otherwise the temperature drops too quickly.
Fox farms ocean forest soil and fox farms nutrients line. These 2 get the bloom nutes every other watering and the unknown pheno gets a booster every 3rd or 4th watering. I’m using filtered city water (until I install a RO system) and ph adjust to 6.5 at 72°
I hope I didn’t miss anything you asked! lol
Try a foliar spray containing mycorrhizae. If you treat once and don’t foliar feed after, your plant will be protected from all sorts of pathogens and baddies.
Are you sure it’s powdery mildew and not dried out chemicals on the leaves? Have you looked at it with a microscope of jewelers look. It would look like spider webs and not white spots. leaves also grow protective hairs (trichomes) even at an early stage.
Moisture on leaves for any considerable time under good light intensity will burn them. I believe anything you read suggesting foliar feed during lights on is because the plant absorbs better. My solution to this, don’t foliar feed, ever. Not since the very first time when I fried my leaves anyway.
Spraying for bugs or anything else can be done at lights out.
I only spray, if I have to, at lights out. I don’t foliar feed them either. On my outdoor plants I’ll spray them at dusk to prevent critters, but that’s about it. I’ve seen it cause more problems than help. Just my 2 cents
I have. Last year on my outdoor plants. My yard had a serious PM infestation, and my plants were 10 feet away from my yard.
I did a bit of Googling. I scrolled through several pages that talked strictly about controlling the environment, and of course H2O2 solutions. I needed a solid preventative, not a solution after the fact.
Then, a page came up directing me to AN’s Piranha, which I already have on hand. The page said it works well as a foliar spray to prevent mold/mildew/etc.
Then, I cross-checked that info, Re: using myco as a foliar preventative.
I ended up treating my plants’ leaves/stems/etc with a piranha/h2o spray. No molds. No issues.
Just blows my mind that people want to spray on aggresive species of bacteria, bacterial spores, and fungi(molds) onto their plants and buds to prevent other species of bacteria and molds. This is a practice banned by all legal states for a reason. APHIS (USDA) has a directive to all states to implement bacterial and mold testing of plant samples and have strict limits on such organisms and spores.
