Powdery Mildew just ahead of harvest

[BillyBud0220]

Hey Folks, first time grower here in southern Maine. I have 3 very large plants, 9-12 feet tall, growing outdoors in the garden (unknown strain, seed from Jamaica). Looks like I have powdery mildew on the leaves (see pic). Flowers and buds are developing nicely and I hope to harvest in about 2 weeks. My question, is it necessary to try to spray these plants to control the PM? Is it too late to salvage? What should I do?

 

[Blew Hiller]

I never had PM...but I do wash my buds and I have seen other mentioning PM when they wash....I think they add Hydrogen Peroxide and it takes care of mildew. Let's wait to see what others say.

 

[Stunned]

@Jackalope would be a good one for this as he has gone through this before

 

[IGBG]

Being this late into flower I wouldn't be spraying anything on them other than alkalized water. And really that is all you need to kill off any type of mildew. Mildew can only root its self to other living organisms that metabolically live on the acidic side of the logarithmic scale. So if you simply spray your plant down with distilled water, that is pH'ed to pH 8.5, all the mildew on your plant will get killed off. But seeing you are so late into flowering, do it only on a sunny day, so your buds have a chance to fully dry out before dark, so you don't risk getting bud rot from any excess water from the spray-down getting trapped in your buds!

 

[Jackalope]

I used bleach water after the buds were formed. It worked indoors. That's a lot of PM to kill LOL. My plants were like 4' tall lol. PM will not ruin your buds in most cases.Treatment can if done wrong. PM will start to effect buds in extreme situations. It stay's on exposed areas of the plant. Over time it will start to effect the trim as the tips of the leaves on the buds will get it. Doesn't look like it is that bad yet but lots can happen in 2 weeks.

I use 1 1/2 tablespoons to 32 oz water. This controls PM without harming the buds. I started just trying to spray infected areas but found spraying the whole plant didn't hurt. Plus spraying the whole plant kills more of it. The bleach is all gone in a couple days and won't effect the buds. Spraying the whole plant would be a big job for you but it should work. The big question is do you need to do it.

With plants that big you are talking a lot of buds. You might be best just riding it out and washing your buds like has been mentioned. I just use water when I do it and I do it after I have trimmed them and they are ready to hang. Another big job when you are talking plants that size.

From what I can see. It looks like their are lots of white hairs on the bud behind the PM. Your 2 weeks might be a little soon. With that in mind you might consider spraying. Just do a branch and wait a day or 2. If all looks good then go a head and spray the rest of the plant. Going to need more then the spray bottle I use if you go that route LMAO. As was mentioned if you are going to spray do it on sunny days so everything evaporates.

Biggest thing. Don't panic.

 

[TorturedSoul]

Does anyone use a weak silicon solution for PM? I'm thinking its pH would be pretty high, but I might be misremembering.

 

[BillyBud0220]

Thanks everyone. I think I'll try a spray like Jackalope has suggested (and yes it'll be a big job but I really don't want to lose my first crop). I'll need a step ladder for sure.

 

[Rifleman]

I used low fat milk and sprayed the entire plant when I had PM. I've also used SNS 217. Both with success. The milk trick was passed on to me by SweetSue. If you don't treat it fast your harvest will be ruined. Whatever you use be sure to bud wash at harvest to remove any residue. I use 5 gal buckets with 4 gal water. First 2 buckets are warm water with 1/2 gal h2o2 & a cup of lemon juice added, rinse, dunk, swirl, repeat. The last 2 buckets are room temp h2o only and are used as final rinses. Hang to dry as usual. You'll be surprised how much garbage comes off your buds.

 

[BillyBud0220]

Thanks Rifleman, very helpful.