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Would air circulation help prevent powdery mildew?

Posted by quinnfyre z7 PA (My Page) on
Sun, May 31, 09 at 23:56

It occurred to me that maybe I've been getting powdery mildew outbreaks during the winter because of a lack of air circulation... does this sound right? Does anyone run a fan where they grow their AVs? I'm getting tired of losing plants during the winter, or trying to coddle plants to pick up once it's spring. The reason I have this theory is that the worst offenders are always on the middle shelf. I have two white mesh stacking shelves, locked together to make three tiers, and the middle part of this is where I grow semiminis. All of the ones I grew on that shelf succumbed to powdery mildew, and spraying Lysol helped temporarily but they'd just get it again. The other parts of the shelves are fine. I decided to run a fan on low speed now, and hopefully that will help, but I was wondering what others think of this plan? It would be great to get my plants to live longer than a year, it's disheartening to get plants mature enough to bloom only to lose them within 6 months. Luckily I started leaves of all of them this past summer/fall, and the babies are pretty big now. Also happily, the plants on the other parts of the shelves are doing well. Just gotta get those semiminis to stick around.


Follow-Up Postings:

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RE: Would air circulation help prevent powdery mildew?

quinn,

You are absolutely correct in your assumption. Lack of air circulation is a major contributing factor in violets, and other plants for that matter, getting powdery mildew. I run small fans around all of my violets. It has really helped keeping PW under control for me.

Larry


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RE: Would air circulation help prevent powdery mildew?

I 2nd Larry :)

I also took a 3 parts hot water: 1 part beach solution and wiped everything down to remove any spores that might be trying to take up residence.

Once Nancy and Barbara told me that it was ok to give a Lysol mist every once in a while, I do that about once a month and along with my ceiling fan that I run 24/7, (knock on wood) I haven't had any problems with PM anymore.

Interestingy enough, I've never had it with any of my standards....only minis and semis.

Dora


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RE: Would air circulation help prevent powdery mildew?

Oil sprays work really well to control powdery mildew. Add 3 tbsp of mineral oil to 1 gallon of water containing 1/2 tsp of detergent soap. Mix well and shake spray bottle constantly while in the process of application to keep it mixed up.


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RE: Would air circulation help prevent powdery mildew?

I've had my share of powdery mildew. I never think about it till I get it. I use neem oil. Seems to 'control' it. Think I'll try a more preventative measure, fans and Dora, your 3 parts hot water, 1 part bleach solution and wipe everything down sounds good. (everything includes leaves, right)? I'll do that, then spray with the neem oil. I like neem oil since it keeps the spores from flying around to your other plants. I would think if you have the fans on while you have an outbreak of PM it could spread it even more? Someone told me during the cool and wet months if you grow by lights turn them on at night instead of day to raise the night time temp. I was just out of town a few days several weeks ago when we had a cold snap, came back and a couple of my plants had it. ARRRGH. They were just blooming again since I had re potted (severely) and cut off blooms. I found two with PM but went ahead and treated all of them. Blooms came back pretty quick this time;) I'm sure I've read on here of some fungal spray but haven't ordered it yet. Good Luck.


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RE: Would air circulation help prevent powdery mildew?

Aha - just sprayed mine this morning before work. It is this time of the year - the heater is off - and the nights are still cool. I turned the lights to go on at night to prevent the plant room from going too low.

I got a fan with an air ionizer. Going to ionize the PM spores... Anybody tried it?

Irina


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RE: Would air circulation help prevent powdery mildew?

Thanks for the feedback. I'm glad the consensus is that this will help. The real test will be January through February. If they all make it through then without getting major outbreaks, I'll be ecstatic.

I don't have an outbreak of powdery mildew anymore, all those semiminis on the middle shelf are done for : ( I Lysol'ed the surfaces before putting anything else up there, and kept the replacement babies bagged for a few weeks before setting them free late last week. Looking good so far. Just started using the fan a couple days ago.

Curious... why would running a fan at night when the lights are off raise the night time temp? Currently I am only able to run my fan at the same time the lights for my orchids are on, because the only plug I have access to is attached to the timer. However, the lights are on for something like 16hrs a day.

I have no idea what ionizing PM spores would do. Please keep us updated!


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RE: Would air circulation help prevent powdery mildew?

Dora,

I agree with you. Semi's and mini's seem to get it worse. I grow a lot of miniature trailers and they are the hardest hit during PM season.

Larry


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RE: Would air circulation help prevent powdery mildew?

Quinn -

I turned the lights on at night, not fan ;-)). Actually I programmed them - 6 hours in -6 out -6 in 6 out. There is a theory that plants accummulate energy at the day time - and grow at the nighttime. So some greenhouses increase - on off frequency - to deceive the plants to grow faster. I do not know if it works - but somebody sure made a PhD on it.

Irina


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RE: Would air circulation help prevent powdery mildew?

Ah, I see, that makes more sense. Reading that line again, I notice that it probably was referring to the lights, not the fan. Hmmm, interesting theory. I don't have AVs under lights, for the most part, mainly orchids, and a lot of those are night fragrant. So I'm guessing I'd just confuse them if I did that. Still, might be a fun experiment sometime. I do have multiple babies of a bunch of different AVs. I could set one up under steady lights, and one under cycled lights. Well, that is, if I had a spare outlet. I'll keep it in mind, for when I rearrange things again.


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RE: Would air circulation help prevent powdery mildew?

Quinn -

the amount of the starters you have on your window... I would say the shelving unit is coming.

;-)) Irina


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RE: Would air circulation help prevent powdery mildew?

Ha, that is already a shelving unit in front of my window. In fact, both of my windows have a shelving unit in front of them. There is a bit of room on the top usable shelves of each, but it's not ideal because the angle of light coming through there is not great. At least most of the starters on the main part of my shelf are semiminis. The shelf below, though... all standards. Yikes. Also, I have more leaves started that are standards that haven't gotten babies big enough to be on these shelves yet. Looks like I'll be taking over more of the house. Eeep.


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