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Powdery Mildew

Posted by Motezuma z5 WV (My Page) on
Wed, Jun 1, 05 at 22:25

Hey, everybody! Hope you all had a great day today. Or if not, that tomorrow you have a great day.

Now that you've had a little "white light" thrown your way, maybe you can help me with a problem...

I found some powdery mildew on streps someone sent me, and on an AV in another part of the house (yes, I am isolating the streps). Sadly, isolation doesn't work if you already have the problem you are isolating against... Anyhoozle, what can I do?

I was chatting with a web-buddy of mine and she happened to mention that she got some plants from "the source" (which will remain nameless) and they all had powdery mildew, which showed up on a slide under magnification, but not on the plants (at least in her house -the ones in the greenhouse DID exhibit the mildew). OK - she's a scientist! So I was keeping an eye on my plants from "the source" and today, I saw it!

I was disgusted, of course. Then I went to a friend's house, who had given me some AV leaves to put down, and whoa! all her AVs had it too. And she was like, oh, that wasn't there this morning... Uh-huh. But, bottom-lining it, what is the best way to deal with this?

Jon, Larry, et al, I know you are out there and can help me! And I'm very appreciative. And on pins and needles and mildew.

-Mo (WV)

Follow-Up Postings:

RE: Powdery Mildew

  • Posted by razz 6 Washington (My Page) on
    Thu, Jun 2, 05 at 8:05

I have heard of painting them with milk works.

RE: Powdery Mildew

  • Posted by Jon_D Northern Calif. (My Page) on
    Thu, Jun 2, 05 at 14:21

I never had a problem with mildew until lately. Now I have seen it on a number of different plants growing in different locations around the house, inside and outside. So, I am a bit of a beginner on this question too. In the past few years I have just used lysol aerosol spray on the foliage. It seemed to work. On a semperflorens begonia it stopped the mildew and by pruning back the affect leggy stems, I had a new crop of clean foliage that grew out and stayed nice for the rest of the summer.

But, this winter I had mildew on one sinningia (hirsuta) on my lightstand. It never seemed to affect the surrounding plants but it persisted on the hirsute leaves of hirsuta. I sprayed it with lysol, which seemed to work for several weeks, but then the mildew kept returning.

Now, I have read about the non-fungicide treatments like milk, baking soda, cinnamon, chamomile tea and a few others. I always joke that if they don't work on the mildew at least one can make cookies. But, I still need to figure out what I should actually do. It looks like I will need to add mildew to my list of pests that I treat. That seems to be what plant collecting is all about--a slowly growing personal list of pests that one gets, and must deal with.

I have had friends in the business of growing and selling mass numbers of gesneriads, AV's, orchids, and other plants, who regularly treated their greenhouse plants with fungicides. I never had that kind of large scale problem, but I guess it large crops it can be a more persistant pest than insects. i know that they can be very problematic on crops of AVs. I would suspect that you could try lysol, milk, etc. and then graduate to fungicides if the first line doesn't work at eliminating the mildew. Hopefully someone with more experience on treating mildew can pipe in.

I did learn from one friend that changing cultural practices alone is not enough. Once mildew infects a plant the mildew must be killed or it will keep coming back.

I just remembered that last year or so, we had a poster from New Zealand, on the begonia forum who posted photos of his tuberous begonias--just spectactular. He had a whole back yard of hundreds of plants all in full bloom. He swore by milk, as a spray to control mildew.

PS (and a note to myself): I haven't been over to the begonia forum lately. There might be some good info on mildew that I haven't seen.

RE: Powdery Mildew

Jon, I did know that milk was a possible treatment. Unfortunately, the scientist told me that there are some forms of mildew which are milk-resistant, and that "the source" has that kind. I think I'm going to try sulfur instead. Apparently you just paint it on the leaves and it kills on contact.

It's also possible for you to have the mildew on your plants and not see it. I don't know if it is unhealthy for those plants, but I imagine it would be.

I'll let you know after I try the sulfur.

-Mo (WV)

RE: Powdery Mildew

Putting my two cents in here! Hello you guys and girls. Have you tried Neem Oil? I mean faithfully used it? It really works. I use Dyna-Gro for pests, fungus and mildew I buy it online. I also have used Green Light Neem 11 with Pyretherins (hardware, nursery) with no damage to my plants or tiny babies. I have lots of plants and no Mildew since I have been using the Neem every two weeks. I mist them medium heavy, babies too. I keep a fan on all the time. Cooler Temps help too. My room is 69-70 degrees. Hope this helps. Some people don't like the smell of it but you get used to it.

RE: Powdery Mildew

  • Posted by Korina 9b, Sunset 17 (My Page) on
    Fri, Jun 3, 05 at 14:19

Ooo, I get -- or got -- powdery mildew on my Avs. Because of the geography of my office, my light stand really doesn't get much air circulation. However, ever since I mangled the giant Boston fern next to it and purchased a 4" fan from Target, everything seems happier. Fortunately I only have one p.m. magnet, and it's closest to the fan; it's looking much better. Lysol works wonders, but you
*will* lose all the flowers; it's better to just yank them off. Better a healthy plant that'll rebloom later.

Good luck.


RE: Powdery Mildew

One thing you need to do is get rid of the mildew as soon as it appears, otherwise it will produce spores and will pretty much take up permanent residence in your collection. I don't use chemicals (except fertilizer!) indoors but have rarely had problems with mildew. Clip off any leaf as soon as it shows signs of mildew. I grow mostly rhizomatous gesneriads so when mildew appears (always in the winter for me, and generally on certain susceptible plants--Gloxinia purpurascens is the worst but some kohlerias also get it) I cut back the affected plants severely, usually right to the ground.

RE: Powdery Mildew

I've only had powdery mildew show up in the last couple years, and only on certain cane begonias. (Kind of makes you wonder if there's a new strain out there, doesn't it?) So far the Gesneriads and Rex/rhizomatous begonias have been ok. I've used sulfur with some success, but it's always temporary. I think sulfur is a good mildew/fungus preventative when it's dusted on stressed plants or damaged tissues, but I'm not sure it's strong enough to be a successful cure once mildew is established. I've dusted it on and left it, literally for months, before cleaning it away, so it's not a matter of it not being on long enough. I suppose it's possible that it does cure the infection, but that the spores are in the air and re-infect the plant later on. I've Lysol-cleaned walls and shelves in the area, & don't know what else I can do. I really don't want to have a problem with all my potentially-vulnerable plants, and I'm seriously considering scrapping my affected begonias.
I really hope the sulfur works for you! Let us know.

RE: Powdery Mildew

Well, I tried the sulfur last night. It is messy as all get out! I tried brushing it off an AV, and forget it. Now it looks dusty as can be. I'm thinking of washing it. Next time I'm going to try Lysol.

I do have a couple of streps which I suspect of being infected, even though they don't display symptoms. The cut ends just keep withering, from the midrib out. So I cut them back to healthy tissue and dusted the cut ends with sulfur. They are not as messy-looking as the violet.

-Mo (WV)

RE: Powdery Mildew

I found some people swear by this.

Here is a link that might be useful: fung away

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