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Talk to me about mildew, please
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Posted by
flaurabunda 6a, Central IL (
My Page) on
Mon, May 28, 12 at 9:03
| You know how you read things here & file them in the back of your mind in the "Does not apply" folder? Well, I did that with powdery mildew. I had never witnessed it, or it was such a minor case that I ignored it and it went away.
Not this year. It's all over the place and I'm not so much concerned about what to do about it, but I'm wanting to re-open that file in my brain and stock it with more information.
Questions I have:
What are the conditions that lead to it?
Should I be more worried than I am?
Am I correct in assuming that when the weather takes another turn, as it obviously will, that the problem will end?
The roses look good overall except for the grey fuzziness near the terminal buds. Blooms haven't suffered and each rose's overall health seems unaffected. Location in the yard and type of mulch don't seem to matter. It's happening no matter where they are planted, how closely they are spaced, or what type of mulch they're resting in. |
Follow-Up Postings:
RE: Talk to me about mildew, please
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| As you suspect, it will stop spreading when the weather changes. Conditions for spreading are temperatures around 55-65 with very high relative humidity but no rain. These usually occur at night when the temperature drops to just above the dew point (creating the high relative humidity) and holds there for a few hours. PM conditions occur regularly on the Pacific coast where cool, moist air moves off the ocean every night. Morning fog with lows around 60 suggests that PM conditions are occurring. Rinsing the foliage early in the morning is one control measure. Spraying with 1 TB baking soda or 2 TB hort oil (or other oil)/gallon will kill existing PM |
RE: Talk to me about mildew, please
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| Okay; this makes sense. We are back into mild drought conditions again & when we were on vacation, I asked for only the pots to be watered. As a result, nobody was rinsed off for over a week and yep--conditions were prime overnight for it to form. |
RE: Talk to me about mildew, please
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| Michael - isn't that an "and" instead of an "or" for baking soda and oil? And be careful of the oil this time of year. If you're getting really hot sunny days you can get some leaf burn. Best bet is to spray when you know you'll have a handful of overcast days this time of year. |
RE: Talk to me about mildew, please
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| "Or," but "and" is OK if you have both. Other organic remedies that work are sulfur, potassium bicarbonate ("Remedy," "Kaligreen" etc.), and (people say) a 10% milk solution. |
RE: Talk to me about mildew, please
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| Because of the many other advantageous of using a silicate, I would suggest trying it first for mildew. |
Here is a link that might be useful: earlier thread
RE: Talk to me about mildew, please
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- Posted by simcan z5b/Toronto (My Page) on
Mon, May 28, 12 at 17:20
| I have never had a problem (occurrence) either but this year I was surprised to see it all over an old Bonica, three Lovely Fairy polyanthas and three Fairy polyanthas. It is not affecting a few HTs that were in the garden when I took over or my Betty Boop, Easy Does It, Julia Child, Lavaglut, Cinco de Mayo, Roseraie de L'Hay, Blanc Double de Coubert, or Iceberg. I was actually thinking I would just let it run its course but I am now planning on trying these remedies. |
RE: Talk to me about mildew, please
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| Antitranspirants such as Wilt Pruf also suppress active mildew, according to "Meg," a highly expert former poster. |
RE: Talk to me about mildew, please
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| I never had any luck at all with anti-transpirants. But also, neither Betty Boop of Iceberg ever mildewed here. Maybe, just as there are different strains of blackspot, there are also different strains of powdery mildew. Jeri |
RE: Talk to me about mildew, please
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| don't just wait for the weather to change because severe mildew can really weaken roses that suffer a long time with it. |
RE: Talk to me about mildew, please
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| I had awful PM this year. First we had a hot spell, then it became cool and damp. My Veilchenblau had it so bad, I lost half the bloom. Now that it's hot again, it's almost gone. |
RE: Talk to me about mildew, please
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I have had excellent results using milk, water and a little baking soda. Where i live big ole trees like maples, chestnuts etc get totally flocked with it.
I ended up with my huge chestnut tree just white with mildew -- and it was upwind from my roses. It spread mildew everywhere- to my cherry, lilacs, roses -- i even had the weeds behind my ac unit all covered in it.
I used the milk solution to kick it out of my rosebeds atleast. It's ugly but didnt really bother the rest.
Google powdery mildew and milk and you'll see plenty of recipes and discussions regarding skim milk or whole, organic or not etc.
I think i did 2 cups water, 1 cup milk (organic skim is what we keep in the refrig) and the soda amount was what they recommend if you make it with water.
It's worth a try since its so easy and safe- you can drink it- LOL.
My rockcress (aubrieta) grows this fuzzy mildew that literally billows off it when disturbed and i plan to try it on that thia year. (i read it was very effective in treating a peanut fungus like it). |
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