Ask a Question forum: Downy and powdery mildew

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Name: Joanna
North Central Massachusetts (N (Zone 5b)
Life & gardens: make them beautiful
Million Pollinator Garden Challenge
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joannakat
Oct 2, 2017 12:24 PM CST
We've had a much cooler summer this year than I can recall in a long time. Perhaps due to this, I've had a lot more powdery and downy mildew than ever before. I'm in the process of removing the plants that have been struck--they're either annuals or deciduous so I'm not treating them, but I'm wondering if I should do something to the soil to prevent, or at least try to prevent it returning next season?

Is there anything that can be done now? All advice is welcome.

In case it's helpful, I live in north-central Massachusetts, zone 5b.
AKA Joey.
Name: Cindy
Hobart, IN zone 5
aka CindyMzone5
Celebrating Gardening: 2015 Plant Identifier
Shadegardener
Oct 3, 2017 7:07 AM CST
I've seen some mildewed plants here and we've been dry and hot. Dahlias, woodland phlox, Aquilegia. All I can think of doing is either cutting back affected foliage or trashing the annuals at the end of the season (which is coming very soon).
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize that we can't eat money. Cree proverb
Name: Joanna
North Central Massachusetts (N (Zone 5b)
Life & gardens: make them beautiful
Million Pollinator Garden Challenge
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joannakat
Oct 3, 2017 8:45 AM CST
Shadegardener said:I've seen some mildewed plants here and we've been dry and hot. Dahlias, woodland phlox, Aquilegia. All I can think of doing is either cutting back affected foliage or trashing the annuals at the end of the season (which is coming very soon).


Cindy, someone posted a similar video about using hydrogen peroxide. She said it works very, very well. Here's a link that explains the process:
https://www.hunker.com/1342714...

But I'd still like to do what I can to treat the soil now if at all possible. Anyone?
AKA Joey.
Name: Rj
Just S of the twin cities of M (Zone 4b)
Garden Ideas: Level 1 Plant Identifier Million Pollinator Garden Challenge
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crawgarden
Oct 3, 2017 9:08 AM CST
We have had a much cooler than normal summer, with much more rain than normal, I would have thought that the powdery mildew would have exploded; by this time of the year I normally expect to see my peonies covered with it. Virtually nothing, wondering if the cooler temps suppressed the growth of the fungus.
Keep Calm and Carry On
Name: Joanna
North Central Massachusetts (N (Zone 5b)
Life & gardens: make them beautiful
Million Pollinator Garden Challenge
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joannakat
Oct 3, 2017 9:49 AM CST
crawgarden said:We have had a much cooler than normal summer, with much more rain than normal, I would have thought that the powdery mildew would have exploded; by this time of the year I normally expect to see my peonies covered with it. Virtually nothing, wondering if the cooler temps suppressed the growth of the fungus.


Cool. Literally.

Did you do anything last season? To the soil or to the plants?

I didn't know peonies were prone to mildew.
AKA Joey.
Name: Charlie
Aurora, Ontario (Zone 5b)
Maintenance of Perennial Beds.
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SunnyBorders
Oct 3, 2017 9:57 AM CST
Re powdery mildew: have read that no part of the life cycle of powdery mildew involves the soil. Have also read that over-wintering of the dormant fungus occurs on infected buds and shoot tips.

Personally, with mixed perennial beds, I'm quick to cut out affected parts of plants, with most of the attention paid to the phlox and helenium which we have a lot of. I've also cut down all summer and fall blooming perennials to ground level by the end of our growing season and don't leave any plant detritus on the soil surface before winter.
Name: Joanna
North Central Massachusetts (N (Zone 5b)
Life & gardens: make them beautiful
Million Pollinator Garden Challenge
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joannakat
Oct 3, 2017 10:51 AM CST
SunnyBorders said:Re powdery mildew: have read that no part of the life cycle of powdery mildew involves the soil. Have also read that over-wintering of the dormant fungus occurs on infected buds and shoot tips.

Personally, with mixed perennial beds, I'm quick to cut out affected parts of plants, with most of the attention paid to the phlox and helenium which we have a lot of. I've also cut down all summer and fall blooming perennials to ground level by the end of our growing season and don't leave any plant detritus on the soil surface before winter.


Thanks Charlie. So does that mean that pulling up and trashing all the affected plants should do the job?
AKA Joey.
Name: Rj
Just S of the twin cities of M (Zone 4b)
Garden Ideas: Level 1 Plant Identifier Million Pollinator Garden Challenge
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crawgarden
Oct 3, 2017 12:03 PM CST
No, I do not do any sort of soil treatments, when I see the plant affected I cut the plant down to the ground and dispose of the infected plant material.
Keep Calm and Carry On
Name: Joanna
North Central Massachusetts (N (Zone 5b)
Life & gardens: make them beautiful
Million Pollinator Garden Challenge
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joannakat
Oct 3, 2017 12:39 PM CST
Thank You! !
AKA Joey.
Name: Charlie
Aurora, Ontario (Zone 5b)
Maintenance of Perennial Beds.
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SunnyBorders
Oct 3, 2017 2:41 PM CST
Joanna, I've never pulled up the affected perennials, although they do get to be divided periodically as needed.
I'm definitely assuming that it's enough just to cut affected perennials down to ground level and dispose of the plant material.
Has always worked for us, at least in our growing conditions here.

We don't use fungicides (or any other garden pesticides/herbicides) and don't need to use the safer (powdery mildew) home remedies you read about. Am a firm believer in the (Victorian!) concept of plant hygiene. Still I'd certainly agree that besides how one gardens, some plant problems are related to where one gardens.
Name: Joanna
North Central Massachusetts (N (Zone 5b)
Life & gardens: make them beautiful
Million Pollinator Garden Challenge
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joannakat
Oct 3, 2017 7:07 PM CST
SunnyBorders said:Joanna, I've never pulled up the affected perennials, although they do get to be divided periodically as needed.
I'm definitely assuming that it's enough just to cut affected perennials down to ground level and dispose of the plant material.
Has always worked for us, at least in our growing conditions here.

We don't use fungicides (or any other garden pesticides/herbicides) and don't need to use the safer (powdery mildew) home remedies you read about. Am a firm believer in the (Victorian!) concept of plant hygiene. Still I'd certainly agree that besides how one gardens, some plant problems are related to where one gardens.


My growing conditions should be similar to yours @SunnyBorders. But....plant hygiene? Huh? That's a new term for me. If you don't mind, can you please explain?
AKA Joey.
Name: Charlie
Aurora, Ontario (Zone 5b)
Maintenance of Perennial Beds.
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SunnyBorders
Oct 4, 2017 11:37 AM CST
I picked the term "garden hygiene" up from lectures on the history of gardening by David Tomlinson of Merlin's Hollow, Aurora, On. He was talking about the Victorian (formal) gardening in the UK. Because of the abysmal public health conditions at the beginning of the Victorian period, especially in central London, the Victorians mounted a huge and successful public health campaign (e.g. promoting the use of the new carbolic soap and crucially building modern sewer systems). David's point was that the Victorians extended this orientation to cleanliness to gardening. He also noted, however, that at that time gardening was a trade, in the same way that electrical and plumbing is now and notably that labour was cheap. So the large public and private estate gardens could employ teams of professional gardeners to maintain complex and beautifully manicured gardens.

In my usage, "plant hygiene" is about keeping the individual plants healthy. Exposing plants to sun, water, air flow and nutrients (all as required) is part of it, as is minimizing their exposure to pathogens. For instance, I'd guess healthy garden phlox plants can handle some exposure to powdery mildew spores (true some selections/cultivars more than others). I take my job to be to keep the growing conditions as optimal as possible.

Re the exposure to pathogens part: sometimes you see strong sentiments expressed on gardening sites, as to whether cutting back herbaceous perennials should be done before or after winter. I'd be the first to agree that how and where one gardens are relevant here; also that there's various things to consider. But I strongly believe that, at least with our closely packed and maintained mixed perennial beds and our climate, that fall cutting back results in a healthier environment for our varied perennials during their next growing season.
[Last edited by SunnyBorders - Oct 4, 2017 11:42 AM (+)]
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Name: Joanna
North Central Massachusetts (N (Zone 5b)
Life & gardens: make them beautiful
Million Pollinator Garden Challenge
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joannakat
Oct 4, 2017 11:46 AM CST
Thank You! @SunnyBorders

Very thought provoking. And interesting. Much appreciated.
AKA Joey.

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