Rosemary Plant has White Powder on Leaves

luckygardnrMay 14, 2007

My potted rosemary plant has developed white powder on its leaves. Is this bad? If so, what should I do about it?

Many thanks for any advice.

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Daisyduckworth(Aust)

It's a fungus called Powdery Mildew, or something similar. It is not good, but not always fatal.

Repot the rosemary, using fresh potting mix. Wash off all the dirt from the roots of the plant, then wash the entire plant in warm soapy water with a dash of bleach added. Treat the pot the same, and discard all the soil.

Once repotted, spray the plant with some chamomile tea, or some garlic spray. That will kill off any remaining fungal spores.

However, the very best treatment of all is to the put the plant into full sun. Preferably HOT sun, with lots of fresh air circulating around it. And water the plant less - it really is a moisture problem.

    Bookmark   May 14, 2007 at 6:34PM
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sherinyc

I have this problem as well. The rosemary is in a box containing mixed herbs (its neighbors are thyme, lovage, and mint). Will the fungus spread to the other herbs? Since it is so early in the season (I only planted the box a few weeks ago), can I pull the rosemary and just plant a new one? Or is the problem now in the soil?

    Bookmark   May 15, 2007 at 1:55PM
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Daisyduckworth(Aust)

Sheriinyc, yes, fungal diseases know no bounds, and the fungus will be in the soil.

Your mixture of herbs in the same pot won't work. Mint and lovage prefer moist soil, rosemary and thyme prefer dryer soil. And the mint will take over the whole lot. Keep it separate, in a large pot. I mean LARGE. Rosemary and lovage get large, too. Like the lovage can get to 2 metres (roughly 6ft). Not really suitable for a pot at all.

    Bookmark   May 15, 2007 at 8:02PM
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margowicz(8/9 UK)

Hi would it be ok to help these replacate the med by putting them near reptile light which produce heat and uv rather than just rely on N Irelands sun which ain't much at all the light is type in link

Here is a link that might be useful: light

    Bookmark   February 2, 2013 at 2:53PM
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flora_uk(SW UK 8/9)

spam??

If not, rosemary is a perfectly hardy common garden plant in NI and will be much happier outside in the garden than indoors.

    Bookmark   February 3, 2013 at 2:43PM
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margowicz(8/9 UK)

I had this problem with mine they hate load mositure I have a heatmat with mine to try replacte the med conditions this costs about 30p to run a week and I put mine out in day just so long as it ain't raining I do that once a week (no clorine in rain) I also let the base run bone dry before watering it..... they say clean the white off as much as possible and spray it with a garlic spray I done that but made my own clove garlic in spray water bottle gone now but it just been a week

    Bookmark   February 3, 2013 at 2:45PM
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flora_uk(SW UK 8/9)

Rosemary is perfectly happy out in the rain, margowicz. It could be outside all the year round in NI, providing it does not sit in water. You will not get powdery mildew, indeed, you are unlikely to get any pests or diseases, outside. Rosemary is an easy, hardy shrub in your climate. 30 pence is not much but it is a lot more than nothing which is what rosemary could be costing you.

    Bookmark   February 4, 2013 at 1:39PM
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margowicz(8/9 UK)

been reading a bit on this and seams to much attention is the main killer of this link below the heat mat is on for my snake so it isn't costing me really to keep it on keeps snake alive lol

Here is a link that might be useful: rosemary

    Bookmark   February 4, 2013 at 5:54PM
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margowicz(8/9 UK)

been reading a bit on this and seams to much attention is the main killer of this link below the heat mat is on for my snake so it isn't costing me really to keep it on keeps snake alive lol

Here is a link that might be useful: rosemary

    Bookmark   February 4, 2013 at 6:46PM
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flora_uk(SW UK 8/9)

margowicz - your link is to a website which I would not rely on since it is generic and not specific to our climate. It has factual errors too. The two suggestions I gave on your other post would help you more with growing in the British Isles. If you are really interested in herbs anything written by Jekka McVicar is worth reading, as is her website.

Here is a link that might be useful: Rosemary cultivars

    Bookmark   February 5, 2013 at 9:52AM
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