Hi. I've had a fair amount of powdery mildew in the garden this year and whilst it doesn't seem to harm the plants I think it looks pretty unsightly. I've heard about the using a diluted milk spray but as full cream milk is not something any of us use in this house I was wondering about other organic alternatives. I see Suffolk Herbs are offering both green and yellow sulphur as an organic remedy. I'd be interested to hear your thoughts on and experiences of using this chemical. I'd also be interested to know the difference between the two colours - hopefully one smells less bad that the other! ;)
G xx
Georgie. As you know I am lacking in gardening experience ;D I do use yellow sulphur powder on geraniums to stop stem black rot (if that is how it is described) We had a lot of trouble with the rot but late husband read somewhere to use yellow sulphur. It seems to work 90% of the time. Hope you are well regards Lorna.
Hi Lorna. That's interesting but it doesn't really answer my question! ;) I've just sent you a PM btw regarding the Sage cuttings.
G xx
Apparently there are no fungicides for use on veggies. Organic control is by removing affected leaves, increasing air flow round plants and shrubs, esp fruit. Mulching and keeping veggies well watered is the RHS advice. The green and yellow sulphur I think is for flowers
I have heard that you can use bicarb of soda diluted and sprayed on - from someone working for a herb growing company.
Perhaps I should have made it clear I'm talking about flowers here, not veggies, I'd never use any chemicals on those.
The bicarb sounds interesting, Helen, any idea of the quantity of powder to water?
G xx
Sulphur is effective on cut wounds.
Bicarb does seem to check mildew growth - on cus - but don't know about flowers.
http://www.thewaterwisegarden.com/bicarb.htm
Thanks Tim, useful link. :)
I take it a bucket is 2 gallons?
G xx
Quote from: Georgie on October 26, 2005, 17:31:25
The bicarb sounds interesting, Helen, any idea of the quantity of powder to water?
G xx
Well, I'm not sure - I tried it (in fact I tried potassium bicarbonate!), about a teaspoon in a pint, but it was a couple of years ago, so can't really remember! (This was on ornamental plants). It did work !
I have just done a web search - 'bicarb of soda mildew plants' and lots came up! With lots of variations on the theme. Might be worth trying out a few different ideas.
I do agree with Wardy's comments about mulching, removing infected leaves, and thinning out to give good air flow. However, some plants are just prone to it (eg some Asters), and I think you have to decide whether to accept it, or remove the plants from the garden.
I thought we were talking veg. Sorry. On flowers peeps on our lotty use Roseclear for mildew but it's not organic and I think harmful to bees so has to be used late in the evening when they've gone to bed
Thanks Helen.  :)Â
Shalln't be using Roseclear then Wardy! Just wish someone could help out with the original question, mind!
G xx
Very often no organic remedies exist which is why the RHS probably recommends regular watering, mulching and getting air round the plants. Have a look at the RHS website and see what their advice is :)
Just buy 1 pint for full fat milk :) only about 50p so surely worth it ??
Well, the thing is, I was looking for a preventative, rather than a cure. I've already given up growing peas, asters and sweetpeas due to the problem but this year I got it on Polemonium and Verbena Bon. which I love. I'm afraid I won't waste water on perennials in the flower border but they are mulched every spring, are as well-spaced as anything can be in a small garden and I pick off affected leaves. I've had another look at Google and I think I might try the green sulphur but I'd still like to hear whether others have found it effective.
G xx
Well, I'll be interested in the results, as I get a fair bit of powdery mildew as well (I too try to avoid watering established plants in the garden), and I decide whether the flower is worth putting up with the mildew - eg there is one Aster (alma potsche) which has fantastic flowers, but looks a mess from mid summer on, but I just run my hand up the stem and take off all the withered leaves - looks leggy, but better than the mildew. Others, eg perenial cornflower, I try to dig out (it keeps coming back anyway!), as it always succumbs every year and ends up looking awful. I have quite a large garden, so can't really be too fussed with individual plants - as long as the overall effect is good, I'm mostly happy.
They use Roseclear on veggies on our lotties but it's not meant for that and it kills bees I hear :( I'd rather put up with the mildew :)
 I have been using bicarbonate of soda successfully for about 15 years to get rid of powdery mildew on melons (outdoors, covering about 1/2 ha.). I have also used it on a few other plants, including ornamentals, during this time. It works by changing the pH of the leaf surface so that the spores cannot germinate. I don't believe that there is any substance that will prevent powdery mildew, chemical or organic, so the best you can hope for is an eradicant once it appears.Â
 I would point out that here in the U.S. sulphur is not considered organic because it is so toxic to bees (it became "prohibited" about 20 years ago). Given that organic standards are fairly global I would be surprised if sulphur is considered truly organic in the U. K. either.
Thanks John, that's really interesting.  :)
According to HDRA, (or Garden Organic as they are now called), 'although sulphur is acceptable under organic regulations, for the control of powdery mildew, it is a powerful chemical which is not harmless in the environment. Safer's Garden Fungicide, and a puffer pack of sulphur, are both available from The Organic Gardening Catalogue. Follow the manufacturer's instructions. Some varieties of plant may be damaged by sulphur, such as the apple 'Cox's Orange Pippin'. If you are unsure, spray an isolated leaf or shoot, and watch for scorching or leaf-fall within 24 hours'.Â
Jenny has also offered some advice over on the Powdery Mildew thread in Pests and Diseases.
I think I'm inclined to go with the bicarb option now.
G xx
When using any substance you should do a small test application first on all the plants you wish to spray. With bicarb., and many other organics a spreader needs to be added (for convenience many properiatary compounds will have the spreader already incorporated), with dishwashing liquid generally being used. Many plants have sensitivity to this as it's surfactant qualities can break down the oils on the plant leaves and consequent rupturing of the cells, especially if applied in strong sunshine. I am able to using dishwashing liquid on fuchsias for whitefly control but only if I spray at dusk.
Oh, I'll be using soft soap, John. No idea what's in most washing up liquid but I'd guess it's not organic.
G xx