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Prevention of powdery mildew

Does anyone have any tips for preventing powdery mildew please? 
I always get it on my Ajuga and gave up on scabious and Knautia because of it.


  • KiliKili Posts: 971
    Apparently spraying with a 40% Milk and 60% water spray helps.

    "Using Milk for Plant Mildews

    More than 50 years ago, researchers in Canada discovered that milk sprays could help prevent powdery mildew on tomato and barley. Then the age of fungicides began, with no further published research on the milk cure until 1999. Since then, numerous small studies from around the world have validated the use of milk sprays on powdery mildew on a wide range of plants. Most recently, a spray made of 40% milk and 60% water was as effective as chemical fungicides in managing powdery mildew of pumpkins and cucumbers grown in mildew-prone Connecticut. In Australia, milk sprays have proven to be as effective as sulfur and synthetic chemicals in preventing powdery mildew on grapes. In New Zealand, milk did a top-rate job of suppressing powdery mildew in apples."


    'The power of accurate observation .... is commonly called cynicism by those that have not got it.

    George Bernard Shaw'

  • NollieNollie Girona, Catalunya, Northen Spain.Posts: 6,134
    Water, more water and yet more water 😃 Well, obviously not if you have boggy conditions or very water-retentive soil but it tends to strike here in hot, dry weather and I have managed to water plants out of it.
  • KiliKili Posts: 971
    Not so much here @Nollie. My Cucumbers are fed by wicking material and have access to all the water that need at all times but, I still have powdery mildew on them. Just trying the milk thing for first time but, fear its to late.

    'The power of accurate observation .... is commonly called cynicism by those that have not got it.

    George Bernard Shaw'

  • bertrand-mabelbertrand-mabel Posts: 1,787
    @Kili tried the milk treatment on our greenhouse grapes last year (first time ever to have mildew) and even after more treatments it didn't work. Have also taken on what @Nollie said about watering and have kept checking. Thankfully at the moment we are free.
  • alfharris8alfharris8 Posts: 333
    @Kili - thanks,  that's really interesting. 
  • BlueBirderBlueBirder Posts: 176
    I've also got powdery mildew on scabious and knautia. For the scabious, I regularly take out some of the older leaves, which helps air flow, and keep the plants adequately watered. I heard that overhead watering mid morning on dry days can help, as powdery mildew doesn't like the wet leaves. But not early morning or evening as then the leaves stay wet too long, and encourage other fungal pathogens. One definite thing I have noticed is intermittent watering makes plants much more susceptible. 
  • ObelixxObelixx Vendée, Western FrancePosts: 28,223
    We currently have a ban on watering between 8am and 8pm and, in anticipation of such bans, I installed seep hoses in the currant fruit cage, the courgette and squash bed, the two tomato beds and the dahlias and pumpkin bed which also has 3 clematis to disguise the wire mesh fence round the veg and cut flowers plot.  This last bed also gets all the used straw and poo from the chicken shed and that acts as feed and mulch.

    Over the week, each one gets a turn getting a good soak in the evening rotating over the week and, so far so good.  Plenty of moisture at the roots but none on the foliage except when/if it rains.

    I've also gathered all my nursery pots into a semi shaded spot, protected from the drying wind and strong sun on 3 sides and they get a regular watering from a sprinkler.

    I'll be buying some purin of prêle - marestail tea concentrate - to use just in case the courgettes get some mildew.  They're the most susceptible in my experience.
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
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