Wednesday, 1 June 2011

Powdery mildew

Powdery mildew is a fungal disease that affects a wide variety of plants, particularly the cucurbits (squashes, cucumbers, marrows etc). Regrettably it seems to have got more common in recent years, and I have noticed several other bloggers in the UK writing about it recently.

This week I noticed an outbreak of powdery mildew on one of the sage cuttings growing in my garage. How the fungus got in there is anyone's guess. I thought these things would probably be wind-borne, and had therefore expected the garage to be a fairly safe place, but...

There's no mistaking powdery mildew - it looks exactly as if someone has sprinkled the plant with talcum powder.

I have treated this plant with a proprietary anti-fungal spray, so maybe it will survive, but I think I will try to isolate it to prevent further spread of the fungus. It is also said, by the way, that spraying plants with a mixture of milk and water can sometimes be effective in the early stages, so I might try that too.

One of the key aspects of preventing powdery mildew is good watering, since plants with excessively dry roots are more vulnerable. This is certainly something to watch with plants of the cucubit family, which have big leaves that sometimes make getting water to their roots more difficult than you would expect. [See my earlier blogpost called A deep thirst? for a way of overcoming this.]

There is a good article about powdery mildew, by Lucy Halliday, in the June edition of The Kitchen Garden magazine.


  1. It goes for my honeysuckle. So far. So good. Wish you hadn't mentioned it. It makes me nervous.


  2. Powdery mildew is a big pain in the vegetable butt. I always get it all over my pumpkin and zucchinis, and you know how big pumpkin vines get - it's impossible to spray all the leaves with just a teeny tiny spray bottle!

    I tried spraying with chamomile tea last year on some of the zucchini leaves, but I got lazy and didn't really keep it up. This year it is happening again, and I am not going to do anything. If things don't grow well for me, well then there are other things that will.

    In your face mildew!

  3. If the milk doesn't work you can try bicarb mixed with water and a little soap too. Usually I just give up and cut the offending leaves off as they become infected. Blasted stuff. :/

  4. We battle with it on our squashes too. I am going to try some of the remedies mentioned here. Will let you know if I have any success.

  5. Fortunately, it only hit my cucubits late in the season and they were on their way out anyway, so i didn't do anything. It must be a curse when it hits early.

  6. The worst plant we have for this is Michaelmas daisy and with plants that are towards the end of their life cycle. Is it early this year due to the dryness.

  7. I get powdery mildew on my tall phlox every year. Asters can be prown as well. I read an article recently that horsetail weed 'tea' is good at fighting fungal diseases. Horsetail seems to be taking over the countryside (near me anyways) so readily available. I have it on my 'to do' list.


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