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Powdery Mildew on Apple Trees, Signs, Treat, Control.

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James Kilkelly
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Joined: 30 May 2006
Posts: 2173
Location: West of Ireland

PostPosted: Sun Apr 20, 2008 2:21 pm    Post subject: Powdery Mildew on Apple Trees, Signs, Treat, Control. Reply with quote

Powdery mildew on Apple Trees.
by GPI

Plants affected
Arrow Apple trees, both edible and crab apple.

Arrow Spring
Arrow Summer
Arrow Autumn.

Signs and Symptoms.
Arrow Powdery white fungal growth appearing as a dusting on leaves, tips of stems and buds. Eventually the foliage distorts, withers and dies.
See picture...

. Powdery Mildew as it appears on leaves, photo / picture / image.

Arrow Podosphaera leucotricha a fungus which thrives in warm weather/heavy night dews.

Organic or cultural control.
Arrow Space trees at recommended distances when planting to promote good air circulation. Your garden centre will advise.

Arrow Ensure you have good air circulation around the tree, by cutting back any surrounding planting if practicable.

Arrow Water the trees well, and don't let it become dried out totally between waterings.

Arrow Mulch the watered soil to conserve moisture.

Arrow If applying an artificial fertilser, you should select one specially designed for apple/fruit trees and its life stage. Ensuring the plant is well fed will help it resist diseases. Avoid at all costs high nitrogen fertilisers, as these encourage soft sappy growth that is more easily colonised by Powdery Mildew

Arrow Cut out the badly affected shoots in early summer.

Arrow Collect and destroy all fallen dead leaves that might harbor the fungus.

Arrow Whenever you prune established trees, you should leave the centre of the crown open to improve air circulation.

Arrow A garlic or onion spray may be applied before bud break to prevent the powdery mildew before it takes hold each season. Soak 10 grammes of crushed garlic or 15 grammes of crushed onions in a litre of water for a few hours, before applying by sprayer.

Arrow Experiments carried out in Switzerland have found that the roots of the common dock weed are effective in the control of powdery mildew. Mature dock roots were blended and mixed with water at the rate of 15 grammes per litre. Left to soak for an hour they were then sprayed on the foliage.

Arrow Grow only varieties labelled as resistant to powdery mildew wherever possible.See list below...

bright red, crisp, juicy; keeps longer than most earlies. Ornamental tree. Good, regular crops; partial tip bearer; Season: mid Aug.-Sept.

'James Grieve'
savoury, crisp to melting flesh; when cooked keeps shape, with juicy, delicate flavour. Good, regular crops; fruit bruises easily. requires well-drained soil. Season: Sept.-Oct. and longer.

'Lord Lambourne'
sweet, juicy, attractive flavour. Skin can become greasy when stored. Good, regular crops. Partial tip bearer; Season: late Sept.-Nov.

sweet, perfumed, distinctive flavour. Crops can be erratic, light; Season: Oct .-Dec.

'Peasgood's Nonsuch'
cooks to sweet, delicately flavoured purée; needs no or little extra sugar. Exhibition apple with large, handsome regular shape. Good, regular crops. Season: late Sept.-Dec.

'Worcester Pearmain'
intense strawberry flavour when well-ripened and scarlet. Tip bearer; heavy, regular crops. Season: late Sept.-Oct.

Other Control.
Arrow Spray with a fungicide containing the active ingredient myclobutanil such as Bayer Garden Systhane Fungus Fighter.

Associated content...
Powdery Mildew, How-to Video

Apple scab on Apple Trees, Signs, Treat, Control.

Any queries or comments on Powdery Mildew on Apple Trees, Signs, Treat, Control, please post below.

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Rank attained: Hawthorn Tree
Rank attained: Hawthorn Tree

Joined: 09 May 2010
Posts: 50
Location: Meath

PostPosted: Wed May 19, 2010 5:53 pm    Post subject: Any more information on the dock roots, please? Reply with quote

My eight year old son (a keen gardener) is the proud owner of a 20cm tall apple tree which he grew from a pip in science class two years ago. Variety: probably a Gala or a Pink Lady; lives in a pot on the patio. I don't normally have much of a mildew problem in my fruit and veg garden, but if I spot it, I implement a strict prune and burn policy. But as you'll understand, in this case there isn't very much to prune!

As we try to be environmentally friendly, we were interested to read about the dock root concoction, and ten days ago, we carefully dug out a piece of old root, mashed it, marinaded it and sprayed all fourteen apple leaves. We don't see much improvement yet, and we're not sure how many times or how frequently to spray. Can anyone give us further guidance?

Please don't recommend dumping the poor tree and buying a proper one - that's not the point. This is something he's grown for himself, and when you're only eight, that's very important to you!
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michael brenock
Rank attained: Chlorophyll for blood

Joined: 12 Aug 2008
Posts: 1275
Location: cork

PostPosted: Wed May 19, 2010 7:33 pm    Post subject: Reply with quote

while the seed may have come from a Pink lady or Gala the offspring is probably not one of these but a cross or a hybrid of these. Climatic conditions were obviously suitable for the development of powdery Mildew, warm and dry 9depends on how warm the garden is. I have never heard of the concoction you mention using Docks and it may have some merit. The affected leaves will not change but any new leaves should be free of the mildew. Water the tree and improve the ventilation. Make sure it is receiving adequate nutrition especially Potassium.
michael brenock horticultural advisor (retired)
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medieval knievel
Rank attained: Chlorophyll for blood

Joined: 03 Sep 2007
Posts: 1010

PostPosted: Wed May 19, 2010 8:47 pm    Post subject: Reply with quote

we had a cheap lidl or aldi tree, and we just kept nipping off the affected leaves and discarding them. the tree is now free of mildew, but it took well over a year.
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