[GPI]

Powdery mildew on Apple Trees.
by GPI

Plants affected
Apple trees, both edible and crab apple.

Season(s)
Spring
Summer
Autumn.

Signs and Symptoms.
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.

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

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

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

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

Mulch the watered soil to conserve moisture.

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

Cut out the badly affected shoots in early summer.

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

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

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.

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.

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

'Discovery'
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.

'Mother'
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.
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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