Chrysanthemums in Aberdeen
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UK Directory of
Common
 Chrysanthemum
Ailments

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Common Pests:
-
Aphids
- Thrips
- Leafminer
- Earwigs
- Slugs 
- Whitefly
- Capsid Bug
- Caterpillars
- Red Spider Mite
- Vine Weevil
- Sciarid Fly
- Stool Miner

Common diseases: 
- White Rust
- Verticillium Wilt
- Powdery Mildew
- Crown Gall
- Chrysanthemum Rust
- Botrytis

Common disorders:
- Nitrogen 
- Phosporus
- Potassium 
- Magnesium
- Manganese
Boron
- Copper
- Iron
- High Salt levels

Suggested settings:
- Monitor
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Date last updated: 
30 June 2008

 

Powdery Mildew (last updated 30 June 2008 )

Powdery Mildew is a fairly common seasonal disease affecting chrysanthemums. The disease manifests itself as a white powdery  covering on stems and leaves, occasionally on flowers.

Infection is typically first seen on the undersides of lower leaves but if left untreated it will spread to upper leaves. It is more commonly seen in a glasshouse environment but will occur outdoors in late summer. 

A few facts about powdery mildew:
Powdery mildews are a group of closely related species of fungi that are very similar in appearance, producing a 'powdery' effect on the surfaces of plants. 


Powdery mildew on leaves

Each species of powdery mildew has a limited host range, and powdery mildew on one species of plant will generally not spread to other unrelated plants.

All powdery mildews prefer dry conditions on closely spaced plants with poor air circulation and low light.

Low levels of fungal infection may show no symptoms but develop when conditions are favourable.

Powdery mildew spores are spread far and wide by wind currents.

Impact/effects on chrysanthemums
Leaves and stems become unsightly and leaves fail to photosynthesise to full potential resulting in a reduction in plant vigour and overall health. Plants may become distorted and premature leaf death may ultimately occur.

Controls 
As with other fungal diseases overcrowding and lack of ventilation will encourage the disease to spread so adequate room and good ventilation should be provided.

Fungicides available to the home gardener for powdery mildew control are based largely on two chemical ingredients - myclobutanil and penconazole. Sulphur applied as a dust is another form of control. 

There are numerous products available containing these chemical ingredients.  


Other information 

 

Website designed and published by Paul Barlow with input from Ivor Mace
Copyright 2008 Paul Barlow.