Saw-toothed hydrangea

Powdery mildews

What you will see

White powdery coating on leaves and shoots.

The source says: it is among the ornamental plants susceptible to powdery mildew.

How to protect

1. Prevention

   • open pruning, do not plant too densely
   • rake up and remove fallen leaves
2. By hand when presentremove affected parts
3. Gentle spray at the first symptomspotassium bicarbonate or horticultural oil (only for heavy infestation)
4. Chemical — only when nothing else helps as per the labelOnly if the damage is severe: a product authorised in your country against: powdery mildew.

Grey mould

What you will see

Soft, rotting parts covered in a fuzzy grey coating.

The source says: it is among the trees and shrubs susceptible to grey mould.

How to protect

1. Prevention

   • Keep things clean: remove dead and diseased parts.
2. By hand as soon as it appearsCarefully remove affected parts into a bag (spores spread easily) and dispose of them.

Leaf spots

What you will see

Brown to black spots on leaves; leaves turn yellow early.

The source says: on hydrangeas it is seldom severe enough to need spraying.

How to protect

1. Prevention

   • Remove old leaves before they infect the new season.
   • Do not wet the leaves when watering; keep the plant unstressed.
2. By hand after the first spots; in autumnRemove affected leaves at once and destroy them; collect fallen leaves in autumn.

Aphids

What you will see

Colonies of tiny insects on young shoots and under leaves, stunted and distorted growth, sticky honeydew and black sooty mould on it.

How to protect

1. Prevention

   • Tolerate a small number: aphids are food for beneficial insects.
   • Check plants often so you can act in time.
   • Encourage ladybirds, hoverflies, lacewings and parasitic wasps.
2. By hand as soon as you spot themSquash colonies with your fingers or remove affected shoot tips.
3. Biological before a heavy infestationIn a greenhouse you can buy in hoverfly larvae, lacewings and parasitic wasps.
4. Chemical — only when nothing else helps according to the product labelLast resort only: a product authorised in your country against aphids. Try non-chemical methods first.

Capsid bugs

What you will see

Ragged, distorted leaves with many small holes, dropped buds.

How to protect

1. Prevention

   • Tolerate the damage, plants usually recover; encourage birds and ground beetles.
2. BiologicalEncourage natural enemies.

Spider mites

What you will see

Leaves are speckled and bronzing, with fine webbing on the underside.

How to protect

1. Prevention

   • Reduce dust and water stress; do not use broad-spectrum insecticides, which cause mite outbreaks.
2. By handA strong jet of water on the underside of leaves.
3. Gentle sprayInsecticidal soap or oil, thoroughly on the undersides; only after mites are confirmed.

Vine weevil

What you will see

Adults notch the leaf edges; white larvae eat the roots, mainly in containers, and the plant wilts.

How to protect

1. Prevention

   • Check container plants often; look for notches on leaves.
2. By handCollect adults in the evening by torchlight; when repotting, remove larvae from the roots.

Scale insects

What you will see

Waxy scales on stems and leaves, sooty mould on honeydew.

How to protect

1. Prevention

   • Healthy plants tolerate low numbers of scale insects.
2. By handRemove adult scale insects and egg masses when visible.
3. BiologicalSteinernema feltiae nematode against soft scales (use with care, it may also affect other animals); encourage ladybirds and parasitic wasps.