Dogwoods (Cornus), also known as horn bushes, are shrubs or small trees with not only colorful foliage in autumn, but also colored bark. The approximately 55 known species occur mainly in the temperate climates of the entire northern hemisphere and are considered to be very robust. Diseases and pests occur very rarely in the dogwood and often only as a result of an unsuitable location or incorrect care.

Brown leaves or spots on the leaves are often a sign of deficiency or disease

Anthracnose usually leads to death

Anthracnose, also known as leaf tan, is particularly dangerous here. It is caused by the harmful fungus Discula destructiva and occurs mainly after very rainy summers. An infestation is noticeable in the early stages by brown leaf tips and leaf spots and finally leads to necrosis on the shoots and twigs. If left untreated, this disease always leads to the death of the affected dogwood, with fungicides usually not helping. The only effective treatment method is a radical pruning of diseased parts of the plant far into the healthy wood.

prevent leaf tanning

However, you can prevent leaf tanning by following these rules:

  • Only carry out pruning measures in dry and sunny weather.
  • Always work only with sharp and disinfected cutting tools.
  • Always treat larger cuts with a wound sealant.
  • Water when it is very dry.
  • Never wet the leaves.
  • Avoid over-fertilization - especially with nitrogen.

Powdery mildew is easy to treat

The powdery mildew - also known as the "fair weather fungus" - occurs mainly in warm and sunny weather and is noticeable by a greasy, white-greyish fungal growth on leaves and shoots. Fortunately, this plant disease can be controlled very well, and not only fungicides have proven themselves. Alternatively, you can spray the dogwood with a 10:1 mixture of water (low in lime, but not necessarily rainwater!) and whole milk, repeating this for several days in a row. Affected plant parts should be cut away generously and disposed of with household waste.

Render mealybugs harmless with rapeseed oil

Mealybugs can often only be recognized when the whole horn bush is sticky and countless ants are gathering on it. The stubborn mini-animals suck off the leaf juice and excrete a sweet liquid called honeydew. It is controlled either biologically using parasitic wasps (€22.99) or earwigs - the natural enemies of mealybugs - or by regularly spraying the entire bush with rapeseed oil.

tips

Incidentally, the powdery mildew overwinters on the leaves that have fallen off in autumn, so that the fungus can attack the dogwood again in the following spring. You should therefore always rake up and dispose of all leaves after an infestation - of course not on the compost.

Category:

Trees