Although delphinium is a flowering perennial that is very easy to care for, it is also very susceptible to e.g. for powdery mildew.
Larkspur is very susceptible to powdery mildew
What is powdery mildew?
Powdery mildew is caused by a fungus also known as the "fair weather fungus" because it is favored by heat, drought and strong sunlight. An infestation can be recognized by the white, mealy coating on the upper and lower sides of the leaves, shoots and flowers. The affected tissue turns brown and eventually dies.
Prevent and combat powdery mildew
If you don't want to spray with fungicides, biological measures sometimes help. However, since prevention is better than treatment, you can also spray the same preventively against powdery mildew. Brews made from field horsetail, sage or yarrow have proven particularly successful.
Spraying with field horsetail
In the summer, gather a few handfuls of horsetail and soak the herb in rainwater for a day. The ratio should be about 1.5 kilograms of horsetail to 10 liters of water. Then boil the whole thing for an hour, after which the broth is diluted in a ratio of 1:5. The broth has a preventive effect not only against powdery mildew, but also against rust, brown rot (on tomatoes) and other fungal diseases.
tips and tricks
Yarrow in particular has been used since ancient times to protect plants from fungal diseases. To do this, boil 500 grams of flowers in 10 liters of rainwater and then let the broth steep for three days.