When it rains a lot in summer, fungal pathogens feel extremely comfortable and spread quickly. Dahlias are also among their victims. Below you will find out which fungal diseases can affect you and how to treat them.
What fungal diseases occur on dahlias?
Fungal diseases such asGray mold,Leaf spot,Mildew,can occur on dahlias Stem rotandVerticillium wilt occur. In most cases, unfavorable weather conditions and an unsuitable location are the cause of an infection with fungal pathogens. Infected plant parts should be quickly removed and disposed of.
Which disease leaves a gray coating on dahlias?
A gray fungal coating on above-ground parts of plants is calledgray mold. Behind this is the fungal pathogen called Botrytis cinerea. Dahlias often suffer from this disease. It is favored by warm, humid weather. The affected shoots turn brown and eventually die. You should remove affected plant parts immediately so that the fungus does not spread to other plants.
Which fungus forms a mealy-white coating on dahlias?
ThePowdery mildew (Erysiphaceae) forms a mealy-white coating on the dahlia leaves. Initially only the top of the leaf is affected. Later the fungus spreads to the underside. It is favored by, among other things:
- planting too close
- too much fertilizer
- changeable weather
To combat powdery mildew, the dahlias should be treated with a spray. Net sulfur, for example, is a suitable agent. In addition, diseased plant parts should be removed and disposed of in the trash.
How does leaf spot manifest itself in dahlias?
Leaf spot disease is manifested byyellowish spots on the lower leaves of the dahlia. These spots quickly become larger and turn gray to brown. Eventually the leaves dry up and fall off. The disease is caused by a smut fungus called Entyloma dahliae. It likes to overwinter on the tubers and leaves of the dahlias.
What does verticillium wilt do to dahlias?
The verticillium wiltclogsthepipelines of the dahlia. This means the dahlia cannot absorb nutrients or water. The soil fungus is so aggressive that it can destroy the entire plant within a short time.
Is there a fungal pathogen that affects dahlia tubers?
Sclerotinia sclerotiorum is a fungus that causes sclerotina rot, also known as stem rot, on dahlia tubers. This often happens when storing dahlia tubers. If there is a warm and humid indoor climate in the winter quarters, this fungus is favored. It is noticeable through a white, cotton-like coating on the tubers. In growing dahlias it causes green to gray rot spots.
What factors promote fungal attack on dahlias?
Pestssuch as aphids, anunfavorable locationandincorrect care promote fungal infestation. These factors weaken the plant's defense system. Make sure to plant dahlias in an airy location. They should not be planted too close together. Mixed plantings with other perennials or grasses are also ideal. When watering, it is important not to water on the foliage, but directly into the root area. Furthermore, the infestation by pests should be contained.
Tip
Be careful of sooty mold caused by honeydew
Aphids contribute to the development of sooty mold fungi through their excretions in the form of honeydew. They are noticeable on the dahlias through a dark brown to black coating. Remove this coating to protect the dahlias from further damage!
