Clematis are fascinating climbing plants, known for their magnificent flowers. However, despite their rather uncomplicated care requirements, these plants can be affected by various fungal and viral diseases. Below we summarize the most common clematis diseases and provide detailed information on their detection and treatment.
Powdery mildew on clematis
Mildew caused by theErysiphe fungus, spreads by the wind and preferswarm temperatures and high humidity– typical conditions in summer and autumn. Unlike many fungal diseases, powdery mildew does not require moist conditions to spread.
Awhite or gray, dust-like coatingon the leaves is a typical sign of powdery mildew. In severe infections, leaves wilt and plant growth can be significantly affected.
To combat mildew shouldinfected plant parts removedand the clematis are thinned out regularly.Fungicidescan be used preventatively, especially in areas where mildew is common. Spray your clematis early in the season before symptoms become apparent and repeat applications every two weeks to keep the disease at bay.
Clematis-Which
By far the most common form is the so-calledPhoma-Whichthat through theFungus Asochyta clematidinais caused. It overwinters in the soil and on infected plant material. High humidity, warm temperatures and abundant rainfall promote the occurrence of the disease, usually in summer.
The Fusarium wiltsis caused by the fungus Coniothyrium clematidis-rectae. Mainly affects large-flowered clematis hybrids. The fungus penetrates the shoots, clogs the pathways and causes the leaves to wilt and die. You can find out more about itread this detailed article.
Brown to black lesions on leaves, which spread to and girdle the stems, are characteristic symptoms. Affected stems wilt quickly and die.
Early surveillance and prompt removal of infected stems are critical. Good air circulation through thinning and sufficient plant spacing help to prevent the disease. Fungicides can have a preventative effect, but must be suitable for clematis.
Clematis-Schleimfluss (Slime flux)
Clematis slime flow is onebacterial infection, which damages clematis plants. The disease leads to wilted foliage and afoul-smelling mucous secretion from the stems. Searhs.org.ukThe disease often occurs in spring and early summer.
Stem damage caused by frost, mechanical injuries or pests promote infection. Bacteria, which are normally harmless, invade injured stems and ferment the plant's sap.
There are no chemical treatment options, but pruning the affected parts of the plant can help. With a bit of luck, the plant will sprout again. If the infestation is severe, the plant can die.
Grauschimmel (Botrytis)
Gray horse kicksespecially with potted plants in greenhouses or winter gardenson. Clematis cultivated outdoors are affected less often. A flat, mouse-gray fungal lawn forms, which produces a lot of dust and spreads on leaves, flowers and shoots. Brown spots appear on leaves and shoots. The flowers do not open or fall off prematurely.
Root rot in clematis
Root rot, often due tofungal pathogens such as Phytophthora, Rhizoctonia, etccaused, usually occurs under conditions that are too wet, the result of overwatering or heavy rainfall.
The first signs arewilting and yellowing leaves. In advanced stages, the lower stems rot at the soil line. The roots are brown, soft and mushy.
Prevention is the best control against root rot. Avoid overwatering and ensure good air circulation. The soil should be slightly dry before watering again. A location with good drainage is also important.
Viruses in Clematis
Clematis can be affected by various viruses such asTomato Ringspot Virus (ToRSV)and thatGurken-Mosaik-Virus (CMV)be affected. These viruses are often transmitted by pests such as aphids or nematodes.
Symptoms of viral infections arewilted, stunted growthas well as yellow stripes, spots or mosaic patterns on the leaves, which often resemble a nutrient deficiency.
There is no cure for viral infections in clematis. However, infected plants can survive and recover in subsequent growing seasons. Avoid vegetative propagation of infected plants and sterilize cutting tools regularly.
Through careful care and preventive measures, many of these diseases can be avoided or at least contained. This will keep your clematis healthy and blooming.
Titelfoto: Shutterstock / Peter Turner Photography
