Clematis wiltPhona clematidina, Ascochyta clematidina

Look for

Shoots, buds and leaves that are wilting and quickly dying back towards the roots, turning black as the plant dies. In some cases discoloured lesions can appear on stems.

Plants affected

• Clematis, especially varieties and cultivars that produce large blooms.

About

• Clematis wilt is a very common although little understood problem.
• The disease is caused by a fungus known as Phoma clematidina.
• The fungus causes lesions on the plant’s stems which in contact with water, release their spores that spread the infection.
• The disease is thought to also be affected by water-logging, wind and failed grafts.
• Sometimes clematis wilt is caused or aggravated by root damage and damage caused by slugs and insects, possibly transporting the spores.
• The disease is rarely fatal to the plant and new shoots normally reappear in the next season.
• Clematis wilt is often misdiagnosed because damage to the stems and lack of moisture at the roots causes wilting anyway.
• Critical points that define Clematis Wilt are: Leaves going black not brown; blackening from the top down; rapid onset.

Treatment

Chemical

Products containing the following chemical ingredients are all effective on Clematis wilt

• Myclobutanil
• Penconazole.

Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.

Organic

• Cut back affected stems to ground level
• Avoid plant stress by keeping the soil well fed and mulched.
• Plant more resistant varieties of clematis such as c. montana, C. viticella or C. tangutica.
• Plant Clematis deeply, around 6 inches lower than other plants. This encourages more bud development, so the plant can recover more easily if all the stems above ground need to be cut back.
• Put a shield around the base of the plants to stop infected water splashing up onto the base of the stems. The top of a fizzy drinks bottle is good for this.