GardenForum - for everyone interested in gardening

If there's anything you want to know about gardening - get in touch

Pest Patrol

Clematis wilt

Introduction
Control
Physical damage

Introduction

Clematis wilt is the major disease of clematis and one that is feared by most clematis growers.

But first things first. Is your plant definitely suffering from clematis wilt? Most people who think they have this disease in their garden don't. It is always blamed when clematis wilt, which they can do for a number of reasons. Very few clematis cultivars are prone to the disease - it's only those that have been bred from a selected few species.

Plants with clematis wilt disease will suddenly completely collapse overnight - the foliage turns black (not brown) and the veins take on a purple colour. If those are the symptoms then the plant does indeed have clematis wilt. If not, then it's more likely to be physical damage to the stems.

Other diseases

Bacterial slime flux
Clematis mildew

Control

Affected stems should be cut down to ground level and the remaining stems and the surrounding soil sprayed with a fungicide such as Bayer Fungus Fighter (active ingredient myclobutanil) or Scotts FungusClear (penconazole).

Plants can be protected from further attacks by regular sprays in spring and early summer with the same chemicals.

Providing the clematis was planted deep enough (you should always bury the plant around 15cm (6in) deeper than it was growing in the pot), there will be plenty of underground buds to produce new stems.

Wilt is always worse on plants under stress, so it is vital to plant them in good soil (slightly alkaline, well-drained with plenty of added humus) and keep the soil moist during droughts; when in growth clematis need a minimum of 9-litres (2 gallons) of water per week. Heavy clay soils are the worst for clematis and an area measuring at least 1 square metre (square yard) should be thoroughly dug over and plenty of humus added before planting.

Physical damage

But most clematis plants wilt for other reasons, and here the foliage tends to turn brown rather than black, with no purple veining. This wilting can be due to:

The stems of clematis are brittle and can often twist and shatter in windy conditions. So it is vital they are strongly secured to their support. Plastic mesh (sold as clematis netting) is the best as there are plenty of places for the clematis to grab hold of, resulting in a strong hold and no twisting.
Slugs and snails and even earwigs or caterpillars will often chew through stems or even just remove the outer layers of stem again resulting in damage that leads to wilting.
Careless hoeing or weeding around the base of the stem can make wounds that will lead to wilting.

Placing a section of plastic pipe or a cut-up lemonade bottle at the base of the plant (sliding it over the stems to make a collar) will protect the stems from a careless hoe and slugs and snails (sprinkle a few slug pellets inside). It also shades the base of the plant which can also give some benefits.

If you want to know more, or there's a pest you're having problems with, then send an e-mail to: geoff@gardenforum.demon.co.uk

Problems with whitefly or vine weevil? Then turn to my whitefly control or vine weevil control pages.

Back to GardenForum Horticulture homepage