What makes stems die back on roses?

Faced with pruning the roses, it is important to understand what makes stems die back on roses. Perhaps unsurprisingly it is referred to as rose dieback. And while you might think that it is always caused by a pest or disease, one contributory factor can be poor pruning.

Careful pruning to just above a bud is the key to helping the plant heal the wound and make healthy new growth. This is the case not only for roses, but for all woody shrubs. All poorly pruned woody stems can die back, but it is roses which regularly suffer from it, often with other contributory factors playing a part.

What is rose dieback?

Strictly speaking rose stem dieback is, as the name implies, the dying back of stems. This can be on just a short section of stem or branch, or in extreme cases the whole length pretty much down to the base.

In many instances, the die back will only affect one or two branches and the remainder of the plant may continue to grow and bloom. Where bushes are substantially weakened, growth may be much less vigorous and the demise of the rose can be a self-fulfilling prophecy.

Will rose dieback kill my rose bush?

Where the plant is very old or under stress for some reason, rose dieback can result in the death of the entire bush. In other severe instances, it can make the plant so weak that it produces thin stems and little in the way of flowers. Where this is the case, it is usually best to remove the plant as it is unlikely to recover.

If in doubt, it is worth cutting bushes hard back to around 6in. (15cm) above ground in the late winter or early spring. This ‘rejuvenation pruning’ will hopefully promote strong new shoots to be formed low down on the plant. And if the bush is already severely weakened, this will usually be enough to ‘see it off’. To be honest, if it is very weak, there is nothing that can done to bring the plant back from the brink anyway, so it’s worth a try!

What causes roses to die back?

Roses are most prone to dieback when they are in a weakened state. What makes stems die back on roses is often down to a number of contributory factors which conspire together. Pruning cuts can be one of the most common ways in which dieback starts either by causing physical damage to the tissues of the stem or by allowing fungal canker to enter the stem.

Cutting roses back during extreme weather can also be problematic and lead to dieback. In winter, pruning during very cold weather can allow frost to penetrate the cut ends and freeze the moisture in the cells causing them to burst. It is therefore best to prune during periods of mild weather in winter.

Meantime in very hot, dry weather during the summer, cutting into thick stems can leaves the cuts prone to rapid desiccation or drying. This also leads to stem dieback. In both cases, the stem will initially die back to a nodal point (the slightly swollen section of the stem where the buds are usually seen). However, the problem occurs when the death of the water-supplying vessels in the stem continues down, past the node or bud.

Can disease cause rose dieback?

In addition to physical damage, naturally occurring fungal or bacterial infections can get a foothold, feeding on the sugary sap in the stem. Such infections will cause the stem to die back more quickly and are only held at bay if the plant is in moderate to good health.

The healthy plant will be able to shut off the connections between vessels or cells, creating a barrier to further spread of the infection. Where the plant is already weak, it is much less like to prevent such spread.

Large pruning cuts and the crushing damage caused by using blunt secateurs are a common way in which stems can become infected.

How do you stop rose dieback?

The best way of lessening the risk of rose dieback is to keep the plants healthy. This involves maintain soil in the best condition by yearly applications of organic matter. This will provide good levels of nutrition to enable plants to heal and shrug off infections.

Feeding with a high potash fertiliser such as sulphate of potash or homemade comfrey feed will also help. The potash will toughen up the stems and leaves making them more resistant to pest and disease infestation. Avoid giving plants too much nitrogen fertiliser as this tends to produce soft, sappy growth which is most prone to infection.

Careful pruning is also needed, using sharp secateurs. Clean cuts, just above a bud – around 3-5mm – and made at the same angle at which the bud is pointing will minimise physical damage and give the plants the best chance to heal the cuts. There’s more advice on pruning bush roses here.

What can you spray to stop rose dieback?

While there is no chemical treatment specifically for rose dieback, spraying against fungal diseases can result in indirect benefits. Severe fungal infections can weaken a rose bush by reducing the leaf area and sapping the plant’s energy. However, before resorting to spraying there are a number of cultural and husbandry techniques to reduce blackspot, rose rust and powdery mildew – which are common problems on roses.

Does picking off leaves help reduce rose disease?

Picking off leaves that are badly infected with fungus, and collecting them once they fall off, will help to stop the spread of blackspot, rust and mildew on roses. Mulching the soil surface around the base of each rose plant, 2in. (5cm) deep and to around 12in. (30cm) from the main stem is recommended.

It is beneficial to do this in autumn and/or in late winter. This will help to feed the soil and cover up any fungal spores remaining on the soil surface. In turn, the latter will help prevent the heavy rain from splashing the fungal spores up to the roase stems and new growth to re-infest the plants.

For more reliable and trusted information on rose dieback see here.