Pests & Diseases That Affect Roses
Like most plants, roses can be affected by various pests and diseases – but don’t let that put you off growing them in your garden. Prevention is better than cure, and there are a few easy steps you can take to mitigate the likelihood of an attack. This guide will help you identify a range of pests and diseases and advise on the correct actions to take. These preventative measures and treatments will help keep your roses healthy for many years to come.
There are multiple pests that feed off rose plants, causing serious damage if left untreated. These creatures can include Aphids, Caterpillars, Leaf Rolling Sawfly, Deer, Rabbits, Red Spider Mite and Thrips. Traditional methods of controlling these pests such as spraying with insecticides are still the most popular option, although there are some more natural forms of pest control you could try which are much kinder to the environment.
Aphids are tiny insects, including greenfly, that multiply quickly on buds and young tender shoots – common pests. They leave a sticky residue on the stem or leaf called honeydew. Spray the plant with diluted washing up liquid on a cooler day and then wash the solution off after 15 minutes to avoid damaging the plant. Or if you can put up with them for a while, nature will restore balance as ladybirds, small birds and other predators consume them. As a last resort you could use an insecticide.
Caterpillars are part of the larvae family, and they love eating their way through plants. They munch on leaves with a giant appetite. Whilst they won’t kill your roses, they do leave bite marks and holes in the foliage and flowers petals. They may inflict short term harm, but they do feed the birds, and the leaves will be replaced in time. Remove them by hand when you see them, but be warned, they are great at hide and seek as they blend in incredibly well!
Leaf Rolling Sawfly
Rose leaf-rolling sawfly causes tightly rolled leaves on wild and cultivated roses, not to be mistaken with weedkiller damage! The rose leaf rolling sawfly lays her eggs on young foliage before injecting the leaves with a chemical that causes them to curl protectively around her eggs. No more than a week later, the eggs hatch into green caterpillars that begin eating what is left of the leaves, resulting in skeletonised foliage. Affected leaves should be picked off before the young caterpillar larvae have hatched and started to feed. Pesticides are unlikely to work.
Rose Slug Sawfly
The rose slug sawfly grazes on the underside of rose leaves causing them to turn brown and dry up. Damage from light infestations can be overcome and should not affect the vigour of the plants. Pick the larvae off by hand and try to encourage predators into your garden such as birds and ground beetles. If you are experiencing large numbers of larvae, you may want to consider spraying with organic pesticides.
Red Spider Mite
When spider mites are at work on your roses, it will look like they are covered in spider webs. This veil like webbing provides protection from predators for the mites and their eggs. The leaves will discolour and become limp and pale before falling. Spider mites normally appear in gardens because the use of insecticides has killed off their predators. They are sometimes hard to detect until the infestation has spiralled into large numbers. They thrive in warm, airless conditions, particularly in greenhouses or conservatories. The easiest solution is to move the plant outside and regularly spray it with water. The red spider mites should take a disliking to their new habitat and move on.
Rabbits are common garden pests who love feasting on rose bushes – they are not as innocent as they appear! Undeterred by thorns, young rabbits devour the new tender shoots that are within their reach, whereas older rabbits will even strip the plants of their bark and munch on the higher stems causing major destruction. Creating a fence around your roses with chicken wire is the easiest way to keep the bunnies out, although it is not the sightliest solution. There are chemicals which can be sprinkled the ground around the roses to help keep rabbits away too, but these are never completely effective.
In rural areas of the UK or if you reside near open countryside, you may find deer venturing into your garden in their search for food. Unfortunately, roses are one of their favourite things to eat as they consume the buds, blooms, foliage and even the thorny stems. The best way to keep them out of your garden, or at least away from your roses, is to erect perimeter fencing and netting. These need to be relatively tall and robust to stop the deer squeezing their way through it or jumping over it. Alternatively, hedges could be an effective barrier so long as they are tall and solid enough.
These tiny brownish yellow winged insects attack the foliage on a rose and can take over entire plant. They live in the buds and blooms of the roses, feeding on the sap within the petals. They can increase in numbers very quickly and can be a difficult pest to deal with.
Use an effective insecticide and try to control the infestation as quickly as possible.
Black spot is a common rose disease caused by a fungus that can do serious damage in a season. Easy to identify, round purplish or black spots usually develop on lower, old leaves. The leaf turns yellow around the spots and drops off. Normally seen from mid-July and throughout the summer months. If left untreated, plants become stunted and produce fewer flowers that are paler in colour and the plant may lose most of its foliage if severely infected.
Try to plant resistant varieties but if black spot does occur, remove the infected leaves to help increase ventilation, and prune the plants to keep the centres open. Use Sulphur Rose and a fungicide spray as a preventative measure and to control black spot effectively, even on resistant varieties. A regular wash with the hose is also recommended as this will wash the spores off the plant. To prevent reinfection the following year, collect up fallen leaves and burn them where possible. In Autumn/Spring, use a diluted disinfectant, such as Jeyes Fluid or similar, to drench around the plants as this will help to kill the spores living in the soil.
Orange coloured spots appear on the underside of old leaves in early summer. When rust is particularly severe, orange spore pustules will turn brown and then black, the leaves turn yellow and fall off. Rose rust will attack the whole plant apart from the roots and petals. This disease thrives in warm damp conditions and rust spores can lie dormant over winter on fallen leaves or in the soil. To treat, pick the infected leaves and burn them before spraying the plant with a fungicide. Gather up fallen leaves and wash the plant when it is in its dormant stage to avoid reinfection the following year. Start your spraying regime early and repeat regularly.
Rose canker often appears on the canes of rose bushes and is easy to identify easy. Look out for black splotches or gnarled, swollen lesions with dead and furling bark. Canker will usually show itself on mature plants with old wood where there has been exposed tissue from previous damage, rarely seen on younger well-tended roses. If canker appears on a stem which is expendable, simply remove it. However, it will often appear in awkward places that make it difficult to prune away. If you are desperate to keep the rose in your garden, cut away the damaged tissue with a sharp knife, carefully removing layers until only clean pith is left. Cover the scar to prevent further infections from entering. If the rose is not important, the easiest solution is to dig it up and burn it.