Last updated on October 23rd, 2023 at 08:42 pm
Many hobby gardeners have to deal with rose diseases and rose pests sooner or later. Here you can get an overview of the most common ones.
Roses are among the undisputed favorites of many hobby gardeners. However, despite suitable location and good care, even the most robust varieties are not completely resistant. There are many rose diseases and rose pests that can attack the plants. We’ll introduce you to the most common ones in the following sections.
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Rose diseases: The sooty mold
Star sooty mold, Latin Diplocarpon rosae, is considered the most common disease of roses. The fungus is very persistent and can cause great damage, so you should act as quickly as possible in the event of an infestation.
You can recognize diseased plants by their leaves: Star sooty mold causes brownish to black spots of varying sizes on them. The leaves eventually turn yellow and fall off. If you discover blackleg on your roses, you should cut off the affected leaves with a sharp knife. It is important to disinfect the tools afterwards so that you do not spread the fungus.
You can prevent the star sooty mold by strengthening your roses as a whole. This works, for example, with homemade pesticide. An example of this is horsetail broth.
Diseases of roses: Rose rust
A second common rose disease is rose rust. As the name suggests, this rose disease causes orange to reddish spots on the leaves of the plant. Rose rust spreads very well when there is moisture. You should therefore make sure that your roses are well ventilated. Firstly, you should not plant them too close together and secondly, you should thin them out regularly.
You should remove infested foliage as soon as possible so that the spores on it cannot spread. Also collect the fallen leaves on the ground.
Rose diseases: Powdery mildew
Powdery mildew can be divided into powdery mildew and downy mildew. Both diseases occur in roses, but powdery mildew is much more common. It is a fungal disease that usually becomes noticeable from summer onwards. You can recognize powdery mildew mainly by a whitish, floury coating on the top of the leaves of your roses. However, it can also occur on the flower stems, the buds and the flowers themselves. In doing so, it weakens the entire plant. If the infestation is severe, the rose will drop its leaves and grow less.
Against powdery mildew you can basically use fungicides for a quick success (more info: Pesticides: things to know about herbicides, fungicides and insecticides). Utopia advises against this, however, as such agents often not only combat the fungi, but also damage the plants in the immediate vicinity. Instead, you can simply cut off infested leaves with a knife and dispose of them.
Tip: Too much nitrogen promotes mildew infestation. Therefore, use fertilizers with a high nitrogen content only in moderation.
Rose pests: rose cicada
Unfortunately, roses have to contend not only with numerous diseases of roses, but also with a variety of pests. A well-known representative is the rose cicada. You can recognize an infestation by white speckles on the upper side of the leaves. On the undersides are the cicadas and their larvae.
The cicada overwinters as an egg in the bark of the rose shoots. Then, in May, the larvae hatch and develop into an adult about three millimeters in size by summer. The little animals are greenish in color and resemble grasshoppers in appearance. They harm roses by sucking the sap from the leaves.
You can prevent them by not controlling beneficial insects such as predatory beetles, leaf beetles, and spiders in your garden. You can also sprinkle some neem powder on the roses in spring and water them well. In case of an infestation, potash soaps, for example, will help.
Rose pests: rose aphids
Aphid is also a common pest of roses. There are many different species of aphids – roses are especially popular with the large rose aphid. The little animals are about three to four millimeters long and green. They sit on the young shoots, buds and leaves. The aphids secrete special excretions that damage the plants.
Although aphids can multiply explosively, you do not have to use ecologically harmful chemical preparations. You can easily remove aphids with environmentally friendly home remedies. Read also:
Rose pests: rose petal wasp
If you find large holes in the rose petals, it’s probably not a rose disease that’s causing it – it’s a pest. The rose petal wasp is shiny black and about five millimeters long. Beginning in early May, it flies through the garden and lays its eggs on the undersides of roses’ leaves between spring and summer. The larvae that hatch from them are the real problem. They are up to one centimeter in size and eat their way through the leaves. Sometimes only the skeleton of the leaf remains.
If you notice that your roses are infested, you should cut off affected shoots generously. You can prevent it by regular pruning in spring. Neem oil is also a suitable remedy for an infestation.
Rose pests: Thick-mouthed weevil
The thick-mouthed weevil is a nocturnal beetle that eats mainly the leaves of roses. The holes have the shape of a bay. While this looks unsightly, it is not dangerous to the plants per se. During the day, the beetles hide in the soil. They also lay their eggs there. The larvae of the thick-mouthed weevil that hatch from them are far more dangerous to the roses, because they damage the roots, disrupting water uptake.
The larvae can be controlled, for example, by nematodes (threadworms). These are available in specialized shops. There you can get advice on how exactly to apply them. Read more: How to get rid of the pest.
By the way: Even if you want to protect your flowers from rose diseases and rose pests, you should always consider: Ants can also harm roses, for example. But insects are also important for your garden – they are beneficial insects. You should never kill them with chemicals. First try to keep them out of the rose bed with home remedies. You can find tips here: Fighting ants: Natural home remedies for garden and home