The diseases of roses can be caused by fungi and pests. Pests and pathogens can occur everywhere and are independent of the growing conditions. If the resistance of the rose decreases, an infection can develop.
The resistance can decrease due to the following reasons:
- Nutrient deficiency
- Lack of irrigation
- Deterioration of soil structure
- Extreme weather conditions (frost, heat, humidity)
Roses are susceptible to diseases, and various pests and diseases can cause damage. The most effective ways to protect against these are by removing and destroying the infected parts and by spraying the plant with pesticides.
Diseases of Roses can include
This disease is caused by a type of fungus and can occur during warm, rainy weather, leading to the development of an infection. The fungus can overwinter in the buds and re-infect the flowers. A whitish, powdery coating forms on all parts of the rose. Infected parts need to be cut off and destroyed. Multiple applications of fungicidal sprays can be used to protect against it in spring.
This disease is caused by a type of fungus, and it appears as blackish spots on the leaves with a fringed edge. As a result, the leaves turn yellow and fall off. It can be controlled by spraying with a fungicide.
It is also caused by a type of fungus. Symptoms include orange spots appearing on the leaves and stems in spring, which then turn yellow and eventually black. The pathogen can overwinter on fallen leaves and stems, infecting the plant again in spring. The problem can be addressed with multiple applications of fungicidal sprays in spring.
This disease is also caused by a fungus. In this case, purplish spots appear on the flower petals. If it occurs during bud formation, it can lead to bud blight. It generally develops due to prolonged humid conditions. It can be controlled by spraying with a fungicide and by cutting off and destroying the infected parts.
Rose Diseases Caused by Pests
These pests attack the young shoot tips and leaves, sucking sap from the plant. As a result, the leaves turn yellow, deform, and fall off. Aphids produce honeydew as their excrement. In spring, they can be controlled by spraying with a cleansing or fungicidal solution. Planting lavender alongside roses can also be an effective remedy.
Rose Leaf-Rolling Sawfly
The cause of this damage is a sawfly that appears in late April or early May and lays its eggs on the edges of the leaves. As a result, the leaves roll up, and the larvae develop inside them, feeding on the leaves. This causes them to curl up in a tube-like shape, turn yellow, and fall off. Systemic insecticides can be used to protect against them.
This disease is also caused by a wasp that lays its eggs in the stems. As a result, the infected stems and leaves wither and die. Systemic insecticides can be used to protect against it.
It tends to appear during dry and hot summers. The leafhopper places its larvae on the undersides of the leaves, and they feed on the foliage, causing small yellowish spots to appear on the leaves. The larvae can also overwinter in the cracks of the stems, reinfesting the rose. In spring, they can be controlled by spraying with a cleansing solution followed by insecticidal sprays.
Rose Leafcutter Bee
This bee emerges in May and builds its nest for its offspring using leaves of roses (or wild grape, lilac, hawthorn). During this process, neatly cut sections are missing from the leaves. This bee is also beneficial as it contributes to pollination.
Western Flower Thrips
The thrips feed on the buds, flowers, and petals of roses. As a result, the edges of the petals turn brown, then wither, and severe infestations can cause bud distortion. Multiple applications of insecticidal sprays can be used to protect against them.
Prevention of Rose Diseases
To protect against diseases and pathogens, the primary approach is to purchase healthy, strong, disease-resistant, and virus-free rose plants. However, infections can also spread through the cutting of blooming plants, so it is advisable to burn the cut plant parts and disinfect pruning shears or rose clippers with disinfectants like bleach or other sanitizing agents. Paying attention to irrigation is also important as stagnant water underneath the rose can lead to fungal growth.
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