Rose Black Spot Is a Fungal Plant Disease
Definition
Rose black spot
A fungal disease of roses that makes purple or black spots on the leaves, which then turn yellow and drop early.
- Rose black spot is a fungal disease of roses.
- It causes purple or black spots to develop on the leaves.
- The affected leaves often turn yellow and drop off the plant early.
Key Idea
A fungal disease like rose black spot harms a plant mainly by reducing the leaf area available for photosynthesis.
Why It Harms the Plant
- Losing leaves leaves the plant with less surface for photosynthesis.
- With less photosynthesis, the plant makes less food and grows less well.
- As a result the plant produces fewer and poorer flowers.
Note
The fungal spores survive the winter on fallen leaves and stems, ready to infect new growth in spring.
How It Spreads and How to Treat It
Definition
Fungicide
A chemical used to kill the fungus that causes a fungal disease such as rose black spot.
- Rose black spot is spread in the environment by water and by wind.
- The spores are carried to healthy leaves, where they start new infections.
- It can be treated by spraying the plant with a fungicide.
- Removing and destroying the affected leaves also helps to stop it spreading.
Self review
- What type of pathogen causes rose black spot?
- What are the symptoms of rose black spot?
- Why does rose black spot reduce the growth of the plant?
- How is rose black spot spread?
- Give two ways to treat or control rose black spot.
