What are the Black Spot Roses?

What are the Black Spot Roses?

Black spot is a serious fungal disease on roses. It is specific to roses and primarily attacks the foliage but can sometimes also infect stems.

What are the symptoms of black spots?

Symptoms are irregular black spots on the leaves that become feathery or fringed with yellow margins. If left untreated, leaves will yellow and fall. This weakens the rose bush and if the disease spreads, will cause defoliation and eventually death.

This disease favours wet and humid conditions, occurring when water remains on the leaves for approximately 6-7 hours. Spores are spread by rain or water splash. The disease can be exacerbated if light and air flow is poor.

How to control black spots on roses

Control methods are to

• improve light and air flow
• ensuring plants are adequately spaced
• when pruning in winter, ensure you open the crown to allow light and air flow into the centre
• Avoid overhead watering or wetting the foliage as this encourages black spot

Winter jobs to control black spots on roses

In winter, rake up all diseased leaves (bag & bin) and prune back diseased stems to healthy wood with sterilized secateurs.

After pruning, spray stems with Eco-fungicide or Neem oil, continuing to spray throughout the season, especially if conditions are warm and humid.

The general rule of thumb is that a healthy plant is less susceptible to pest and disease attack.

To retain optimal plant health, feed roses regularly with Rose food, ensure soils are rich with compost, organic matter and manures and follow a consistent watering regime to the base of the plant.