Roses Look Terrific After Rain, but Beware of “Black Spot”

All around the region, roses are looking better than ever. The blooms seem bigger and the perfume on a sunny day is attracting bees galore.

No doubt this wonderful sight is due to the proliferation of rain that we’ve been receiving, but sadly it does come with a warning, namely “black spot”.

Black spot is a fungal disease characterised by the appearance of black circular spots over the leaves of affected roses. These affected leaves will eventually become yellow and fall off, and left untreated, black spot can cause a rose bush to completely defoliate.

Controlling black spot in roses requires a multi-faceted approach. Rather than treating the symptoms in isolation, a holistic approach at managing the disease will yield better results.

Consider the weather conditions

Many fungal diseases proliferate in warm and wet conditions, particularly if the leaf remains wet for extended periods. When you need to water, avoid overhead watering. Watering in the evening should also be avoided, as it allows moisture to remain on the foliage, creating ideal conditions for fungal spores to germinate and cause disease. Make sure there is good air circulation around your rose bushes.

Maintain good plant hygiene

Good sanitation is important to eliminate contamination by fungal disease. Remove and dispose of diseased leaves, including those on the ground, and put them in the rubbish, not the compost. Leaves left lying on the soil have the potential to pass fungal spores on to other roses.

Keep your roses healthy

Just like humans, the healthier your roses, the stronger their resistance to black spot. By improving the general vigour of your rose plants with generous applications of a specific rose fertiliser that includes potash, as well as improving the growing conditions, you can reduce, if not overcome, the incidence of pests and diseases.

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• Gardening