Thorns among the roses

FUNGUS: GOOD RAINS HAVE BROUGHT PHENOMENAL GROWTH – BUT ALSO BLACK SPOTS

- Ludwig Taschner

The rainy weather over the festive season was the best Christmas present for the roses and their growth has been phenomenal.

But you may also have found black spots or splodges (where the spots have joined up) on some of the leaves. This is bad news for the roses and quick action is required.

Why do roses get black spot?

Black spot spores are always present in a garden. When they land on mature green leaves during a period of prolonged rain, they germinate and enter the leaves.

The leaves try to isolate the fungus by turning yellow around the black spot.

Once a leaf is full of black spots it turns completely yellow and drops off, causing the lower parts of a bush to become defoliated.

This disturbs the sap flow, so much so that the sap stands still and then heats during the sunny hours.

The heat generated effectively cooks the tissue from the inside and such stems turn black and die.

What to do