How To Deal With Black Spot Leaf Disease

Step 1: You will need

Step 2: Identify the disease

The symptoms of black spot are small round black patches, ranging from 1 millimetre to 1 centimetre, on the upper side of the leaf. The tissue around the spots turns yellow, and the leaves fall prematurely.

Step 3: Cultural control

As soon as you see any signs of black spot, remove the infected leaves with the secateurs or by hand. Gather all the debris from around the base of the plant too. Burn the leaves and debris or throw them away - never put them in the compost heap as this will spread the disease.

Do this throughout the year, whenever black spot occurs

Step 4: Chemical controls

Some gardeners use spray to control black spot. For the best results this should be applied after cultural controls, but may be an option if removing all the diseased leaves would leave your plant bare! Always follow the instructions on the spray container. Hold the bottle about 30 centimetres away from the plant and spray enough to coat the leaf, but not cause drips. Treat the plant either early or late in the day, so you don't spray pollen spreading insects like bees. Wait 14 days and then repeat.

Step 5: Prevention

Spraying can minimise spread but it won't stop blackspot all together. The healthier the plant, the less likely it is to catch the disease. To avoid blackspot in the future, keep your plants well-watered and fed.