A fungal disease weakens the plant and can seriously reduce its flowering performance. The brown spots eventually grow together and develop grey centres. Infection is caused by air or water-borne spores entering the plant through damaged leaves. In wet weather the fungus spreads quickly. The spores are persistent and overwinter in the soil and on old leaves, stems and rhizomes.
Ugly brown speckles appear, merging to affect entire leaf in extreme cases.
Find it on
Healthy plants are less likely to succumb to an attack. Clear away leaf debris lying on the ground around the plants. Take care not to damage leaves and stems unnecessarily.