Leaf spot disease
Please email info on rudbeckia. The leaves on mine turn black and now the flowers are dying before the end of the season. Thanks!
Hi Suzanne
A common leaf spot disease of Rudbeckia is caused by Septoria rudbeckiae a fungus that shows up in late summer as dark brown spots on the lower leaves. The lesions expand and spread to the upper leaves. Not much you can do but remove the diseased plant parts. Avoid overhead watering and provide more air circulation to crowded plants. You can spray with a fungicide to control the spread of the disease to new growth. Don’t let diseased plants winter over in the garden. In spring spray the plants with a fungicide such as Funginol, Bonide and in summer when you see signs of the disease spray again.
Another leaf spot disease is ANGULAR LEAF SPOT (bacteria). Spots are water-soaked and can spread to the entire leaf. Similar symptoms as above but requires a different treatment-a cooper-based bacteriacide (Bordeaux, Kocide). http://www.extension.umn.edu/yardandgarden/ygbriefs/p154rudbeckiadisease.html
Leaf spot disease
Please email info on rudbeckia. The leaves on mine turn black and now the flowers are dying before the end of the season. Thanks!