So far just in the back yard and also so far only the Lemon Balm and Chrysanthemums are heavily affected and are dying or at least dying back because of it. This is it on the Lemon Balm... What is it and how do I treat it? ( photo / image / picture from toni's Garden )
Hiyah Toni, I have to rush out of the house now...but at first glance, I would be inclined to suspect an insect. Have you checked the underside of these leaves? Can you show the underside of these leaves in a piccie? Is there any stem involvement? It is an interesting thing. I mught be temped to lop all the leaves off halfway down the stems. The plant will probably keep right on growing. I cut off my lemon balm three times a year for the compost. Good luck, I gots to go, but will return after the field work. Seeyah.
No stem involvement and on closer inspection I found that the spots are transparent. Underside of Lemon Balm ( photo / image / picture from toni's Garden ) Another plant involved ( photo / image / picture from toni's Garden ) Even though the spots look a different color on the Chrysanthemum the result is the same as on the Lemon Balm. Chrysanthemum ( photo / image / picture from toni's Garden )
Toni, I think you have two different issues. The first one, I agree with Sjoerd, is insect damage. I had my Japanese Anemones looking like that last spring and I found black insects with a red stripe on them at the edge of the wing, I am sorry I can't remember what they were called, I sprinkled them w/ sevin and they "went away". Cut back the damaged plants and let new growth come back in in it's place. The chrysanthemum looks like a fungal disease to me. Try a baking soda spray (1t. to 1 qt. of water and a dab of dish soap) or cut them back, also and spray them as soon as the new foliage starts coming in.
Hi Toni--for me, the fact that the little places on the lemon balm leaves are indeed transparent indicates insect damage. I have seen the same on some of my plants. As Carolyn has said, the chrys. plant damage looks a bit fungal to me, but I really can't see the leaves well enough to have a strong opinion. I wonder if you could perhaps make more fotos , showing close-ups of leaves top and underside. Has it been a bit moist there this spring? Has it been cool or hot? My impression is that the chrys. plants probably have a fungal insult, but I have noticed that red spider mite can also make similar places on leaves as do dome aphid sorts. I am intrigued.
Do they start out as yellow spots and then turn brown or black? Could be Septoria chrysanthemi. Jerry
