Can someone tell me what is going wrong with this plant every summer? It always starts out great, then ends up with dying sections as in the picture. The plant next to it is also a daisy (second photo) and doesn't seem to have the same problems. I've done a garden drench with a product from the garden store (their advice), but it doesn't seem to help. Also, you'll see it has spots on it, which also seem to develop every year. I've been spraying with Bayer Natria Need Oil to keep the spots (rust?) down. Any advice or idea what is happening here? The plants around it don't seem to have this problem (Liatris, Rudbeckia, lilies).