Speedwell Leaves Turning Black
I have four Speedwell/veronica Royal Candles in my garden. Two planted this year and two last year. After flowering, the leaves on all plants started turning black from the top down. Interestingly, the leaves on a pink variety of speedwell remain unaffected. I have since removed the affected leaves and new growth has emerged that so far is unaffected. Is this typical with this plant? It's been some years since I have had speedwell and I never remember them being affected? Any tips for control?