Black spot gets a foothold in the garden when leaves stay wet too long, or when a black spot-infected shrub comes into contact with another through crowding in the garden, infected leaves or canes lying in the planting bed, etc. It’s a problem in any climate, and is especially challenging for gardeners in areas with lots of rain or high humidity — the South, Midwest, etc.
Here are some things gardeners can do to keep this troublemaker away:
- use drip irrigation (a soaker hose) or a hand-held hose so that only the base of the Rose gets wet when you water, not the leaves.
- if that’s not an option, water early in the morning to give the moisture a chance to evaporate as the day warms up.
- don’t crowd Roses in the garden. I like the wild natural look myself, but Roses do best when their leaves don’t overlap with other plants a lot. And if black spot does develop, overlapping foliage will spread it like wildfire.
- by the same token, plant Roses in an open setting, rather than a close, confined area like a walled patio. Good air circulation goes a long way in preventing black spot.
- keep the area around Roses very clean and free of fallen leaves.
- Of course, a certain way to prevent black spot is to spray your Roses. There are many excellent black spot sprays that work not only before the fungus appears, but even after you have spotted a yellow leaf or two.