What causes black leaf spot? and is it serious or not?

Question

Have purchased some vinca minor (periwinkle) last week and they are in 4 inch cups. Have had them sitting on top of the ground and have been watering them every other day with a sprinkler.

Would the water being sprinkled on the leaves this past week have caused this?

if not what else would cause it and would they be okay being left untreated or not?

Thanks for your answers!

Answer 1

Yep its the watering. they dont need so much water !

Leave them alons and find something else to do

Answer 2

I am not positive but it could be they are getting sun burned as the water droplets do magnify somewhat.

Answer 3

If you are referring to black spot-it's hard to tell for sure without pictures, I know that it's a major fungi that affects roses.  It is spread by water that stays on the leaves so it's recommended to avoid splashing water. However in  your case, I've never heard of of vinca minor being affected. My recommendation would be to apply a sulfur based fungicide and apply it every week through it's growing season.  Good luck!