with
@Mieko2
the black spots are caused by a fungus .... perhaps from all the rain we have had + hot weather (not that far away)
a copper based fungicide will clear it up .........reapply after each rain ...remove leaves with the black spot
but the ants may be there for another reason ..... aphids .... the ants collect the honeydew that the aphids secrete ....
this honeydew is sticky ....and sometimes the honeydew will turn blackish
look your plant over ....especially under leaves near the stems ....aphids are tiny - little larger than the size of a pin head ...oval in shape ....and usually bright yellow but can be: black, brown, green or red
Control the aphids and you control the ants ..... use any insecticidal soap (containing fatty acids) will work killing off aphids
