It sounds like sooty mold, in which case you need to control the insects that are producing the honeydew that the mold grows on. Depending on which pest it is you can use a soap spray (preferably insecticidal soap made especially for plants because it's less likely to cause injury, but you can use a homemade soap spray) or an oil treatment. This article makes some suggestions for appropriate commercial oils but if you prefer home-made I'm sure someone can help with recipes. Do you know what pest is causing this?
Name: Tiffany purpleinopp Opp, AL @--`--,----- ๐น (Zone 8b)
Are there trees over your gardens? Are you in a temperate location where leaves will soon be lost anyway?
The golden rule: Do to others only that which you would have done to you.
๐๐๐ - SMILE! -โบ๐โปโฎ๐โโโฏ
The only way to succeed is to try!
๐ฃ๐ฆ๐๐ฏ๐พ๐บ๐ป๐ธ๐ผ๐น
The best time to plant a tree is 20 years ago. The 2nd best time is now. (-Unknown)
๐๐๐ฃ๐ก๐๐๐พ๐ฟ๐โฆโง๐๐๐ฝโโ โ๐๐
Try to be more valuable than a bad example.