Tools you need to fight the mold
Start with a little section first.
Spray the wall with bleach starting from the top of the molded section down to the bottom. Repeat this step until the section is soaked with bleach.
Have water to clean eyes out if the wind changes Direction on you and the bleach goes into eye...be right back!
Ok I'm good now. Eye looks a little red, but that is maybe from the bottle of wine last night for dinner. Let's continue...
Notice the mold disappearing.
After about 5 minutes, take your garden hose and rise off excess dirt and mold.
Here is the finish result you should get.