Allow the mesh shirt to dry. Take the shirt outside and shake it vigorously to remove as much of the dried mud as possible. Large chunks of dried mud can be removed by carefully peeling them off with your fingers.
Fill a bucket with 1 quart of warm water. Add 1/2 teaspoon of dish-washing detergent and 1 tablespoon of ammonia. Stir the ingredients with a spoon to blend the solution.
Soak your mesh shirt in the ammonia and detergent solution for 15 minutes. Remove the shirt from the bucket. Rinse the shirt with warm water to remove loosened and softened mud.
Lay your mesh shirt on a flat work surface. Spray the remaining mud stains with an aerosol stain remover. Let the stain remover soak into the fabric for two to three minutes.
Launder your mesh shirt in warm water. Add heavy-duty laundry detergent and 1 cup of white distilled vinegar to the wash cycle to remove any last traces of mud stains.
Look over the mesh shirt before drying it. Make sure all mud stains have been removed. Treat any remaining stains by repeating Steps 3 through 5. Dry your mesh shirt according to directions on the care label.