I found a solution:
To exclude all files and subdirectories add the ‘*’ wildcard to the .mpdignore file. You can use other wildcards in their normal fashion.
The previous post already explains how to do it. For example, to exclude all files in the folder /music/films, you would type at the command line:
echo "*" > /music/films/.mpdignore
posted for years here how to exclude folders from Library update - #2 by loza