redirect specific category pages to subdomain

I have been trying this for a while but haven't found a solution yet.

I moved to wordpress and my old site is in custom CMS. the old site now goes to archive.example.com while all the new posts will be created on http://example.com

I have created different categories for new site so that it doesn't conflict with categories from old site.

I want all the request being made to old category pages to go to archive.exampmle.com

For eg:

http://example.com/apple should go to http://archive.example.com/appleAlso, all the URLs under apple category should go to the archive subdomain. For eg:http://example.com/apple/1234 should now go to http://archive.example.com/apple/1234

I tried this

RedirectMatch 301 /apple/ http://archive.example.com/apple/$1

but it doesen't work.