E - you're gonna need a combination of endo and ecto mycorrhizae for maple. if you go to this website reforest.com/forestry_habitat_products.php (it's not the best website, i had some difficulty navigating around on it) they have just the thing. i think they're canadian or something, so they know what they're doing. they also ship internationally (got me my stuff here in germany)
good luck

Alan