I am sorry for this delayed reply to your gardening question. We are transitioning to a new Q&A system and your question was unfortunately lost in the transition. I have discovered it now and hope this reply is not too late to be of help.
Your magnolia has various types of fungal organisms attacking its foliage. These are common especial following rainy periods and in spring when new grow starts to fill in and the older leaves begin to drop. There is little to do about it as the large rigid foliage of magnolias makes effective spray coverage impossible. It should not pose a major threat to your tree and should go away in time. Keep the tree adequately watered during summer droughts for a few more years while it establishes an extensive root system and fertilize lightly in spring and mid summer with a turf fertilizer at a rate of one cup per inch of trunk diameter. Spread the product evenly throughout an area one and a half times the new tree's branchspread. This fertilizing should only be needed for the first few years after planting your new tree.
Thanks for the question. Please stop in again soon!
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