My Japenese Acers both green and red both have a mold growing up the stem
By Ktwist
United Kingdom 
my cats have used the pots they are in as a toilet and I have stopped this, the green acer's leaves are beginning to die
14 Jun, 2009
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I would empty out the soil/compost and re place it, give a good drink.
Some times the leaves on acers go brown at the edge and shrival up due to wind or and sun damage.
14 Jun, 2009