Question
I have a potted magnolia approx 9ft tall with new growth and flower buds. I water it daily. Many of the leaves are turning yellow and falling off which I thought was normal. However, some develop large brown spots on them and some of the new growth has also developed this browning and will fall off. When you touch the brown areas they do not feel dry or crumbly. The pot is large(2'diam 3'ht). I'm confused as to whether I am overwatering, underwatering, or maybe needing fertilizer. I use an acidic fertilizer that I also use for azaleas and rhodies. I last fertilized 3 weeks ago. Any advise would be welcome.

Answer
Hi Sally

Magnolias are semi-evergreen and will lose leaves about twice a year.  This is normal.  The brown spots are most likely parasitic algae.  They can cause defoliation, but are usually on the lower leaves only.  Do a google search on parasitic algae on magnolia and see if this is what your tree has.  If so, I would treat with Hi-Yield Brand Copper Fungicide.  You will have to re-treat in 7-10 days.  I would also lay off the acidic fertilizer.  Magnolias like acid soil, but do not need it as low as azaleas.  I hope this helps fix the problem.  Good Luck.