Question
I have a Saucer Magnolia at the Northwest Corner of our property in Rehoboth Beach,DE.  Each spring, we get very nice blooms, then good foilage.  However, each of the past 2 years in late summer, the leaves have gotten what appears to  be some sort of fungus on them and the tree itself seems to get "scaley" stuff on it.  The leaves rot and fall off prematurely.

I've treated the tree with fungicide, but I don't think that I've solved the problem.

Any suggestions?

Thanks

Answer
Sounds like Magnolia scale, an insect. This small insect lives in a scale and sucks the plant juices from the tree. It deposits a sticky substance called honeydew and a fungus called sooty mold grows on the honeydew. To control the sooty mold you will have to control the scale. Here is a web link to information on the scale and its control.
http://ohioline.osu.edu/hyg-fact/2000/2003.html

Magnolia Scale: Apply horticultural spray oil as a dormant treatment. Crawlers may be managed with formulations of acephate, azadirachtin (Ornazin 3% EC only), buprofezin, carbaryl, chlorpyrifos (Dursban 50W only), cyfluthrin, cyfluthrin and imidacloprid, deltamethrin, dinotefuran, horticultural oil, hydrophobic extract of neem oil, imidacloprid, insecticidal soap, lambda-cyhalothrin (Battle GC, Demand CS, Scimitar CS, Scimitar GC, and Scimitar WP only), malathion, methidathion, and thiamethoxam. Marathon 1% G and Marathon 60 WP are labeled for use only on plants grown in containers, flats, benches, or beds.
Management Hints: Select and apply horticultural spray oil according to label directions. Adult females give birth to live crawlers during late August. Females may continue to produce young through September. Apply crawler sprays in late August and early September. Repeat applications may be necessary.