Best thing to treat fungus on natal plum?

[Hoosteady]

Any suggestions, organic, chemical, mechanical, whatever.... would be appreciated.

Thanks.

 

[Mac In Oak Ridge]

Mancozeb fungicide

 

[jackg]

Have found Neem oil to be okay for light work as an all purpose fungicide, miticide. insecticide. However have lots of landscape junipers infecting my quince, hawthorns and crabapple. Tried Spectricide. It seems to work quite well on the affected trees, however drift of the spray has hurt some of my maples.
Mac posted above Mancozeb, it is registerd for hawthorn and crabapple.