wot are the disorders and diseases of the plant

For Tree Help website:

Magnolia may be subject to leaf spots caused by the bacterium Pseudomonas syringae or a large number of fungi. Leaf spots rarely require chemical controls. Rake up and dispose of infected leaves.

Canker diseases will kill branches. Cankers on branches can be pruned out. Keep trees healthy with regular fertilization and by watering in dry weather.

Verticillium wilt may cause death of a few branches or may kill the tree. Prune out dead branches and fertilize with high nitrogen fertilizer.

Scales of various types will infest twigs. Magnolia scale is the most common scale and can be one half inch across. Overwintering scales are controlled with dormant oil applied in the spring.