By Marlee
New Zealand 
Our magnolia grandiflora looks like it is dying... leaves have gone all brown very quickly... we did have a very dry spell then last month plenty of rain.. we did trim some lower branches off early autumn...
10 Oct, 2015
Previous question
In a pot, or in the ground, Marlee?
If in the ground, have there been any heavy windstorms, lately? Roots may have been damaged by rocking--more common in young trees.
In the States, pocket gophers are a likely suspect, but I don't know if there is anything like that in New Zealand.
If the drainage is poor, prolonged heavy rain can drown the roots, which may be more susceptible to damage because of the previous drought.
13 Oct, 2015