Hello Mitar. Ken here. IÃ¢â‚¬â„¢ve been looking at your picture of the magnolia
leaf for a few days now and it finally hit me. This looks like Shot Hole fungus.
The disease first appears in the spring as reddish, purplish, or brown spots. The
spots on young leaves have a light green or yellow margin and the centers fall out
as the leaves expand. The disease is most prevalent after warm, wet winters and
if the wetness continues into the spring. The spores are spread by splashing rain
or irrigation water. After leaf drop, inspect buds and twigs for varnishing and lesions.
Prune out infected tissue as soon as it appears. In severe cases a fungicide may be
necessary before the fall rains. I hope this helps. Good luck and take care
Ken here with The Home Depot in the Chicago area