My magnolia tree's leaves are turning yellow and falling off. I have read the info here and apparently it is fungus. My question is, how do I treat a 30 ft tree?
Is the tree showing any other signs of disease? Do the leaves have any other signs of issues, spots, holes, dark edges?
Some yellowing of leaves is normal aging of a tree.
Watering issue, heavy rains or drought can cause yellowing of leaves.
Drastic temperature changes can also cause yellowing leaves.
Insects can be an issue, have you inspected the tree for signs of insects?
Inspect the underside of the leaves for pests, bumbs, chewing signs.
Pull back the mulch around the tree. Is the soil moist, dry, soggy?
Soil should be moist and dry slightly between watering or rainfall.
Nutrient issues can cause yellowing leaves. A soil test should be done to determine soil ph and nutrient levels.
The ph should be on the acidic side.
A neutral ph or alkaline soil can starve the tree of nutrients. Ph should be between 5.0 and 7.0
Do some investigating and began to rule out each possible cause.