Leaves magnolia trees turning black and yellow
Ann Asked
This is the second year for these trees. Both summers now they have started out beautifully in the spring and as summer progresses the leaves begin to turn black and yellow with black mottling and then they fall off. It’s not lack of moisture. We’ve treated them with a copper based treatment – not working. Any advice? Thank you!
The Gardener’s Answer
Hi, Ann: Magnolia virginiana ‘Henry Hicks’ is such a lovely tree and is quite disease-resistant. As with all plants, they are more prone to insect and disease issues when they are not given ideal growing conditions. I agree that it is not a moisture issue. The yellow foliage seems to be very random and is likely an environmental issue. Some of the lower foliage appears to have some leaf minor damage; I would need to see it closer to be certain. For a positive diagnosis and treatment options you can take samples to the horticulture agent at your County Cooperative Extension Service. The Fayette County offices are located at 1140 Hary Skyes Way. The phone number is (859) 257-5582. You can also have your soil tested here. These Magnolia trees require acidic soil and chlorosis can become an issue in alkaline soils.
