I am hoping that I can get some good advice here. In the garden I work at there is a Magnolia grandiflora that appears to be struggling, and I have not been able to figure out what the problem is. The tree is about twenty years old, twenty feet tall, 10" DBH. For the past few months the foliage at the top of the tree has been yellowing and thinning out. Until recently, I was not able to identify any insect pests at all on the tree. In the past week several of the small lower branches have been attacked by twig borers, but this may be due to the overall low vigor of the tree. The tree is growing in acidic, well drained soil, in a high rainfall area. Soil organic matter is relatively low, as is typical of the moist tropics. I have not yet done a root excavation, however all surface roots appear to healthy, and there are no above ground signs of girdling roots (i.e. flat surfaces on the lower trunk). The tree is currently flowering, and I was planning on waiting until this was done to see how much of a growth spurt it put on before I considered a root inspection.
We would very much like to save this tree. It is an 'Andrew Jackson' cultivar, and is a cutting from the tree at the White House. If any of the arborists from the southern states have any experience with magnolias, or if anyone can give me advice on my diagnostic process, I would very much appreciate it. Thanks.
I'll try to post some pictures.
We would very much like to save this tree. It is an 'Andrew Jackson' cultivar, and is a cutting from the tree at the White House. If any of the arborists from the southern states have any experience with magnolias, or if anyone can give me advice on my diagnostic process, I would very much appreciate it. Thanks.
I'll try to post some pictures.
