Star Magnolia Bush Problems?

I have a Star Magnolia bush, installed 3 years ago, and there are entire branches were the leaves are drying out and turning brown. It has not been abnormally hot or dry. This has not happened before. Any ideas.



I have been pulling the leaves off, but not the branches, as they are still green inside.



Thanks.
Star Magnolia Bush Problems?
Star Magnolia are quite pest free, though they can be affected by several problems. One problem common to Star Magnolia is root girdling (circling roots). Though this could be your problem, the symptoms you describe do not exactly fit.



Sometimes Star Magnolia can be infected with a canker. This fungal infestation causes dark sunken areas on the stems and branches, eventually girdling the stem and branch and results in death of the stem or branch. Look for these darken sunken areas on the branched affected on your tree.



Another possibility is verticillium wilt. This soil borne fungal disease enters the roots and propagates in the vascular system of the tree. A common symptom is leaves will start to brown on whole branches. If you have verticllium wilt, you should be able to see a light- to dark-green streaking of the sapwood when viewed on an infected branch with the bark peeled away. If the branch or plant is cut and the cross section examined, the discoloration may appear as a ring. The vascular discoloring often occurs with the advance of the fungus or the fungal spores through the sapwood except sometimes in the early stages of infection.



Although some plants may die quickly, more commonly it takes one or more years to die. Trees and shrubs with only a few wilted branches during a growing season may become more severely infected the following year. Some may recover and show no more symptoms in the following years. In other cases, the plant may develop symptoms several years later after the initial infection.



What can you do for veticillium wilt? Avoid root and collar injury. Keep your magnolia vigorous. Trees and shrubs killed by Verticillium wilt should be removed with as much of the roots intact as possible. Plants showing early symptoms should be watered and fertilized. Use fertilizers lower in nitrogen and higher in potassium. Sterilize tools between pruning and removal of infected plants and pruning healthy plants. Allow several years (three or more) before growing a susceptible plant in an infected area. Do not plant back into the same hole! There are no proven cures (chemical or cultural) for this disease.