Palm trees are some of the most versatile and disease-resistant trees, but even they have weak areas--the root system of the palm tree is one. Most grow in sandy, aerobic soils for a reason. If the conditions are not exactly right, then there can be a big problem with the roots, which can be attacked by a number of fungi promoting rot.
One of the first signs of root rot is a wilting of the spear leaves, the new leaves that grow from the center and remained unopened. Discoloration will also take place on older leaves, eventually turning them from lighter green, to yellow and then to brown. As the disease continues to develop, there may eventually be an unpleasant odor, especially around the areas from where the leaves emerge.
Root rot can affect any palm tree, but there are some that are more susceptible than others, especially when it comes to the fungus known as phytophthora. This fungus attacks slower-growing species more than faster-growing ones. Further, if the soil retains a great deal of moisture, it leads to more problems.
With so many fungi causing root rot, the problem is finding the one responsible for the problem. A sample of the root, and possibly the soil, is usually needed to determine this precisely. Take the sample to a local agriculture lab or an extension office, which can forward the specimen on for testing. This will cost money but also help determine the most appropriate course of treatment.
One of the best ways to prevent palm root rot is simply to make sure you choose a well-drained location with sandy soil. If transplanting trees, be certain that you do not plant the trees too deep. Even a few inches can make a big difference because moisture tends to stay in the soil past the first few inches. Try to plant the tree in its new location at the same depth it was originally planted.
If you have a question about whether the tree may be able to survive, consult a specialist. One of the most effective treatments is fungicide. The exact ingredients are determined by the type of fungus attacking the tree, which is why diagnosis and testing are so important to the final treatment decision. In some cases, if the tree is not able to survive, cutting it down quickly to prevent a spread of the infection is recommended.