Fusarium oxysporum is a fungus that attacks primarily Canary Island date palms. There is no cure, and fungicides are not effective. The disease symptoms normally appear first on the oldest, or lowest fronds first, and move upward in the canopy until the palm is killed. Symptoms include a one-sided die-back of fronds, where the leaflets on only one side of the rachis turn brown before the entire frond turns brown and dies. This disease is caused by contaminated chain saws or pruning tools. This disease is well established and is not going away. You may notice that The Irvine Company and other large developers are using Phoenix dactylifera whenever possible instead of Phoenix canariensis .
Usually 6-18 months. No visible symptoms during this time. Once visible symptoms appear, tree can take months to 5 or more years to enter the "rapid-decline" stage and die.
According to Mark Robinson of MTR Horticulture in La Costa, 760-804-0729, the leading authority in the state on Phoenix canariensis palms, these are some key points to be aware of:
Prevention is key. Never prune your Phoenix palm with a chain saw. Use a sterile hand saw to prune. Clean tools in a 50/50% solution of bleach and water for a minimum of 20 minutes. Clean tools before and after each tree. Make sure your palm problem is properly diagnosed, and the problem is not a nutrient deficiency or another disease. Problems occur from improper planting, deep planting, improper irrigation practices, and poor nutrition. Always purchase Phoenix canariensis palms only from reliable resources. Have a Horticulturist that specializes in palms inspect your palms before delivery.