Experts Battling to Save Coconut Palms in Hawaii pg.2
Huelo Point on Maui has suffered some of the most
devastating losses.
In the ensuing months, more leaves die and fall, leaving a few lower fronds. Roots and lower trunk tissue remain healthy and functional for many months and continue to supply the lower leaves with nutrients and moisture.
Eventually all of the fronds drop, producing leafless trunks. Less frequently, older leaves die first, resulting in palms with only a few young, upright fronds. Because young leaves are vertically oriented, infected plants appear rigid. By the time leaf death is observed, internal rot is already at an advanced stage. These diseased palms have large rotted areas that involve most of the terminal bud.
Killing of the single growing tip ultimately causes the death of the palm. Diseased nuts and heart rots, followed by plant death, have been associated with a Phytophthora species. The pathogen of coconut produces abundant and distinctive sexual spores in host tissue. Each spore is produced in a mother cell that has distinctive blister-like swellings and a long base.
How to combat the pathogen
Once palms are infected, death from the disease appears to be inevitable, and several hundred have been lost throughout Hawaii since 1970. Because the host range of Phytophthora appears to be confined to coconut, eradication and exclusion are feasible control options. All infected palms and nuts should be destroyed by incineration or deep burial.
Prompt removal of diseased palms will reduce the probability of soil contamination with the pathogen. The sexual spores of most Phytophthora species are able to survive in soil without the host plant. Removal of diseased material will also prevent spread of the pathogen to healthy ones.
