Proposal for a New Coconut Standard
Posted on Dec. 11, 2023 / Invasive Species, Nursery, Plant Pests, Arboriculture / Subscribe 0
By: Mark Fukui
La’au niu (Cocus nucifera), or coconut palm, has woven its way through Hawaiian and local culture with its many uses. From providing weaving materials to sustenance, it’s no wonder why this palm became such an iconic image of Hawaii. This image not only fills the daydreams of travelers but the minds of landscape architects.
La’au niu is commonly planted throughout hotels, commercial, and residential properties. It is typically specified in landscape plans to require brown trunk heights of eight to fifteen feet. Keep in mind that coconut palms, once established, grow an average of one foot of brown trunk per year. After taking into account an establishment period of two to three years, la’au niu will take roughly fifteen years to reach twelve feet brown trunk height.
Prior to the introduction of the coconut rhinoceros beetle (CRB) in Hawaii, growing time wasn’t a major consideration in the planting of coconuts. However, Oahu, and more specifically Waimanalo, became the newest front line for the battle against CRB. Keeping coconuts clean and free of CRB damage for fifteen years is a daunting task.
To produce a product free of CRB damage, la’au niu should be specified at six feet brown trunk height. While there are methods to prevent CRB spread and damage, it does not guarantee pristine coconuts. Preventing breeding sites can be done by paying to dispose of green waste to have it taken off-site for proper management. This is a costly measure and an uphill battle as the natural vegetation in Waimanalo already provides an excellent breeding site for CRB.
Sand and gill netting can be placed in the crowns of young la’au niu to trap and prevent burrowing damage from CRB. While the recommended gill net size is ½” inch, it is still illegal to purchase gill netting smaller than 1 1/2 inch stretched net on the island of Oahu (HAR 13-75, HAR 13-95). These measures have to be redone every quarter as new fronds become exposed, and it will become increasingly difficult as their crowns become out of ladder reach.
Tree injections, a costly treatment, can be done annually. This is the best solution for la’au niu with heights that can’t be easily reached with ladders. Please remember that CRB burrow with their legs and only start feeding from the palm once the center of the crown is reached. So, even with injections, CRB damage will still be present.
These treatments offer no guarantee, are time intensive, and costly. At the end of the day, it doesn’t matter how much effort or money is put in if a neighbor has an unattended mulch pile acting as a CRB breeding site. The expectations for la’au niu coming out of the nurseries need to change. It is much easier and practical to prevent CRB damage on la’au niu under six-foot brown trunk height, and the turnaround time of roughly nine years, instead of fifteen years, will expose the coconuts to much less risk in the nursery. As long as CRB is around, the days of pristine fifteen to twenty-foot clear brown trunk la’au niu might be over.
Figure 1. CRB damage on 25 gallon Martii.
Figure 2. Mark Fukui standing next to a six-foot brown trunk-height coconut.
Figure 3. CRB trapped in gill netting.
Figure 4. CRB damage in Fiji fan palm.
Mark Fukui, Owner and manager – Contemporary Landscaping LLC
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