2025 Oʻahu Weed Control and Restoration Workshop

This workshop was brought to you by the Priority ONE (Oʻahu Native Ecosystems) Working Group. Members of the organizing team represented the Waiʻanae Mountains Watershed Partnership, DOFAW's Native Ecosystem Protection and Management, Kualoa Ranch, the Army Na…

Invited presenters gave updates about LFA on Oʻahu (OISC), coqui frog on Oʻahu (DOFAW and partners), biocontrol development for Natural Area weeds (USDA-FS), and an overview of the inaugural meeting of the Hawaiʻi Drone Hui. Breakout discussions centered on th…

Click through to watch each presentation or view the slides. Questions from the audience are recorded under each session — expand any question to see the answer given on the day.

Overview of Little Fire Ant status across the state and on Oʻahu, LFA biology, human–LFA interactions that facilitate invasion, and control strategies including monitoring, detection, and treatments.

Treatments every 6 weeks, for 12 months.

Toxicant (granular) on the ground, spray growth inhibitor (liquid) in trees.

Testing quarterly is sufficient. If you are LFA free you can even test annually.

Every 10 steps.

No.

Yes — reach out to OISC for language and SOPs that will ensure folks test for LFA, or have OISC check your existing language.

Plants and landscaping. Large landscaping projects can spread ants very quickly. Not all nurseries have LFA, but those with detections are working with HDOA. A nursery having no past detection does NOT mean it is LFA free — consistent testing is needed to be c…

Overview of the coqui frog invasion on Oʻahu, the history of control efforts, the Waimānalo community initiative, collaboration between OISC, DOFAW, HDOA and affected communities, and the application of innovative drone methodologies for survey and control wit…

With a long tube. Listen for the frog, position the tube opening in front of it and the frog will jump in. Tubes are getting harder to find as fluorescent lights are phased out. We also need plastic bottles to store caught frogs — give us your Gatorade bottles…

Status of biocontrol agents under development for Natural Area weeds.

An overview of the inaugural Hawaiʻi Drone Hui meeting.

Regulations that limit flights to line of sight; interaction with piloted aviation; operating at night — automated flights have proven a good workaround, and if you can fly in daytime you can fly at night; some targets are easier than others, with low-to-the-g…

Additional questions?

Two posters shown at the workshop are not yet in this gallery: ANRPO direct seeding (field germination) and the KMWP seed ball poster. They will be added once files are received.

This section synthesises the CRB information shared across programs. The programs represent a mix of environments spanning developed and natural areas, and manage a mix of native ecosystem restoration sites, native palm populations, or non-native palm collecti…

Not too many other preferred species (banana, hala, etc.) are available at the gardens, but we might explore control methods on kalo next. There are a lot of collections in the gardens.

Merit is a granular product, but probably not a long-term solution. Drenching takes too long and is not feasible. Crown injection also consumes staff time. There is money to fund a full-time team of two for four months performing crown injections on coconut.

No rares have come back, but one at Hoʻomaluhia regrew after being eaten by CRB.

These are often lowest priority for removal at the gardens and could take 4–5 months. It may be worth landowners doing it themselves by netting the trunk, with the goal of the slowest decay. Cutting and chipping might get everything already in the pile but wou…

CRB tend to fly high and mostly hit taller trees. At first the decision was to halt planting more loulu at the gardens, but that will be reconsidered. Decoy trees might be a good distraction.

No — we usually find them while outplanting, and through moving soil around we find grubs.

Yellow crazy ants are possibly preying on CRB, though it is unclear whether they are deliberately going after them or finding them as food after the fact.

Yes. Deteriorating netting creates large piles of nets with holes and eventually microplastics. There are two types on the market to consider: polypropylene and high density polyethylene.

Only pheromone traps are in use in Mākaha, and more are found all the time. The Army Natural Resources Program has set up breeding site traps, but nothing has been caught in them yet.

HDOA is currently making guidelines on how to manage CRB and guiding requirements for laws. One suggestion was that they also include verbiage on proper disposal of netting materials.

A working summary table drawn from the nursery germination posters and discussion. This is a living resource — if you have similar or differing germination experiences, or other species you want to improve rates for, let us know. During the discussion the grou…

These species have information gaps in the Weed Control Matrix, and/or were indicated as species of interest through the pre-workshop survey. Each group worked through a worksheet structured around the key steps to setting up an herbicide trial. Two different…

Identify the problem — species, management challenge, management goal. Research — review existing literature, use existing resources such as the Weed Control Matrix, ask around, and gather takeaways. Describe the plant — monocot or dicot, herbaceous or woody,…

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