Injections:

Injecting host plants with Imidacloprid and Acephate have shown promising results in reducing CRB populations when applied to most palms in the area. Treating a minority of palms in a neighborhood or region is unlikely to provide satisfactory protection because beetle populations will thrive from feeding on untreated trees nearby. These treatments are ideal for high-density plantings where access to the crown is not available because most formulations have no acreage limitations, minimal off-target impacts (no soil leaching or off spray, and treatments are applied near ground level. However, the process is slow, labor-intensive, and sometimes requires expensive equipment. Imidacloprid is predominantly used for injections because research at UH indicated that CRB were sensitive to this chemical. There are multiple products that contain this active ingredient but CRB Response has been using Imajet (annual reapplication) and AceJet (6-months reapplication). Systemic injections require trimming of flowers every six months to protect pollinators and fruit can not be consumed until after the pre-harvest interval or reapplication interval.

Soil drench:

Imidacloprid drenches, like Merit 75 WSP, can be applied as a soil drench for systemic treatment of palms, though its field efficacy in this method hasn't been tested. Fully trimmed palms can be treated as "shrubs" per label instructions. This method is quick with low startup costs but has per-acre limits (~96 vertical feet of palms per acre) and cannot be used near bodies of water due to leaching risks. CRB Response has only used Imidacloprid for soil drenching primarily for young palms that are too small for injections. Soil drench requires trimming of flowers and fruits every six months to protect pollinators and fruit can not be consumed until after the pre-harvest interval or reapplication interval. 

Crown Application:

Spraying the crown with pyrethrins or pyrethroids like cypermethrin and cyhalothrin   effectively kills CRB in both lab and field settings. Some pesticides are labeled as “restricted use” and require application by certified applicators. Some have region specific application restrictions so check the label and consult with an extension agent or pesticide specialist if you are unsure. The chemical should be applied only to the base of fronds where they meet the heart of the palm near the spear and upper central crown area. Applications can also be made directly into CRB boreholes.  Application to frond leaflets, emerged foliage, fruits, or flowers will have little effect on CRB and may increase off-target effects. Various application methods have been successful, including drone application, backpack sprayers, and ground pump application. Access to the crown for targeted application to tall palms may require a lift, ladder, or spray wand. We do not recommend spraying pesticide from below the crown due to concerns for safety and precise application.

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Pyrethrins (natural plant extracts) and pyrethroids (synthetic versions) both paralyze and kill CRB on contact. They provide rapid effects but relatively short-term residual activity as they degrade in sunlight. Apply to plants with recent CRB damage or suspected active feeding.

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Evergreen Pyrethrum Concentrate and OneGuard are products that have been used by the County of Oahu and UH that have fewer label requirements and may be easier for home use. MustangMaxx is a restricted use product that requires a State-certified applicator license but may be used on coconuts grown for fruit production, while DemonMaxx is temporarily allowed for coconut crowns through an emergency exemption on all islands except Oahu with prior notification and approval from HDOA pesticides division.