Invasive-weed infestations within Maui County are literally a growing problem. Despite the tough economic recession, invasive species prevention and mitigation programs remain a necessity for conserving our natural and agricultural resources. We need to look back only a few months ago to remember the show of local support for our Hawaii Department of Agriculture inspectors. While some positions were retained, Maui still must deal with the losses of important HDOA positions. Despite these setbacks, our local ranchers and natural area managers remain steadfast to continue the fight against these detrimental weed infestations, simply out of necessity.
In support of these efforts, the University of Hawaii’s College of Tropical Agriculture and Human Resources, or CTAHR, is providing a new service in research and extension to the county and across the state. Being new to this position, I currently spend much of my time gaining more intimate knowledge of the invasive-weed problems across Maui so we can develop a research and extension program that will provide new technologies for the "boots on the ground" on our island. My current mission is to investigate efficient management strategies that are environmentally sound and cost effective. Below I describe some of the ongoing work currently being conducted.
Mowing is a tool that has been utilized for decades, but often is relegated to roadside and residential areas for maintenance and beautification. It rarely has utilities as a dedicated method in weed management. Too many times, we’ve observed weeds respond to mowing with aggressive regrowth, thus making the situation a perpetual battle. In a collaboration between CTAHR and American Machinery Inc., field studies are testing the Wet Blade technology of Diamond Mowers Inc. The technology integrates mechanical mowing with an herbicide wiper application. So far it’s proving to be quite useful in eradicating some of the worst weed infestations from our grazing pastures.
The Wet Blade currently in use for on-island demonstrations is a 6-foot-diameter rotary design with swivel-mounted blades made of thick, hardened steel coated with a thin herbicide layer on the underside of the blade. As the mower blade is cutting the vegetation, the herbicide residue is applied instantly to the freshly cut weeds without any drift or nontarget injury. Early results for this technology are proving successful on guava (Psidium guavaja), rauvolfia (Rauvolfia vomitoria), Sacramento burr (Triumfetta semitriloba) and the dreaded fireweed (Senecio madagascariensis). Currently, this technology is showing to be most useful in small-scale pasture renovation, conservation site clearing, orchard-row maintenance and even firebreak establishment.
An important component of all invasive-weed management strategies is to mitigate efficiently and effectively the spread of small satellite populations to prevent them from becoming major infestations. Many natural areas in Hawaii consist of extremely steep, densely vegetated or otherwise inaccessible terrain that requires a significant amount of time and energy to access for eradication. Accessing certain areas requires rappelling, which is dangerous but necessary work. CTAHR is developing new technologies that can deliver discreet herbicide doses accurately from safer long-range distances.
The recreational paint-ball industry has contributed to the technological advancements of liquid encapsulation and pneumatic ballistics. These existing technologies have been adopted for developing a new invasive-weed-management tool called Herbicide Ballistic Technology, or HBT. Small volumes of herbicide are encapsulated into gelatin projectiles that can be delivered to specific weeds with extreme accuracy using a standard paint-ball gun. The first prototype batches of HBT capsules were highly effective in trials targeting Australian tree fern (Sphaeropteris cooperi), banana poka (Passiflora mollissima) and kahili ginger (Hedychium gardnerianum) from more than 100 feet away. While HBT is still in the stage of experimental development, we have high hopes that this new technology will become available for assisting field crews with safer pesticide handling and an improved application technique that ultimately will provide a more surgical approach to weed control.
To learn more about the technologies being developed for invasive-weed management in Hawaii, please visit our "HawaiiRREA" channel at www.youtube.com, and for further inquiry, please contact your new extension specialist at leary@hawaii.edu. The use of brand names in this article are not endorsing these products so much as promoting the concept of adopting new technologies for safe and effective weed management.
* James Leary is a specialist for the invasive-weed-management station at the Maui Agricultural Research Center in Kula.He holds a doctorate in weed ecology from the University of Hawaii at Manoa. Kia’i Moku, Guarding the Island, is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.
