It’s been seven years since the industry was first introduced to the University of Hawaii Weed Risk Assessment, a tool for predicting the potential invasiveness of plants. In the beginning, the green industry struggled with the weed risk assessment, but a lot has changed since 2004.
In 2006, the landscape industry started an initiative to determine which potentially invasive plants have greater risk than benefit. The initiative included broad outreach with numerous meetings on all islands including the Hawaii Island Landscape Association, Kauai Landscape Industry Council, Maui Association of Landscape Professionals, Oahu Nursery Growers Association, The Outdoor Circle, Hawaii Society of Urban Forestry, Aloha Arborist Association, Hawaii Landscape & Irrigation Contractors and the American Society of Landscape Architects.
After three years of meetings and lengthy discussion, the industry came together and agreed that of the 168 plants listed as potentially invasive, that 80% would not be utilized. The Landscape Industry Council of Hawaii Invasive Species Guidelines and Invasive Plant List became on effective May 1, 2009. The list and the guidelines are online at www.landscapehawaii.org.
It’s now been two years and I am sure many folks are wondering just how successful is the implementation. Are we walking the talk and what’s the next steps? Well some preliminary statistics are now available on a handful of landscape nurseries from the Islands of Oahu and Maui. We do not currently have statistics for Kauai or the Big Island. This statistics exclude national big box stores that typically do not participate in our local industry.
On the Island of Maui, botanists found 11 of 134 LICH invasive plants or 8% being propagated and sold at local landscape nurseries. The 11 LICH invasive plants include: Asparagus steaks, Clerodendrum quadriloculare, Cyperus involucratus, Hedychium gardnerianum, Psidium guava, Salvinia molesta, Schefflera actinophylla, Schinus molle, Tecoma stans, Thunbergia grandiflora, and Tillandsia unsteadies.
On the Island of Oahu, botanists found 18 of the 134 LICH invasive plants or 13% being propagated and sold at local landscape nurseries. The 18 LICH invasive plants include: Adenanthera pavonina, Alocasia cumulate, Asystasia gangetica, Buddleja David, Chrysophyllum oliviforme, Clerodendrum buchananii, Clerodendrum quadriloculare, Cyathea cooperi, Cyperus involucratus, Gazania rigens var. Leucolaena, Lantana camara, Phormium tenax, Pithecellobium dulce, Schinus molle, Solanum seaforthianum, Tecoma stans, Tibouchina urvilleana and Turnera ulmifolia.
So what does 8% on Maui and 13% on Oahu mean? Are we doing well or are we in trouble? Zero invasive plants is the goal but we are making progress. Many more landscape professionals are aware of the choices available and considering whether we really need this plant versus using a non-invasive plant. In the next year, the Landscape Industry Council of Hawaii will explore developing best management practices associated with the industry list.
As an industry, we agreed that all of these plants should not be propagated or sold through an exhaustive and inclusive 3 year effort. I would encourage every landscape professional to take a moment from your busy schedule and review the LICH invasive plant list and guidelines and double check that your office is not propagating, selling, or specifying these plants. As an industry, Hawaii has accomplished what no other state has in taking a proactive stance on self regulating the use of the invasive plants, but we must continue to be vigilant and continue leading by example.
Chris Dacus is a Landscape Architect and Arborist for the State of Hawaii Department of Transportation and the president of LICH.