2010 ASHS Invasive Plant Workshop

The Role of Horticulture in Managing Plant Invasiveness and Reducing New Invasive Introductions in the U.S.

Amer. Soc. Hort. Sci. Ann. Conf.  HortScience 45: 28-29.
: Nursery (NUR) Working Group)
: Jyotsna Sharma and Jim Owen

Objective: 1. To facilitate a discussion and exchange of ideas on the role of horticulture in plant invasiveness in the U.S. via structured presentations followed by a panel discussion. 2. To discuss in detail: (1) a history of plant invasiveness in the U.S., (2) terminology associated with invasive plants, (3) breeding methods to reduce the invasive potential of nursery crops, and (4) current approaches for managing invasive plant populations. 3. To engage in an open discussion with the panelists including invasive plant researchers and specialists from academia, government, and industry.

The plant and nursery industries in the U.S. are intricately involved in all aspects related to introduction, management, and handling the consequences of plants that have become invasive or may have the potential to become invasive. With plant invasiveness rapidly becoming an economic and ecological personnel on the latest information on science and technology for preventing, managing, or reducing invasive plants. Our workshop is designed to bring together researchers, specialists,  regulators, and stakeholders to discuss the role of plant industries in managing invasive plants in the U.S.

Invasive Plant Terminology

James Altland
USDA-ARS, Wooster, OH

The nursery and landscape industries are often viewed as major pathways for introduction of invasive plants. Whether this recognition is deserved or not, states and government entities are passing restrictive legislation. The horticultural industry should be proactive in dealing with invasive plant issues before legislation forces them into undesirable programs or practices. One of the problems facing the horticulture industry is the lack of a consistent and accurate terminology to describe invasive plants. Ecologists have been debating invasive terminology for many years. They still do not agree precisely what constitutes a native plant, much less what constitutes an invasive plant. In the interest of promoting uniformity of language in the business of nursery crop production, the following terminology is recommended for the United States. Use the term native to describe plants that naturally occurred in a particular habitat or region prior to Euro-American settlement. Use the term non-indigenous species (NIS) to describe plants that are not native. Avoid using the term alien, as this and similar terms have been viewed as racist. Use the term invasive to describe populations of plants that produce reproductive offspring, often in very large numbers, and distribute those offspring at considerable distances from parentplants and thus have the potential to spread over a considerable area and cause economic or environmental impact. Avoid using the term noxious. Noxious is not an ecological description, but a label applied by government and other entities whose criteria vary greatly.

See video of Dr. Altand's presentation at HortTalks provided by the Amer. Soc. Hort. Sci.


History of Plant Invasiveness

Richard T. Olsen
U.S. National Arboretum, Washington, DC

Weed species, invasive or otherwise, have advanced lock-step with the rise of agriculture and the advancement of human cultures. In North America, the introduction of exotic species began with the first colonists and continued unabated with the rise in global trade. So what changed late in the 20th century to explain the meteoric rise in the science of biological invasions? Have scientific advancements in ecology shown us a new path? Have urban sprawl and habitat fragmentation left a void to be filled by an opportunistic cultivated flora? Has there been a significant evolution in values that competes with objective science and politicizes invasive species, turning the very act of cultivating plants into a series of moral judgments? Plants originally cultivated for ornament are prime targets, as they are often viewed as having the least value but the highest risk in invasive risk cost-benefit scenarios.

See video of Dr. Olsen's presentation at HortTalks provided by the Amer. Soc. Hort. Sci.


Breeding Methods to Reduce the Invasive Potential of Nursery Crops

Ryan Contreras
Oregon State University, Corvallis, OR

Legislation to restrict production and sale of economically important nursery crops considered invasive is being proposed and enacted in numerous states. The estimated value of nursery crops considered invasive is in the hundreds of millions. In addition to the economic impact, these plants often fill a niche in the urban landscape by growing well under strong abiotic pressure and exhibit resistance/tolerance to pests and diseases that native species have difficulty withstanding. As a result, it is important to develop forms that have reduced fecundity, which will allow growers to market forms of these hardy, non-native species without the danger of causing economic or environmental harm. Techniques to develop forms with reduced fertility such as ploidy manipulation, interspecific hybridization, mutagenesis, and combinations of thereof will be discussed.

See video of Dr. Contreras's presentation at HortTalks provided by the Amer. Soc. Hort. Sci.


Current Approaches for Managing Invasive Plant Populations

Robert Leavitt*

California Department of Food and Agriculture, Sacramento, CA

The California Department of Food and Agriculture (CDFA) is charged with identifying, preventing, eradicating and/controlling invasive plants, also known as noxious weeds. This includes preventing their entry into the state at the border protection stations.

It also includes preventing the artificial spread of noxious weeds in horticultural crops by regulation. The CDFA works with county agricultural commissioners, cooperative weed management areas, and other agencies and partners to control and eradicate noxious weeds. The CDFA is an active member of the California Horticultural Invasive Prevention partnership and the works with PlantRight campaign to encourage the voluntary removal of noxious weeds from horticultural production.

See video of Dr. Leavitt's presentation at HortTalks provided by the Amer. Soc. Hort. Sci.