Thursday, July 5, 2012

Five New Weed Risk Assessments by USDA APHIS PPQ

Five New Weed Risk Assessments by USDA APHIS PPQ

1) Araujia sericifera Brot. (Apocynaceae) – Cruel plant: The result of the WRA for A. sericifera is High Risk. A. sericifera is a woody evergreen vine that smothers native shrubs and trees (Weber, 2003), impacts citrus production (CDFA, 2011), and can kill native insect pollinators (EPPO, 2008; Weedbusters, 2011). Comparison of A. sericifera to the 204 species used in the validation of the WRA model indicates that it shares many of the same traits and impacts as other major-invaders and high-scoring minor-invaders. 

2) Neptunia oleracea Lour. (Fabaceae) – Water mimosa: The result of the WRA for N. oleracea is High Risk. N. oleracea is a floating aquatic plant that spreads quickly over the surface of fresh bodies of water and replaces native wetland plants, blocks water flow in creeks and drains, restricts boat access, and reduces water quality (Queensland Government, 2009). Comparison of N. oleracea to the 204 species used in the validation study indicates that it shares many of the same traits and impacts as other major- and high-scoring minor-invaders.

3) Nymphoides indica (L.) Kuntze (Menyanthaceae) – Water snowflake: The result of the assessment for N. indica is High Risk. N. indica is an aquatic plant that spreads by seed and vegetatively through underground roots. It has naturalized in Texas and Florida, and is considered to be spreading rapidly in Florida (Saunders, 2004; Jacono, 2002). Comparison of N. indica to the 204 species used in the WRA model validation study indicate that N. indica shares many of the same traits and impacts as other major- and high-scoring minor-invaders

4) Oplismenus hirtellus (L.) P. Beauv. subsp. undulatifolius (Ard.) U. Scholz (Poaceae) – Wavyleaf basketgrass: The result of the weed risk assessment for O. hirtellus subsp. undulatifolius is High Risk with a relatively low level of uncertainty (Figs. 2 and 3). This taxon forms dense mats, which replace native species, prevent regeneration of native hardwood tree species (Westbrooks and Imlay, 2009), and render areas undesirable for recreational use (Kyde, 2010). Efforts are underway to detect and eradicate this taxon from Maryland (Kyde and Marose, 2008) and Virginia (PEC, 2012). A taskforce was established in 2008 to focus on mapping and eradication of known infestations (Westbrooks and Imlay, 2009). They have developed a public awareness campaign to help detect and report infestations before they become widespread. Land managers believe that, if left unchecked, O. hirtellus subsp. undulatifolius will have a devastating impact on the deciduous forests of eastern North America for many decades (Westbrooks and Imlay, 2009). Plant managers, state and local native plant societies, Native American tribes, and others wrote an open letter to Congress requesting funding to combat O. hirtellus subsp. undulatifolius in Maryland and Virginia and prevent its spread into other states (Ford and Imlay, 2012).

5) Toona sinensis (A. Juss.) M. Roem. (Meliaceae) – Chinese toon/Chinese mahogany:
The result of theWRA for T. sinensis is Evaluate Further (Fig. 2; Fig. 3); the secondary screening gives a result of High Risk. This species has been in the United States for decades and only recently have people begun to report invasive behavior. Although it has characteristics in common with many invasive trees (rapid growth, vegetative reproduction), it has not been aggressive in its introduced range and does not appear to be comparable to the similar species Ailanthus altissima, for example. Based on the available evidence, T. sinensis is likely to be a minor invader (70.4 percent probability) in natural areas and a nuisance in gardens and landscape plantings, primarily because of its tendency to produce seedlings and root suckers up to 50 feet from the parent tree.

Click here to request the Weed-Initiated Pest Risk Assessment Guidelines for Qualitative Assessments