Exotic Pest Plant Council Research Articles

Napiergrass: Biology and Control in Sugarcane

Napiergrass (Pennisetum purpureum Schumacher) is an enormous, weedy, cane-like grass (Figure 1) commonly seen growing along canals and roadsides in the sugarcane production area of south Florida. Napiergrass, also known as elephantgrass, has been documented in almost 30 counties throughout Florida. It is of African origin, but has been introduced to all tropical areas of the world because of its ability to quickly produce large amounts of biomass. Currently, napiergrass is widely used in Central America, South America, and Africa as a forage crop. Napiergrass was introduced to South Florida and Texas for use as a forage crop, but it is no longer widely used for this purpose and has become a major weed problem. Napiergrass is now established throughout southern Florida, especially along canal and ditch banks and in disturbed or cultivated areas. Because of the weedy characteristics of napiergrass, it is considered to be one of the world's worst weeds and has been listed as an invasive species by the Florida Exotic Pest Plant Council. Although it can be found in central and northern Florida, it is less common due to cooler temperatures. This document is SS-AGR-242, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date: July 2005. Reviewed October 2008. 
 SS-AGR-242/SC071: Napiergrass: Biology and Control in Sugarcane (ufl.edu)

Evaluation of Control of Napiergrass (Pennisetum purpureum) with Tillage and Herbicides

AbstractNapiergrass has potential as a cellulosic biofuel crop because of its rapid growth habit in the southern United States. However, it is also listed as a potential invasive species by the Florida Exotic Pest Plant Council. For field renovation, information about napiergrass control in response to tillage and herbicides is required. Field studies were initiated to evaluate control of napiergrass established in fields for over 3 yr at Plains, GA, and Tifton, GA. For tillage and POST herbicides, imazapyr plus glyphosate consistently controlled napiergrass relative to diclosulam plus glyphosate, sulfentrazone plus glyphosate, or tillage in terms of visual injury, stem height and dry biomass reduction. One application of imazapyr plus glyphosate controlled napiergrass 74 and 94%, and reduced plant stem height to 6 and 15% of the nontreated control. When diclosulam plus glyphosate, sulfentrazone plus glyphosate, or tillage was used alone with no sequential herbicides, napiergrass control ranged from 12 to 33%; when these control tactics were followed by two sequential applications of either sethoxydim or glyphosate, napiergrass control varied from 45 to 99%. Reductions in plant heights were reflective of injury 47 d after final herbicide applications (May/June). Napiergrass yield in dry biomass production was reduced by imazapyr plus glyphosate ≥ 86% relative to the nontreated control (NTC). Diclosulam plus glyphosate, sulfentrazone plus glyphosate, or tillage alone was not effective in reducing napiergrass dry biomass yields ranging from 1 to 47% compared with the NTC; when these treatments were followed by sequential applications of sethoxydim or glyphosate, napiergrass dry biomass was reduced 46 to 91% compared with the NTC. Tillage plus two applications of sethoxydim or glyphosate exhibited control potential because they provided levels of napiergrass control similar to imazapyr-based treatments. Tillage plus multiple applications of sethoxydim or glyphosate offers flexibility to crop rotations as compared with the residual herbicide imazapyr, which has many crop rotation restrictions because of carryover concerns.

Managing Mexican Petunia (Ruellia simplex C. Wright) in the Home Landscape

Environmental tolerance, abundant seed production, and an ability to easily grow from plant stem sections have allowed Mexican petunia to spread into natural areas that border urban areas. The Florida Exotic Pest Plant Council lists Mexican petunia (wild-type and non-sterile cultivars) as a Category 1 invasive species, meaning that it is “altering native plant communities by displacing native species, changing community structures or ecological functions, or hybridizing with natives.” These potential changes to community structure and ecological function are of particular concern in Florida wetlands, where changes to plant communities have the potential to impact not just plant-animal interactions, but also overall hydrology on a whole watershed level. This 6-page fact sheet was written by C. A. Reinhardt Adams, C. Wiese, L.C. Lee, S.B. Wilson, A. M. Smith, and R. Freyre, and published by the UF Department of Environmental Horticulture, April 2014.

Natural Area Weeds: Old World Climbing Fern (Lygodium microphyllum)

Native to Africa, Asia, and Australia, Old World climbing fern (OWCF) is a newcomer to Florida that has spread at an alarming rate since its introduction. The Florida Exotic Pest Plant Council considers Old World climbing fern to be invasive. It’s also regulated by laws of the Florida Department of Agriculture and Consumer Services (FDACS) as a Florida Noxious Weed and by the United States Department of Agriculture (USDA) as a Federal Noxious Weed. It may be the most serious threat to Florida’s natural areas. This 6-page fact sheet was written by Kenneth A. Langeland and Jeffery Hutchinson, and published by the UF Department of Agronomy, February 2013.
 http://edis.ifas.ufl.edu/ag122

Natural Area Weeds: Skunkvine (Paederia foetida)

Native to eastern and southern Asia, skunkvine is an invasive plant species introduced to the USDA Field Station near Brooksville before 1897. It has been included on the Florida Exotic Pest Plant Council List of Invasive Species as a Category I, defined as “species that are invading and disrupting native plant communities in Florida.” It was added to the Florida Noxious Weed List in 1999, making it illegal to possess, move, or release in Florida. This 3-page fact sheet was written by K. A. Langeland, R. K. Stocker, and D. M. Brazis, and published by the UF Department of Agronomy, February 2013. 
 http://edis.ifas.ufl.edu/wg208

CHARACTERIZING THE INVASIVE POTENTIAL OF ORNAMENTAL PLANTS

The substantial economic and ecological costs of invasive plant management and removal warrant aggressive eradication and prevention programs. Ornamental horticulture has been recognized as the fastest growing segment of U.S. Agriculture, as well as the main source of plant invasions worldwide. Florida ranks second among U.S. states in the degree of ecosystem devastation as a result of exotic invasive species. Cultivated or improved forms of a number of the ornamental species listed as invasive by Florida’s Exotic Pest Plant Council have been selected for their attractive flower color, plant form, foliage, drought tolerance, or cold hardiness. As the cultivars are generally propagated vegetatively, relatively little is known about their pollination biology, seed production, seed viability and growth rate under varying conditions. To identify safe alternatives to ornamental invasives, researchers at the University of Florida have evaluated numerous cultivars of Mexican petunia (Ruellia tweediana), privet (Ligustrum spp.), fountain grass (Pennisetum spp.), porterweed (Stachytarpheta spp.), heavenly bamboo (Nandina domestica), and lantana (Lantana camara). These species are not only problematic in Florida, but highly invasive in other parts of the world. Research efforts are underway to identify and evaluate sterile non-invasive forms of lantana, heavenly bamboo, and Mexican petunia.

Exotic Plant Species of Cumberland Island, Georgia1

Abstract A survey of exotic plant species on Cumberland Island (Georgia) was conducted during 2003–2004. Of sixty-six exotic plant species identified, twenty-three of these are recognized as invasive or potentially invasive by either the Georgia Exotic Pest Plant Council (GAEPPC) or the Florida Exotic Plant Pest Council (FLEPPC) and 11 species occurred in natural areas of Cumberland Island National Seashore. Areas containing exotic plant species, obtained in the form of Geographic Information System layers, ranged from 1 m2 to 2,273,708 m2. Rankings of impact determined by the Alien Plant Ranking System (APRS) ranged from 4 to 60, but did not coincide well with rankings by the GAEPPC or FLEPPC. Five species listed by GAEPPC or FLEPPC ranked 40 or above by APRS, while all others ranked below 38.

Southeast Exotic Pest Plant Council (SE-EPPC): a Regional Approach to Invasive Exotic Pest Plant Issues

The Southeast Exotic Pest Plant Council (SE-EPPC) is a 650 member non-profit organization located in the southeastern United States. It emerged as a regional organization through efforts initiated by the Tennessee Exotic Pest Plant Council in the late 1990s. Its eight state chapters are autonomous organizations under the umbrella of SE-EPPC. The organization's focus is on issues of regional importance, and it has developed a web-based regional data-mapping project to improve early detection and rapid response, to provide data for regional invasive plant assessments, and to provide data to improve state invasive plant lists. SE-EPPC has been active in fostering the growth of other Exotic Pest Plant Councils (EPPCs) throughout the eastern United States and has fostered the growth of the National Association of EPPC, which has formed a partnership with the Natural Areas Association to work together on all issues related to invasive exotic pest plants in natural areas.

Implementation of Control and Prevention Strategies for Managing Cogongrass (Imperata cylindrica) by the Georgia Invasive Species Task Force

Abstract With only 49 known infestations, cogongrass, Imperata cylindrica (L.) Beauv., is an emerging invasive species in Georgia. To facilitate cooperation in all areas of management, both of cogongrass and other invasive species, state and federal agencies, university personnel, and Georgia Exotic Pest Plant Council members have combined to form the Georgia Invasive Species Task Force. The task force has adopted a four-fold approach to managing cogongrass in Georgia: (1) management of known infestations, (2) discovery of any existing but unknown infestations, (3) reduction of pathways of spread, and (4) preparation for new infestations. United States Department of Agriculture, Animal and Plant Health Inspection Service - Plant Protection and Quarantine, or Georgia Forestry Commission personnel are currently administering control efforts on known infestations. University of Georgia faculty and staff are maintaining a database of known infestations and have created an online mapping program of their locat...

New Records of Invasive Exotic Plant Species in St. Lucie County, Florida

Abstract Eighteen category one invasive species as defined by the Florida Exotic Pest Plant Council and nine category two invasive species are newly recorded for St. Lucie County, Florida as the result of surveys done by the authors from August through November 2003. These records document the rapid spread and need for increased monitoring of invasive species and the documentation of these specimens through the collection of herbarium voucher specimens. These records also highlight the gaps present in specimen vouchers in areas such as St. Lucie County due to a lack of monitoring.

The total number of naturalized species can be a reliable predictor of the number of alien pest species

In her recent paper, Shawna J. Dark (2004) concluded that the distributions of ‘invasive alien plants’ and ‘non-invasive alien plants’ in California were significantly correlated. She found the highest numbers of both ‘invasive’ and ‘non-invasive’ species in regions with low elevation, high road density, and high native species richness. Dark actually uses two definitions of ‘invasive’ in the paper; we discuss the implications of this on her conclusions. We point out that the most important message of Dark’s paper is that the total number of naturalized species can be, at least at some spatial scales, a reliable predictor of the numbers of exotic pest species. We also provide another example to support this conclusion. We follow the definitions of native, non-native, naturalized, casual, pest, and weed in Pysek et al . (2004) in this note unless otherwise specified. It is necessary to examine how Dark defined ‘invasive’ in her paper because the data she used include only a small number of plant species (78) classified as ‘invasive’ while the remaining 1097 naturalized species listed in the most recent statewide flora and online updates (total 1175; Hickman, 1993; http:// ucjeps.berkeley.edu/interchange.html) were classified as ‘non-invasive alien plants’. Dark first defines ‘invasive alien plants’ in the paper’s second sentence as ‘alien plants that produce offspring in very large numbers and at large distances from parent plants and thus have potential to spread over a considerable area (Richardson et al ., 2000)’. Later, however, we learn that species actually classified as ‘invasive’ for data analysis in this study are only those rated as ‘A’ and ‘B’ on the California Exotic Pest Plant Council’s (1999) list of ‘Exotic Pest Plants of Greatest Ecological Concern’ (Dark, 2004; text under Fig. 1; CalEPPC, 1999). CalEPPC (1999) in turn defines its A and B categories as covering species that

Florida Nursery Sales and Economic Impacts of 14 Potentially Invasive Landscape Plant Species

Abstract The Florida Nurserymen and Growers Association (FNGA) and the Florida Exotic Pest Plant Council (FLEPPC) recently asked nurserymen to stop production of 45 potentially invasive plant species that are relatively insignificant in the ornamental horticulture market. Controversies surround 14 additional species designated as invasive by the FLEPPC, but which are highly ornamental, widely used in landscaping, or have high economic value according to the FNGA. A mail survey of Florida ornamental nursery growers identified sales volume and value for each of these species. Economic output and employment impacts were calculated to determine the effect phasing-out these species may have on Florida's nursery industry. Total statewide sales of the 14 species were estimated at $45 million in 2001, with $34 million in-state and $11 million out-of-state. These sales translate into combined economic output impacts of $59 million and employment impacts of 800 jobs for Florida's economy, accounting for about 3% of total statewide output and employment impacts created by the ornamental nursery industry. These estimated impacts should not be interpreted as the expected industry loss from a phase-out of these species. If a species is not available for purchase, consumers will probably substitute alternative species, reducing the effect of any phase-out.

Seed Production and Germination of Eight Cultivars and the Wild Type of Ruellia tweediana: A Potentially Invasive Ornamental

Abstract Seed production and the influence of light and temperature on germination were determined for eight cultivars and the wild type form of Mexican petunia (Ruellia tweediana Griseb). The wild type form of R. tweediana has been ranked by the Florida Exotic Pest Plant Council as a Category I invasive plant, meaning it has invaded and is disrupting native plant communities in Florida. The cultivar ‘Purple Showers’ did not set any seed. Peak flowering and seed production for other cultivars generally occurred in August with ‘Morado Chi’, ‘Chi Chi’, and the wild type plants producing approximately three times the amount of seed produced by ‘Katie Pink’, ‘Katie Purple’, ‘Katie White’, and ‘Snow White’. For seed germination, significant cultivar x light interactions occurred for each temperature treatment. Some germination was observed at each temperature except for ‘Katie Purple’, ‘Katie Variegated’, and ‘Katie White’ at 33C (91.4F) without light. Regardless of cultivar or provision of light, 94-100% germination occurred at 30/20C (86/68F), with the exception of ‘Katie Purple’ (65%), ‘Katie Variegated’ (54%), and ‘Katie White’ (83%) without light. At 15, 24 or 33C (59, 75.2, and 91.4F), germination was generally greatest for ‘Chi Chi’ (with or without light) and ‘Morado Chi’ (with light). In parallel greenhouse studies, where seeds were germinated in pots containing a soilless medium, highest germination was achieved by ‘Chi Chi’, ‘Katie Pink’, ‘Katie Variegated’ and ‘Morado Chi’, while significantly lower germination was achieved by wild type plants (55%) by day 14. Storage studies demonstrated that germination of seed collected from the wild type and ‘Chi Chi’ plants began to decrease between 6 and 12 months when maintained at 24C (75.2F) but had equal (‘Chi Chi’) or higher (wild type) germination when maintained at 4C (39.2F) for 12 months.

BOOK REVIEWS: Invasive Plants of California's Wildlands

Abstract Invasive Plants of California's Wildlands provides detailed information on the biology and control of 78 nonnative plant species that were listed as Exotic Invasive Plants of Greatest Ecological Concern by the California Exotic Pest Plant Council. These invasive, nonnative species were discussed because they are already growing wild in California and are causing or have the potential to be a serious threat to state parks, preserves, and other wildlands.

Pathogenicity Assessment of Puccinia lygodii, a Potential Biological Control Agent of Lygodium japonicum in Southeastern United States.

Lygodium japonicum (Thunb.) Swartz (Family, Schizaeaceae) is naturally distributed from Asia to Australia and has naturalized in the United States from Texas to the Carolinas and Florida (4). Recently, it has been declared a Category I weed (the most invasive group) by the Florida Exotic Pest Plant Council. A foliar rust fungus was observed on a population of L. japonicum growing under the canopy of a pine/hardwood forest in Gainesville, FL. The lower surfaces of almost all the pinnules (foliage) were covered with cinnamon-brown eruptive pustules. Necrotic areas developed around mature, erupted, and coalesced pustules. Severely infected foliage were wilted and dried. Microscopic observations of the pustules and spore morphology revealed these eruptive structures to be uredinia. The dimensions (24.6 [+ 2.2] × 29.7 [+ 3.5] μm) and morphology (ellipsoid or obovoid, pale cinnamon-brown, and echinulate with indistinct pores) of urediniospore were similar to those reported for Puccinia lygodii (Har.) Arth. (Uredinales) (1). Therefore, the rust was identified as P. lygodii and confirmed by J. Hennen. P. lygodii is native to South America, where it has been recorded from L. volubile and L. venustum (2). This rust was previously identified as Milesia and Uredinopsis spp. on L. japonicum from Louisiana and Florida, respectively (3). Herein, we report the performance of Koch's postulates for P. lygodii on L. japonicum. Excised foliage bearing uredinia from plants collected near Gainesville were placed in a flask, flooded with deionized distilled water, shaken vigorously for a few minutes, and the suspension strained through four layers of cheesecloth. Urediniospores suspended in the filtrate were concentrated to 1.0 × 106 spores/ml, using sedimentation technique, and then misted onto 3-week-old foliage of fully expanded fronds of four juvenile L. japonicum plants grown in pots, until the foliage were completely wet. The plants were then covered with a plastic bag and placed in dappled shade. After 3 days, the bags were removed and the water-filled containers were placed around L. japonicum plants to maintain high ambient humidity. During the remaining 4-week experimental period, the temperature and relative humidity under the shaded areas ranged from 23 to 38°C and 38 to 93%, respectively. The plants were monitored daily for development of symptoms characteristics of P. lygodii. Minute cinnamon-brown flecks appeared on the foliage 20 days after inoculation. Within 3 to 5 days, these flecked areas expanded, erupted, and formed uredinia on the lower surface of the symptomatic foliage. The morphology and size range of the uredinia and urediniospores were the same as those of the P. lygodii applied in this test. This is the first report confirming pathogenicity of P. lygodii on L. japonicum. P. lygodii may be a potential biological control agent of L. japonicum in the Southeast United States.

EFFECTS OF INVASIVE, NON-INDIGENOUS PLANT SPECIES ON ECOSYSTEM PROCESSES: LESSONS FROM FLORIDA

Individual plant species that modify ecosystem properties have traditionally been thought to be uncommon in natural systems. I hypothesize that many invasive non-indigenous species do alter these properties at several scales. The non-indigenous plant species in Florida considered the most invasive by the Florida Exotic Pest Plant Council are examined for this capability through review of the available literature. Out of 31 species total, 12–20 (39–64%) potentially alter the ecosystem properties of geomorphology, hydrology, biogeochemistry, and disturbance. When population-level properties that indicate superior competitive ability of the invading species are examined, 13–24 (42–77%) of the species are included, with the majority of species showing traits capable of modifying natural systems at both ecosystem and community/population scales. This review suggests that ecosystem alteration may be relatively common among invasive non-indigenous species. However, much of the current information is anecdotal. Empirical studies directly examining the effects of species on ecosystem and smaller-scale processes are necessary, and highly invasive species may be particularly appropriate for such research. Further, as non-indigenous species homogenize the global flora, they may also homogenize the local flora by increasing the representation of ruderal species. Where ecosystem processes have been altered, site restoration likely will require both control of the invader(s) and recovery of processes.

The California Exotic Pest Plant Council

The California Exotic Pest Plant Council

The Exotic Pest Plant Council

The Exotic Pest Plant Council