Stephen F. Enloe and Ken Langeland

Plants provide us with food and fiber, decorate our yards and gardens, and provide habitat for wildlife. However, when plants grow where they are not wanted, we call them weeds. To homeowners, weeds may be unwanted plants in lawns or gardens. To farmers, weeds are plants that interfere with raising crops or livestock. To biologists who manage natural areas, weeds are plants that interfere with the functions of natural communities.

Air potato (Dioscorea bulbifera) has been recognized as a serious invasive plant species in Florida since the early 1990s. It was listed as a Category 1 invasive plant in 1993 by the Florida Invasive Species Council and was subsequently added to the Florida Noxious Weed List by the Florida Department of Agriculture and Consumer Services in 1999 (5b-57.007 FAC). Plants on the Florida Noxious Weed List may not be introduced, possessed, moved, or released without a permit.

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Edward F. Gilman, Dennis G. Watson, Ryan W. Klein, Andrew K. Koeser, Deborah R. Hilbert, and Drew C. McLean

Long-favored for use in erosion control along beaches, Australian-pine tree is now outlawed in many parts of Florida due to its invasive nature, rapid growth rate, and
non-native status. It is not a true pine tree and is not related to the pines. A straight, upright tree capable of reaching 70 to 90 feet in height and possessing rough, fissured, dark gray bark, Australian-pine has what appear to be long, soft, gray green needles but these “needles” are actually multi-jointed branchlets, the true leaves being rather inconspicuous. These “needles” sway gently in the breeze and give off a distinctive, soft whistle when winds are particularly strong. The insignificant flowers are followed by small, spiny cones, less than 1⁄2-inch-long.

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K. T. Gioeli, S. F. Enloe, C. R. Minteer, D. M. Lieurance, and K. A. Langeland

This publication presents management recommendations for Schinus terebinthifolia, the Brazilian peppertree. It contains information about Brazilian peppertree biology, herbicide application techniques, and the status of biological control. The intended audience includes homeowners and land managers primarily in coastal areas of central and south Florida where Brazilian peppertree is prevalent.

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Sherry L. Larkin and Charles M. Adams

The Gulf of Mexico Alliance (GOMA) sought information on how best to (1) co-educate the management and scientific communities on the economic impacts of harmful algal blooms (HABs) and new methods to better capture HAB economic and social impacts, and (2) move the communities toward a standardized way of measuring the economic ramifications of HABs (Figure 1). This information is critical to assessing the economic risk that HABs pose to coastal communities and thereby help to direct the appropriate level of resources toward investigating potential prevention, mitigation, and control strategies. In the United States, federal programs include the interagency Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) Program; the NOAA Monitoring and Event Response for Harmful Algal Blooms Program (MERHAB); and the NOAA Prevention, Control, and Mitigation of Harmful Algal Blooms Program (PCM HAB).

To address these needs, this factsheet first summarizes the existing literature that attempts to measure some of the economic consequences associated with harmful algal blooms (HABs). This is accomplished by using the recent report by Adams and Larkin (2013) that contains an annotated bibliography of both peer-reviewed and “grey” (i.e., unreviewed) research papers (available online at http://www.fred.ifas.ufl.edu/pdf/Adams-Larkin-LitRev-April2013.pdf). In addition, this factsheet describes the methodologies that have been used to measure economic losses; reviews the types and sources of data used; discusses the complexities of addressing the scope of HAB events; analyzes the focus of previous studies in terms of types of HABS examined; and identifies research gaps.

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Of the nearly 4,000 plant species growing in the wild in Florida, about 1,000 are non-native or "exotic." Most of them are not a problem. However, about 130 plant species are considered invasive.

An invasive plant is a non-native plant that causes harm to the environment, economy, or public health. In Florida, approximately 24 aquatic plant species are currently considered invasive.* Many of them have been introduced largely from global commerce and trade (imported aquarium and water garden plants and ballast water from ships) and also from recreational boat travel. Once introduced into a waterbody, plants are easily spread by boats and other recreational equipment.

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Stephen F. Enloe and Ken Langeland

More than one-half of Florida’s land area is in agricultural or urban land uses, and native habitats are continually being lost. Continued urbanization is an inevitable consequence of increasing population, and food production by agriculture is essential. However, preserving and protecting Florida’s native habitats for historical significance and to protect native species, water quality, and water quantity is also essential. Natural areas have been designated on federal, state, county, city, and private lands.

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Developed by members of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Invasive Species Council (ISC), these terms are applicable to animal and plant species. The UF/IFAS Center for Aquatic and Invasive Plants (CAIP) has chosen to highlight aquatic and terrestrial plant examples of each of the terms relevant to Florida.

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K. A. Langeland, S. F. Enloe, and J. P. Cuda

Melaleuca (Melaleuca quinquenervia) is a well-known tree native to Australia. It was introduced into the United States in 1887 for use in landscaping, agricultural windrows, highway plantings, and soil stabilization. Although it initially proved to be useful for many of these purposes, it quickly began to spread from plantings and invaded many natural areas of southern Florida. Aided by wind-dispersed seed, aggressive growth, and a lack of natural enemies, melaleuca infested almost 500,000 acres by 1994. Extensive stands occurred in the Everglades Big Cypress National Preserve, and Arthur R. Marshall Loxahatchee National Wildlife Refuge.

Melaleuca forms dense stands that completely transform the character of natural habitats. It displaces native plant communities and associated wildlife, disturbs natural water flow, and alters soil conditions. Areas once home to endangered species such as the Cape Sable seaside sparrow (Ammodramus maritimus mirabilis), wood stork (Mycteria americana), and Florida panther (Puma concolor coryi) are no longer suitable because of melaleuca invasion. When fire occurs, melaleuca trees burn at extremely high temperatures, causing additional environmental damage. Melaleuca may have a strong negative impact on migrating birds, which depend on native plants for seeds, fruits, and insects during migration. In addition, dense melaleuca stands can strongly restrict the use of parks and recreation areas, negatively impacting ecotourism in Florida.

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Stephen F. Enloe, Kenneth A. Langeland, and Jeffery Hutchinson

There are many well-known invasive plants in Florida such as melaleuca, Brazilian peppertree, and cogongrass. Each of these has been present for over 80 years and has widespread negative impacts within the State. However, a species known as Old World climbing fern has greatly increased over the last thirty years in Florida and may become the greatest invasive plant threat to Florida’s natural areas. Old world climbing fern, hereafter referred to as OWCF, is an aggressive, twining fern that forms dense smothering mats over trees, shrubs, and other vegetation (Figure 1). It spreads by wind-dispersed spores and is often found in very remote areas, making containment very difficult. This publication describes the biology and ecology of this invasive plant and provides management options for both public land managers and private landowners.

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Paul T. Madeira · F. Allen Dray Jr. · Philip W. Tipping

Understanding the origins and genetic relationships of invasive, non-native species is critical to informing conservation and management practices. Pistia stratiotes is one such species—a pantropical floating plant that is problematic in many regions of the world, including Florida, USA. Questions surrounding the origins of P. stratiotes populations in Florida and elsewhere prompted a molecular investigation using five chloroplast and one mitochondrial DNA sequences. A total of 154 samples were collected from 14 countries. The sequence data was analyzed using haplotype network analysis, maximum likelihood phylogenetics and species delimitation tools. These data show that P. stratiotes comprises a minimum of seven distinct haplotypic clades worldwide, three of which differ enough to likely represent different species. Florida, which was more heavily sampled than other regions of the world, contains four of the clades—one of which shows evidence of being pan-Caribbean with sufficient variation to suggest regional (including Florida) nativity. A second clade, present in the U.S. Gulf States and California, may be native within this range, however more sampling is needed to fully describe its distribution and nativity. Another clade, predominant in southern Florida and the St. Johns River, likely originated in South America. Results are discussed in the broader context of the effects of cryptic species on weed management, including biological control efforts.

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A GLIMPSE INTO THE ROBUST REGISTRATION PROCESS FOR HERBICIDES USED IN PLANT MANAGEMENT

Plant management oftentimes requires the use of herbicides in both aquatic and terrestrial systems. Herbicides are a type of pesticide intended for preventing, destroying, repelling, or mitigating problematic or pest plants.

Before a herbicide is able to be distributed or sold in any U.S. market, the manufacturer must put the product through an extensive and expensive registration process that ensures it meets federal safety standards. These safety standards are regulated under two laws: the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug, and Cosmetic Act (FFDCA) to protect human and environmental health.

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MEASURING SHORT-TERM CHANGES IN SHOOT LENGTH TO DESCRIBE INVASIVE POTENTIAL

It has been well documented that one common characteristic among many invasive plants is their ability to grow. Hydrilla (Hydrilla verticillata) in particular, is notorious for growing into dense mats in many freshwater systems within Florida and across the United States.

The statement, “hydrilla can grow an inch a day” (Langeland, 1996) is often repeated. In this study, U.S. Army Corps researchers, stationed at the UF/IFAS Center for Aquatic and Invasive Plants, tested this statement.

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Lyn A. Gettys

Waterhyacinth is a free-floating aquatic plant that grows throughout the year in southern Florida but undergoes winter dieback in northern parts of the state. The species can survive moderate freezes but requires temperatures above 50°F to produce new growth. The transportation, importation, collection, possession, cultivation, or sale of waterhyacinth (a Noxious Weed) is illegal in Florida (FDACS DPI 2020), but the species is still occasionally available for purchase from some farmers’ markets, yard sales, aquarium supply stores, aquatic plant nurseries, and Internet sources in other states.

Waterhyacinth is native to the Amazon River in Brazil and has invaded ecosystems throughout the world. The first documented broad introduction of waterhyacinth to the United States occurred at the Southern States Cotton Expo in New Orleans in 1884, although it is probable that the species was cultivated as a water-garden plant for many years prior to that. Visitors to the Expo were given waterhyacinth plants as souvenirs, and many of these plants found their way into the waters of Louisiana, Texas, and Florida (Klorer 1909). Anecdotal reports state that “Mrs. Fuller,” an Edgewater, Florida, resident and visitor to the Expo, was entranced by the beautiful, showy flowers of this Amazonian native (Figure 1) and brought plants back to her water garden near the St. Johns River. The plants grew abundantly, and the backyard water gardener decided in 1890 to share her “bounty of beauties” with others by tossing her extra plants into the St. Johns River near Palatka.

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