Dactyloctenium aegyptium (crowfoot grass).

Producing large quantities of seeds, D. aegyptium is a pioneer grass that quickly colonizes disturbed areas with light sandy soils, often near to coasts or where water accumulates. It is a common component of weed floras throughout the tropics but is rarely reported as an aggressive weed on its own. It is not on federal or state noxious weed lists in the USA and is not recorded on the ISSG database but is recorded by PIER (2016) as invasive on a number of Pacific and American islands including French Polynesia Islands, Micronesia, the Northern Mariana Islands and Hawaii. It is also listed as invasive on islands in the Mediterranean, the USA, Mexico, Costa Rica, Puerto Rico, Virgin Islands and the Lesser Antilles (Vibrans, 2009; Florida Exotic Pest Plant Council, 2011;Chacón and Saborío, 2012; Burg et al., 2012; Rojas-Sandoval and Acevedo-Rodríguez, 2015; DAISIE, 2016; USDA-NRCS, 2016).

Breynia disticha (snowbush).

B. disticha is considered as an invasive shrub to small tree in USA (Florida and Hawaii), Guinea, The British Indian Ocean Territory, Niue and Cuba (Oviedo Prieto et al., 2012; Swearingen and Bargeron, 2016; PIER, 2017). The species invades areas close to where cultivated by root suckers (PIER, 2017). In Cuba it is considered as a transformer species, without further details (Oviedo Prieto et al., 2012). It is regarded as an invasive species in Florida-USA by Swearingen and Bargeron (2016), although it is not in the Florida Exotic Pest Plant Council's list of invasive plant species (Florida Exotic Pest Plant Council, 2017). At Dave's Garden (2017) it is considered by the community as an invasive species in southern Florida, having the ability to spread quickly from roots in damp soils. It is not considered as an invasive species for Florida by Gilman (2014). In Hawaii-USA it has escaped from cultivation and is spreading vegetatively around abandoned homesites in Hawaii (PIER, 2017). In Guinea, the green-form of B. disticha is considered as an invasive species along the roadsides, in secondary thickets over many hectares, at the edge of a mangrove and in woodlands (Cheek et al., 2013). As its been found in areas with no evidence of former cultivation, apparently spreading through seeds. It has been collected in fruit at one of the sites. No details about its invasiveness are given for the British Ocean Territory and Niue.

Dactyloctenium aegyptium (crowfoot grass).

Producing large quantities of seeds, D. aegyptium is a pioneer grass that quickly colonizes disturbed areas with light sandy soils, often near to coasts or where water accumulates. It is a common component of weed floras throughout the tropics but is rarely reported as an aggressive weed on its own. It is not on federal or state noxious weed lists in the USA and is not recorded on the ISSG database but is recorded by PIER (2016) as invasive on a number of Pacific and American islands including French Polynesia Islands, Micronesia, the Northern Mariana Islands and Hawaii. It is also listed as invasive on islands in the Mediterranean, the USA, Mexico, Costa Rica, Puerto Rico, Virgin Islands and the Lesser Antilles (Vibrans, 2009; Florida Exotic Pest Plant Council, 2011;Chacón and Saborío, 2012; Burg et al., 2012; Rojas-Sandoval and Acevedo-Rodríguez, 2015; DAISIE, 2016; USDA-NRCS, 2016).

Russelia equisetiformis (firecracker plant).

Russelia equisetiformis is a shrub that is widely cultivated around the world (PROTA. 2016). It is listed as an invasive and a transformer species in Cuba (Oviedo Prieto et al., 2012). In Oceania it is reported as an invasive species that has escaped from cultivation in Fiji, French Polynesia, Kiribati, New Caledonia, Niue and Palau (PIER, 2016). In Florida it is regarded by Florida's Exotic Pest Plant Council as a category III species; a widespread species that has the potential to form dense monocultures, primarily on disturbed sites (FLEPPC, 1993). It is regarded as a low risk species in Hawaii (Bezona et al., 2009).

Manilkara zapota (sapodilla).

M. zapota, commonly known as sapodilla, is an evergreen tree, 5-20 m tall, with a round, dense crown. Its native range encompasses Central America, Mexico and the West Indies, but it is now widely cultivated for its fruit to a greater or lesser extent in tropical and subtropical lowlands worldwide. It is an important fruit tree all over South-East Asia, grown in home gardens, orchards and plantations. The largest producers of sapodilla fruit are India, Thailand, the Philippines and Malaysia, but it is also grown commercially elsewhere in Asia, South and Central America, and Florida in the USA. Escapes from plantations have caused the species to be classed as a moderately invasive weed in the tropics (Binggeli et al., 1998), although in the USA it is of particular concern in southern and central Florida, where it is classed as a Category I invasive displacing the native flora (Florida Exotic Pest Plant Council, 2001). It is also listed as invasive in Trinidad and Tobago (Trinidad and Tobago Biodiversity, 2017). Trees cast dense shade, making it difficult for other plants to survive in the understorey. Seedlings also grow very densely, inhibiting the establishment of native plant species.

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

Napiergrass 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.

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