Invasive Plant Science and Management 2010 3:482–488 Notes and Commentary Identification and Control of Invasive Privets (Ligustrum spp.) in the Middle Southern United States Victor Maddox, John Byrd, Jr., and Brett Serviss* The identification of privet in the middle southern United States can be difficult. Because most introduced species of privet can be invasive, and recent mapping projects seek location and species population data, proper identification is important. Without proper identification of privet species, data on species distributions and other pertinent information regarding invasiveness could lead to improper conclusions. Currently, information on privet identification is scattered throughout a number of reference materials. The purpose of this publication is to assist with the proper identification of escaped privet species, and suggest management options. Nomenclature: Fosamine ammonium; glyphosate; hexazinone; imazapyr; metsulfuron; triclopyr; 2,4-D; 2,4-DP; Amur privet, Ligustrum obtusifolium Sieb. & Zucc. var. suave (Kitagawa) Kitagawa (Syn. L. amurense Carrie`re); border privet, Ligustrum obtusifolium Sieb. & Zucc. var. obtusifolium; California privet, Ligustrum ovalifolium Hassk.; Chinese privet, Ligustrum sinense Lour.; common privet, Ligustrum vulgare L.; glossy privet, Ligustrum lucidum Ait.; Japanese privet, Ligustrum japonicum Thunb.; waxyleaf privet, Ligustrum quihoui Carrie`re. Key words: Invasive species, management. Since the 1700s, at least nine species of privets have been Thunb.) is native to Korea and Japan. The most common introduced into the United States; it is probable that all species in the southern portion of the middle southern were introduced as ornamentals. They have been very region is Chinese privet, although Amu, border, California, successful as ornamentals and continue to be marketed for common or European, glossy, Japanese, and waxyleaf or such purposes. In addition to these species, there are many Quihoui privets also have escaped (USDA–NRCS 2009). hybrids and cultivars (Dirr 1998). However, in the United In the southern United States, most privet species readily States all privets are nonnative and most have escaped from escape cultivation and naturalize in areas surrounding sites cultivation. They are native from Europe to North Africa of cultivation. Chinese, common, and waxyleaf privet form and east to Asia and Australia. Amur [Ligustrum dense monocultural stands once established. obtusifolium Sieb. & Zucc. var. suave (Kitagawa) Kitagawa], Most species are widespread in cultivation, and thus are Chinese (Ligustrum sinense Lour.), and waxyleaf (Ligustrum not regulated by noxious weed regulations. However, quihoui Carrie`re) privets are native to China; border Chinese privet is included on all state invasive species lists (Ligustrum obtusifolium Sieb. & Zucc. var. obtusifolium) in the southeast (Miller et al. 2004). It is considered one of and California (Ligustrum ovalifolium Hassk.) privets are the top ten weeds in Alabama and Georgia, and a Category native to Japan; common or European privet (Ligustrum 1 invasive plant in Florida. In Kentucky, South Carolina, vulgare L.) is native to Europe and North Africa; glossy and Tennessee, it is a severe threat and is included on state privet (Ligustrum lucidum Ait.) is native to China, Korea, invasive plant lists in Mississippi and Virginia. Common and Japan; and Japanese privet (Ligustrum japonicum privet is a Rank 1 (severe) threat and Japanese privet is a Rank 2 (significant) threat in Tennessee natural areas DOI: 10.1614/IPSM-D-09-00060.1 (Miller et al. 2004). * Postdoctoral Associate, Geosystems Research Institute, Mis- sissippi State University, Mississippi State, MS 39762; Extension Description of Privet Species Research Professor, Mississippi State University, Mississippi State, MS 39762; Associate Professor of Biology, Henderson State There are approximately 40 species of Ligustrum which University, Arkadelphia, AR 71999-0001. Corresponding author’s are native from Europe to Asia and northern Australia. E-mail: [email protected] Privets are in the Oleaceae family, and thus generally are 482 N Invasive Plant Science and Management 3, October–December 2010 Interpretive Summary Several species of privet are invasive in the middle southern United States. Recent mapping projects seek location and species population data; thus proper identification is important. Without proper identification of privet species, data on species distributions and other pertinent information regarding invasiveness could lead to improper conclusions. Currently, information on privet identification is scattered throughout a number of reference materials. The authors believe the information provided in this publication will assist with the proper identification of escaped privet species. Management of invasive species is a valuable tool. Currently, management options also are scattered throughout a number of reference materials. Although various researchers continue to conduct privet control studies, current management suggestions for privet are provided in this publication. recognized as a group by their simple, opposite (rarely whorled) leaves with entire margins (Figure 1) and four- lobed corollas (Figure 2). Flowers are white in dense or open, terminal or subterminal axillary panicles (Figure 2). The fragrance of the flowers is loved by some, but hated by others. Privets produce drupes containing one to four seeds. Although some species are very similar in appearance, most can be identified to species without extreme difficulty. Amur, border, California, common, and waxyleaf privets Figure 2. Chinese privet (Ligustrum sinense)(A)alonga fencerow on a forest margin; (B) flowers in dense panicles; (C) foliage showing leaf shape and arrangement; (D) flowers showing four-lobed corollas and exerted purple stamens; and (E) fruit in winter showing color and shape of drupes (photos by Victor Maddox, MSU–GRI). are similar in appearance to Chinese privet, especially at a glance. A closer look is generally required to separate this group of species. In summer, all generally have leaves; thus deciduous species may look similar to evergreen species during the growing season. There are some distinct groups, but most privets have relatively small leaves. Glossy and Figure 1. Leaf comparison of different privets. Left to right are: Japanese privets have larger leaves compared to other privet Border privet (Ligustrum obtusifolium var. obtusifolium), Amur species discussed in this publication (Figure 1); both are privet (L. obtusifolium var. suave), California privet (L. evergreen. Border and common privet are deciduous, ovalifolium), waxyleaf privet (L. quihoui), Chinese privet (L. although other species such as Amur, California, Chinese, sinense), Japanese privet (L. japonicum), and glossy privet (L. and waxyleaf privet can be deciduous in the northern parts lucidum). Images taken from material collected on same site in of the middle southern United States. Amur privet, border Webster County, Mississippi on February 5, 2009. Note privet, California privet, Chinese privet, common privet, discoloration of border and Amur privet, a deciduous character- and waxyleaf privet are escaped species with smaller leaves istic; plants had very few remaining leaves. Common privet (L. (Figure 1). A key to privet species escaped in the MidSouth vulgare) had no leaves (deciduous) and is not shown (photo by is provided to facilitate identification (Appendix 1). Other Victor Maddox, MSU–Geosystems Research Institute). keys for various privet species can be found in Bailey Maddox et al.: Privet Identification and Control N 483 484 chemical defense against herbivores (Konno et al. 1999). It the stems. drupes, typically are formedunlike in dense Chinese clusters that privetbe hang hook-shaped (Figure on on 2). speciesshape such The as with glossy privet fruits, privet speciesare (Figure which (Table ovoid 3), 1). are to Occasionally globoseblue fruit (Figure or can 2), black by butJuly winter vary to (Figure in 2). March. both Fruit Immature size of and fruits Chinese privet areflowers. green then turn(Table dark 1). Butterflies andcorolla other in insects Chinese frequently (Figure0.4 visit 2), in) the (Table but 1). varyvaries Stamens with with are privet species typically species and exertedFlowers beyond ranges the from range 3.5 from toCalifornia, 10 sessile mm Chinese, (0.14 to to reflowering pedicellate. and also Corolla can occur Japanese length privets in certain privets in species suchtypically in the as starts Amur, in the Carolinas JuneFigure for (Radford fall. 3 Amur, et California, withbut and al. flowering Japanese glossy varies 1968).produces with and flowers species Some (Table fromfor 1) Japanese April as identifying to depicted privet. June privetlength, in (Figure and species. Flowering anther 2; position Chinese Table canflower 1), be privet position, important corolla characteristics abundantly tubevarious to corolla species lobe length, (Table corolla 1; Appendixillustrates 1). some minor Flowering differences. size time, and shapecompared to on glossy or allmidvein Japanese small-leafed privets. (midrib) Leaf species, beneath. shapesare vary Leaf but dull in to blades Figure lustrous green are 1 3.5 above cm and relatively (0.5 paler thin green to with 1.4rounded a in) tip hairy long (Figure and 1.0 2).rarely to Leaves 3.0 whorled, are cm wide.angles approximately and Leaves from 1.25 to typically thewith main light-colored ovate trunk. lenticels.