Optimizing Plant Health and Pest Management of Lagerstroemia spp. in Commercial Production and Landscape Situations in the Southeastern United States: A Review1

Lagerstroemia is a genus of plants comprised of deciduous shrubs or small trees native to China southward into Southeast Asia. L. indica, the oldest and most widespread species in cultivation in the United States, has been cultivated as an ornamental for centuries and was introduced to the Southeastern U.S. over 175 years ago. Much has been disseminated on the culture and commercial production of crapemyrtle species and cultivars; including plant forms and function, adaptability to macro and micro environment, growth and fl oral characteristics, and commercial production and landscape culture and maintenance. Since the introduction of L. indica in the United States, L. fauriei, L. subcostata and L. limii have also been introduced. However, since the mid 1970s, interspecifi c hybrids between L. indica × L. fauriei comprise the majority of new cultivar introductions. Breeding efforts have resulted in 133 commercially available cultivars as of December 2011 that include cultivars with ever improving form and fl owering, new fl ower colors, ornamental bark, ornamental foliage, and disease tolerance. However, there is a wide range among cultivars of tolerance to key pests and diseases such as powdery mildew, Cercospora leaf spot, fl ea beetle and Japanese beetle. A large number of pests and plant pathogens also negatively affect crapemyrtle health including granulate ambrosia beetle, crapemyrtle aphid, bark scale, bacterial leaf spot, sooty mold and soil-borne root and crown diseases. This review focuses on crapemyrtle culture, in both commercial and landscape settings, with an emphasis on optimizing plant health through the discussion of major abiotic and biotic stressors and cultivar variation in tolerance to these stressors. Index words: crapemyrtle, IPM, ornamental pests. Species used in this study: Lagerstroemia indica; Lagerstroemia speciosa; Lagerstroemia fauriei; Lagerstroemia subcostata; Lagerstroemia limii; and Lagerstroemia indica × fauriei. 1Received for publication January 22, 2012; in revised form May 4, 2012. We would like to thank Dr. William (Bill) Klingeman, Dr. Amy Fulcher and Justin West for reviewing this manuscript prior to submission and the Southern Region IPM Center for funding support for the project titled Enhancing Nursery Crop Research and Extension with a Multi-State Working Group that led to the construction of this manuscript. 2University of Georgia, Department of Horticulture, 211 Hoke Smith Bldg., Athens, GA 30602. [email protected]. 3University of Georgia, Department of Entomology, 1109 Experiment St., Griffi n, GA 30223. [email protected]. 4University of Georgia, Department of Plant Pathology, 3313 Miller Plant Sci. Bldg., Athens, GA 30602. [email protected]. 5University of Florida, North Florida Research and Education Center, 155 Research Road, Quincy, FL 32351. gwknox@ufl .edu. Signifi cance to the Nursery Industry Since its introduction over 175 years ago, Lagerstroemia spp. and cultivars have been major horticultural crops in the ornamental nursery industry, both in container and fi eld settings. In the southeastern United States, plants are commercially grown and sold in many salable sizes from small containerized liners to large fi eld produced specimens and may be in production at nurseries for several years before being marketed and sold. Because of the durability of crapemyrtle, plant health and pest management of crapemyrtle is sometimes overlooked in both landscape and production settings. However, there are several biotic (insects and diseases) and abiotic (e.g. low temperature) factors that can signifi cantly and negatively impact the health of crapemyrtle and in some cases lead to mortality if not correctly identifi ed and properly controlled. This review provides a comprehensive overview of crapemyrtle culture in production and landscape environments, focusing on environmental factors and pests that lead to signifi cant injury. This article will be directly applicable to green industry professionals who sell, install and maintain crapemyrtle in commercial and landscape settings.