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Crapemyrtle Tests Yield Four New Selections With Commercial Potential

Current crapemyrtle cultivars are susceptable to a variety of diseases which detract from their appearance, and make sales more difficult.

Current crapemyrtle cultivars are susceptible to a variety of diseases such as this new bacterial spot disease caused by Xanthomonas sp., which detract from their appearance and make sales more difficult.

Four new crapemyrtle selections (“Lagerstroemia limii (OP1)”, “L. limii (OP2)”, “L. subcostata (MS))”, and “L. subcostata (CA)”) were evaluated and compared to 11 commercially available cultivars (“Arapaho”, “Carolina Beauty”, “Fantasy”, “Miami”, “Natchez”, “Osage”, “Party Pink”, “Red Rocke”, “Rhapsody in Pink”, “Tuscarora” and “White Chocolate”) for disease resistance by a multi-state team as part of a two-year project. The objective was to improve selections wholesale growers can commercially offer to consumers.

“Crapemyrtles have been propagated in the U.S. for over 150 years and have a long established track record as a popular landscape shrub,” said Dr. Mathews Paret, plant pathologist at the UF/IFAS North Florida Research and Education Center (NFREC) in Quincy, Florida. “While they are known for their colorful and long lasting flowers, unfortunately there are some disease issues which mar the natural beauty of this plant,” he said.

Almost three million crapemyrtles worth more than $42.8 million are domestically produced each year in the U.S. This genus is an important sector of the state of Florida’s commercial horticulture industry with production worth $7.2 million.

Dr. Paret and Dr. Gary Knox, also at the NFREC evaluated the resistance of various crapemyrtle germplasms to diseases in 2011 and 2012. The replicated field trials compared the performance of four new cultivars against eleven crapemyrtles which are currently grown at many nurseries.

A new disease on crapemyrtle, bacterial spot caused by Xanthomonas, was of particular interest. Other disease resistance traits evaluated included Cercospora leaf spot caused by Pseudocercospora lythracearum, powdery mildew caused by Erysiphe australiana, sooty mold and environmental diseases including Oedema and Rabbit Tracks.

The commercially available crapemyrtle cultivars “Arapaho,” “Carolina Beauty,” “White Chocolate,” and “Red Rocke” were resistant to all diseases tested for except bacterial spot. The new selections, “L.limii (OP1)” and “L. limii (OP2),” showed a higher resistance to all diseases except for Cercospora leaf spot.

The crapemyrtle cultivars “Fantasy,” “Osage,” and “Party Pink” were resistant to all six diseases in the 2011 and 2012 assessment period.  The new selections, “L. subcostata (CA)” and “L. subcostata (MS),” were highly resistant to bacterial spot, powdery mildew, sooty mold, and Rabbit Tracks.

Crapemyrtle cultivars “Natchez” and “Miami” were resistant to all bacterial and fungal diseases and Oedema.  “Rhapsody in Pink” and “Tuscarora” showed resistance to all diseases except bacterial spot.

Studies were also conducted in two Alabama locations. Funding for the project came from the Florida Nursery, Growers and Landscape Association (FNGLA).

Out-of-state project collaborators were Dr. Cecil Pounders, USDA-ARS and Dr. Austin Hagan, Auburn University.

Check Dr. Mathews Paret’s U-scout page for a picture database on all diseases of crapemyrtle in Florida: U-scout, Crapemyrtle Diseases – Plant Pathology Lab, UF/IFAS NFREC


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