New Hort Resource to Help Support Sustainable Ecological Systems

GRIFFIN, Georgia– University of Georgia researchers with the Center for Urban Agriculture in Griffin are developing a resource tool showcasing common plants that exhibit improved environmental adaptation, and tolerance or resistance to key diseases and pests.

Known as GardenSource, the web-based resource will allow ag professionals, Master Gardeners, homeowners, and nursery and landscape specialists to search through hundreds of herbaceous plants, ornamentals, trees and shrubs that not only showcase their aesthetic qualities, but also exhibit environmental benefits and Integrated Pest Management (IPM) characteristics -- factors important for sustainable ecological systems.

“GardenSource will be available through our county Extension offices, so when people contact the office wanting to know what they should plant for their zone, the tool will provide them with pest resistant options, as well as height and color information,” said Kris Braman, UGA entomologist and director of the UGA Center for Urban Agriculture. “Or someone may have a plant in their landscape and they want to know what to expect. This tool will help them identify management challenges.”

GardenSource is the product of a comprehensive, multi-state Southern Sustainable Agriculture Research and Education (SSARE)-funded project where researchers in Georgia, Florida, Tennessee, Alabama and Mississippi evaluated hundreds of ornamental and turfgrass cultivars. The goal of the project, said Braman, was to increase production and use of low-input, pest resistant plants in the southeastern U.S.

“The synergy for the project came from the informal meetings our group had as members of the Southeast Ornamentals Working Group. We wanted to combine our efforts to identify what we each thought is improved plant material and making that information more easily accessible, as well as help drive the market in making improved cultivars more readily available,” said Braman.

The three-year $180,000 Research and Education Grant-funded project is also helping to expand the efforts of choosing landscape and nursery plants based on Integrated Pest Management strategies.

“Breeders often develop plants for horticultural characteristics, and not for resistance to key diseases or pests. There is so much basic work in that area that hasn’t even been done yet,” said Braman. “With the work we are doing comes the emphasis on education to increase tolerance of moderate pest levels. This is a complex environment and we don’t want to look for simple tactics. There is a need for a small level of insect pressure to support the beneficials. It’s that basic ecological research that will help us build sustainable systems.”

University of Georgia researcher Kris Braman and garden radio/television host Walter Reeves visit the canna lilies demo plots in the UGA Griffin campus Research and Education Garden. Photo credit: Kris Braman

The project final report contains a detailed list of plant cultivars evaluated for their pest resistance and low maintenance. The following are some more notable findings:

• Crape myrtle – Japanese beetle on crap myrtle is recognized as the most widespread and destructive pest of turf, landscape and nursery crops. Researchers evaluated 41 crape myrtle cultivars and found that ‘Lipan’, a tall flowering variety, and ‘Chickasaw’, a dwarf cultivar, performed well with multiple pest resistance.
• Roses – Sales and use of shrub roses has increased dramatically, but information on performance in Southeast is lacking. Researchers in Florida evaluated 12 shrub rose cultivars and after 40 weeks, Knock Out received the highest average cumulative visual quality ratings and largest average cumulative flowering under low maintenance conditions.
• Cana lilies – Twenty-two cultivars of canna lilies were evaluated for potential resistance to the lesser canna lily leafroller and the Japanese beetle. Researchers found an heirloom variety, ‘Maudie Malcolm’, as well as cultivars ‘Striped Beauty’ and ‘Journey’s End’ to exhibit some tolerance to both pests. More importantly researchers found that tall cultivars with red or orange flowers and some red in the foliage were especially vulnerable to leafroller infestations.
• Ornamental grasses – Pennisetum grass selections showed improved disease resistance to leaf spot.

The results of the SSARE-funded study help address critical issues and pave the way for future plant cultivar breeding related to IPM strategies.

“For one”, said Braman, “the work brings more attention to emerging pest problems. Part of the project from Florida involved the evaluation of roses, and one of their target pest problems is the chilli thrip. We can anticipate that this pest will establish in Georgia.”

Additionally, the evaluations give breeders more insight into the biological mechanisms of pest control. Study of lace bug resistance onPieriscultivars found that plants bred for a tougher leaf characteristic were more resistant to the pest. The reason was that the insects had a harder time puncturing the leaf surface, and, as a result, it affected their feeding behavior.

Warm-season turf selections of centipede grass, bermuda grass, St. Augustine grass and zoysia grass were evaluated for tolerance to adult two-lined spittlebug feeding. Among 133 selections evaluated, several showed evidence of potential antibiosis and or/improved tolerance over commercially available cultivars. Photo credit: Kris Braman

GardenSource, anticipated to be ready after the first of the year, is a compliment to the Southern Nursery Integrated Pest Management (SNIPM) Working Group website – an effort that brings together multi-state research and Extension professionals to provide timely IPM information, identify and solve IPM problems, and encourage the use of IPM practices. The crape myrtle evaluations conducted in the SARE study can be found on this website.

Additional participants on the SSARE-funded study (LS06-186), “Increasing Use of Sustainable Plants in Production and Landscape Design,” include David Held, Auburn University; William Klingeman, University of Tennessee; Gary Knox and Russell Mizell, III, University of Florida; Gretchen Pettis, University of Georgia; and Gary Wade, retired University of Georgia professor.

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Published by the Southern Region of the Sustainable Agriculture Research and Education (SARE) program. Funded by the USDA National Institute of Food and Agriculture (NIFA), Southern SARE operates under cooperative agreements with the University of Georgia, Fort Valley State University, and the Kerr Center for Sustainable Agriculture to offer competitive grants to advance sustainable agriculture in America's Southern region.