Increasing use of sustainable plants in production and landscape design

Increasing use of sustainable plants in production and landscape design

Summary

Research was conducted in Alabama, Florida, Georgia and Tennessee during 2008 to identify optimal ornamental plant material for the southeastern US and to evaluate green industry professional adoption or acceptance of pest-resistant plants. Extensive evaluation of herbaceous and woody ornamentals for resistance to key pests has identified plants to recommend for their reduced pesticide, fertilizer or water requirements. Among surveyed lawn care and landscape maintenance professionals, insect and disease resistant plants are largely anticipated to be beneficial both to business performance and to client satisfaction with plants in managed landscapes.

Objectives/Performance Targets

Research during the 2007-2008 year addressed objectives 1 and 3:

1) Identify optimal plant material
3) Enhance the likelihood that that resistant plants will be specified

Research to identify pest resistant and other stress tolerant plant material was conducted in Georgia, Florida and Alabama during 2008.

Surveys and interviews were conducted in TN and GA and analyzed in TN to better understand industry willingness to adopt and recommend use of pest resistant plants

Accomplishments/Milestones

Research was conducted to identify pest resistant and stress tolerant plant material for the southeastern US.

Susceptibility of holly varieties to Florida wax scale was evaluated by David W. Held, Auburn University. In April and May, 33 taxa of potted hollies were purchased from local nurseries. Each taxon is represented by six plants (replications). Plant taxa were selected to provide varieties within four landscape use groups; trees, large shrubs, medium shrubs, and small shrubs. Each landscape use group has a minimum of five varieties. The intended purpose of the groupings is for easier incorporation into the plant use database, also an objective of this project. For example, if this research determines that Ilex crenata ‘Hoogendorn’ (small shrub group) is susceptible then a resistant variety in the same use group would be suggested by the software as a substitute. In mid-May, plants were potted into 3 gal pots using a bark-sand mixture and fertilized with 17-5-11, slow-release fertilizer (Harrell’s, Lakeland, FL). Potted plants were placed 0.9 m apart on a 14.6  14.6 m irrigated, research space. On May 12, stems from a planting of hollies infested with Florida wax scale (FWS), Ceroplastes floridensis, in Mobile, AL were harvested and shipped overnight to Auburn. Since there is no way to standardize the number of crawlers per plants, cuttings were graded by the number of adults per cutting. Therefore, plants within each replicated would be infested with a similar number of gravid females. Stems were tethered into each potted plant using parafilm. No plant received a cutting with less than 10 gravid females. Each FWS female typically has >500 eggs (Held, unpublished data) providing ample crawlers for infesting each plant. Just before the plants were infested, a sample of foliage was collected for nitrogen tissue analysis. Another set of foliage was also collected to determine water content, leaf toughness, leaf thickness, and leaf area. These variables will characterize the plant at the time of crawler hatch. Data are being compiled and will soon be analyzed. In June, 2009, a sample of foliage will be taken the number of crawlers per leaf will be determine for each plant. In Aug, another sample of foliage will be taken to determine the fecundity of gravid females. Crawler survivaldensity or females fecundity are important determinants in susceptibility of hollies to FWS.

Pest-resistant plant projects conducted at University of Georgia by Kris Braman included:

Susceptibility of Canna Lilly cultivars to canna lilly leafrollers and Japanese beetles was conducted at three locations in Georgia during 2008 and will be repeated in 2009. Twenty two cultivars were assessed for their ability to withstand the most problematic insect pests of the region affecting these popular ornamental plants.

The final year of a field trial evaluating crape myrtle infestation by Japanese beetles was completed during 2008 in a study comparing 41 cultivars of varying flower, foliage and height classes in Georgia.

The influence of fertilizer on relative susceptibility of hemlock species known to vary in susceptibility to the invasive hemlock wooly adelgid was examined in Georgia during 2008 and continues during 2009.

Trials on knockout roses were conducted at University of Florida during 2008 by Gary Knox and Russ Mizell.

Lawn care and landscape maintenance professional acceptance of insect- and disease-resistant ornamental plants was investigated using surveys by Bill Klingeman, University of Tennessee. While lawn care and landscape maintenance professionals appear increasingly willing to use Integrated Pest Management (IPM) strategies and adopt non-chemical pest management alternatives into management practices, the opinions of landscape management professionals have not been assessed regarding anticipated influences of increased availability and use of insect- and disease-resistant ornamental plants on either grounds management activities, client satisfaction or business profitability. If these professionals are unwilling to advocate installation of ornamental host plants that are resistant to certain pests or diseases, market success of such plants will be limited. To address this knowledge gap, we surveyed landscape management professionals to categorize their perceptions about insect- or disease-resistant ornamental plants and qualified their beliefs in relation to both personal and firm demographics. A total of 391 completed surveys were received from TN, FL and GA participants. Data analyses revealed that lawn care and landscape maintenance professionals largely believe that insect- and disease-resistant plants will benefit their businesses and should result in increased client satisfaction. Only about 4% of respondents stated concern that business would incur at least some negative effect if pest resistant plants were made more available or used in greater numbers in client landscapes. On average, respondents believed that 60% or more of plants within a given client landscape must resist insect pests or plant diseases to affect a decrease in company profits. Respondents also expected that the required number of site visits to client landscapes would remain unchanged and that at least moderate reductions in insecticide and fungicide use would result if insect- and disease-resistant ornamental plants were used more widely in client landscapes.

Impacts and Contributions/Outcomes

Pest resistant and low input plants identified in this project will impact environmental stewardship by reducing the amount of pesticides, water and fertilizer from production through final landscape establishment.

Host plant resistance has not previously been specifically addressed with regard to green industry professional adoption or acceptance of integrated pest management components. Among surveyed lawn care and landscape maintenance professionals, insect and disease resistant plants are largely anticipated to be beneficial both to business performance and to client satisfaction with plants in managed landscapes.

Collaborators: