Increasing Acceptance of Low-Input Landscapes for the Southeast

1995 Annual Report for AS95-023

Project Type: Research and Education
Funds awarded in 1995: $0.00
Projected End Date: 12/31/1999
Matching Non-Federal Funds: $15,980.00
ACE Funds: $36,826.00
Region: Southern
State: Georgia
Principal Investigator:
Dr. Kris Braman
University of Georgia

Increasing Acceptance of Low-Input Landscapes for the Southeast

Summary

This project evaluates the relative costs and likelihood of adoption of several landscape management options.

Objectives
1.) Determine and demonstrate the aesthetic, economic and environmental costs and benefits associated with various pest management methods applied to typical southeastern landscape plants and the interaction with the cultural variable shade.
2.) Determine the feasibility and impediments to acceptance and implementation of alternative pest management approaches in southeastern landscapes.

Approach
A split-split design involving 20 mini-landscapes constructed in the Georgia Station Research and Education Garden was used to evaluate and demonstrate quality of landscapes based on pest resistant plants and on common pest susceptible plant materials under traditional, alternative (scouting-based, targeted biological and biorational), and no intervention pest management programs. The cultural variable of shade vs. no shade was also evaluated for potential influence on susceptibility to pests of landscape plant materials chosen for study.

Sampling at intervals assessed relative pest pressure and plant quality. Pitfall traps were used to collect ground-dwelling beneficial insects and spiders under each regime. Public acceptance of insect-induced injury, as demonstrated during field days was assessed and will form the basis for targeted educational programs designed to modify public expectation of what constitutes acceptable pest pressure. Therefore, we have addressed a major impediment to the implementation of biologically based landscape pest management.

Results
Results from the first (funded) year of study have already revealed the range in pest pressure resulting from differences in management strategy including varying levels of azalea lace bug on azaleas ranging from zero infestation on the resistant Plumleaf azalea to high levels of lacebugs per leaf on our completely untreated plots. Those under traditional chemical management supported only low levels of lace bugs, while those in our targeted pest management plots had intermediate levels. Plant quality assessments of these plants also varied accordingly.

A similar range in infestation levels of two-lined spittlebugs (TLS) on hollies and turfgrass was observed among our treatment regimes. Savannah hollies in untreated plots were heavily infested and new growth especially sustained high levels of damage. Common centipedegrass in these plots was also heavily infested by immature spittlebug nymphs. Beneficial insects and spiders collected in pitfall traps, however, showed little variation in population density among these plots.

Shade effects: The cultural variable shade induced striking differences in insect infestation levels and in plant quality for several of the pest and plant combinations in this study. Spittlebugs, for example were 41x more common in shaded centipedegrass turf than in the full sun plots, consistent with unpublished dogma concerning spittlebug preference for shady sites. Azalea lace bug infestations are reputedly more severe in sunny situations. In our study they were far more common in shaded plots. Recent published studies (Trumble and Denno 1996) revealed similar observations and attribute the usual lower likelihood for understory infestations to the activity of beneficial insects and spiders that are more common in wooded habitats. Ground-dwelling beneficials in this study, however, were slightly more common in the full-sun plots. Foliar beneficials on woody plants were not measured. Spiders and ground beetles were much more often collected in turfgrass than in adjacent bedding plant areas. Ants and other beneficials were more evenly abundant.

Centipedegrass in these 20 mini-landscapes experienced severe winter-kill during the experimental period. Only 16 percent of centipedegrass plots in the shade had recovered by May of this year. Recovery in sunny plots was considerably greater (39 percent) regardless of management regime. When all centipedegrass plots (sun and shade) were evaluated, those receiving targeted management had the best recovery (37 percent), followed by the untreated control plots 925 percent), and the those under a full program (19 percent). Bedding plant quality was also affected by this cultural factor. New guinea impatiens in full sun plots steadily declined in plant quality, resulting in quality measurements 16 weeks post-planting that were only half of those for plants grown in 50 percent shade. Homestead Purple verbena, however, was much less severely affected.

Public acceptance: Surveys during field days of growers and consumers assessed the willingness of those surveyed to purchased azaleas sustaining some lace bug damage and to recommend treatment based on damage levels. The sharpest drop in acceptance occurred with plants that displayed 10 percent damage. Treatment of plants sustaining this level of damage (10 percent) was also recommended by 55 percent of those surveyed. Seventy percent of those surveyed were interested in using pest control strategies that limited pesticide use. A similar percentage expressed willingness to tolerate some damage to limit pesticide use.

Conclusion: A targeted pest management approach achieved an acceptable standard of landscape quality in terms of pest infestations levels and plant quality compared to untreated landscapes and in relation to a full chemical management program. Monitoring activities, however, for this program are time consuming and expensive in terms of trained personnel. Resistant plant materials performed extremely well in reducing the numbers of target pests in these demonstration landscapes. Cultural management considerations were amply illustrated by effects on insect pest pressure and decline in plant quality for plants placed in improper sun or shade conditions. Workshop and field day participants expressed willingness towards an increased tolerance of insect pest pressure and low levels of damage to achieve the goal of reduction in pesticide use.

December 1996.

Collaborators:

W.J. Florkowski

Dept. of Agr. & Applied Economics, U of Georgia
R.D. Oetting

Dept. of Entomology, U of Georgia
J.G. Latimer

Dept. of Horticulture, U of Georgia
M. Prinster

TruGreen ChemLawn
T. Eckberg

TruGreen ChemLawn