Pest Index: A New Approach to Establishing Thresholds for Pest Management in Woody Landscape Plants1

Pest index, a new approach to categorizing the threat posed by an organism to woody plants, is proposed to assist plant managers in establishing treatment thresholds for pests of woody plants. The need for such a tool is based on the incredible diversity of pests of woody plants and the lack of experimental data establishing such thresholds. The pest index is computed using information about the detectability, damage potential, and ease of control of various pest groups. Values of the pest index are proposed for a variety of pest groups, but can be readily adapted to other groups not considered (or modifi ed for particular pests that differ signifi cantly from others in the broad groupings listed here). Using the pest index should allow plant managers to deal effectively with pests that are likely to pose serious threats to trees and shrubs instead of simply applying pesticides whenever a pest is detected. Thus, the pest index should foster the adoption of integrated pest management (IPM) in ornamental settings. Index words: pest thresholds, integrated pest management. Signifi cance to the Nursery Industry A new approach is proposed for prioritizing management of pests of woody plants in landscapes. A pest index, which is calculated by considering the detectability, damage potential, and the ease with which pests can be controlled, is proposed as a measure of the threat posed by a number of groups of insect and mite pests to trees and shrubs. The pest index can be used to assist in making decisions about pests that are encountered, whether to ignore them, have zero tolerance for them, or tolerate them up to critical threshold values. Using this approach should enable managers of woody plants in landscapes to effectively limit damage from arthropod pests while minimizing the unnecessary usage of pesticides, thereby fostering the adoption of integrated pest management.