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# GTBOP Webinar — Extension Agent Resource

## Understanding Tree Pests: Disease Interactions, Invasive Threats, and Management Strategies

### Webinar Details

Field | Details
--- | ---
Date | January 15, 2026
Speaker | Dr. Ignazio Graziosi, Assistant Professor, Warnell School of Forestry and Natural Resources, University of Georgia
Moderator | Dr. Bodie Pennisi, UGA Horticulturist
Duration | 52 minutes, 11 seconds
Series | Green & Commercial
CEU Categories | TBD

### CEU Information

Applicable License Categories (pending confirmation): - Category 24 — Ornamental and Turf Pest Control (likely primary) - Category 27 — Right-of-Way Pest Control (possible secondary)

Credit Hours: TBD

Viewing Instructions for Asynchronous CEU Delivery: This archived webinar may be used for self-paced continuing education. Viewers should watch the full presentation (approximately 52 minutes), complete any required assessment activities, and submit documentation per county or program requirements. Sign-in sheets should be submitted to gtbop@uga.edu or mailed to the address printed at the top of the sign-in sheet.

### Content Summary

Dr. Ignazio Graziosi presents a framework for understanding tree pest damage using the disease triangle (pest, host tree, environment) and spiral of tree decline. The presentation is organized around three case studies that cover the major pest-host interaction scenarios landscape professionals encounter:

Case Study 1 — Emerald Ash Borer (EAB): Non-native pest on native trees Covers EAB life cycle and damage identification (water sprouts, D-shaped exit holes, canopy dieback), the role of firewood in spreading the invasion, Georgia's ash species diversity and the white fringetree as an alternate host, the invasion curve concept, importation biological control using specialist parasitoid wasps from Asia, and chemical protection methods (tree injection, bark spray, soil drench). Relevant for agents advising on ash tree conservation and urban forest management.

Case Study 2 — Crapemyrtle Bark Scale (CMBS): Non-native pest on non-native trees Covers CMBS identification (white females, pink eggs, sooty mold), overlapping generations, host range expansion to American beautyberry and St. John's wort, urban heat island effects, chemical control options (soil drench, soil injection, foliar spray — note trunk injection is not effective for crapemyrtle), and the role of lady beetles and green lacewings as predators. Particularly relevant for Georgia agents, as the invasion is still at an early stage in much of the state.

Case Study 3 — Orange-Striped Oakworm Moth: Native pest on native trees Covers life cycle and seasonal timing (late summer/fall, two generations in the South), vulnerability of clonal urban tree plantings with low genetic diversity, natural enemies, and a practical decision framework: 25% defoliation threshold for treatment, and the reduced harm of late-season defoliation. Btk (Bacillus thuringiensis kurstaki) as a selective foliar spray is the recommended first option.

### Key Concepts for Agent Programs

These concepts from the presentation are well-suited for county programming and client consultations:

Disease Triangle — Damage is an interaction of pest, host, and environment. Helps clients understand why the same pest causes different levels of damage in different settings.

Spiral of Tree Decline — Multiple stressor categories (predisposing, inciting, contributing) interact. Soil compaction alone can bring a tree to death. Useful for educating clients on urban tree care beyond pest control.

Invasion Curve — Early detection enables more effective and less costly control. Relevant for CMBS messaging in counties where the pest has not yet established at high levels.

Urban Heat Island Effects — Stresses trees while accelerating insect development. Relevant for any agent working in urban/suburban landscapes.

Aesthetic vs. Actual Damage — The 25% defoliation threshold and seasonal timing consideration help agents advise clients on when treatment is and isn't warranted.

### Suggested Pairings

This webinar complements other GTBOP content covering urban tree care, scale insect management, and integrated pest management principles. It pairs well with presentations on ornamental pest identification, systemic insecticide application, and biological control in landscape settings.

Getting the Best of Pests (GTBOP) | UGA Center for Urban Agriculture For questions about CEU delivery or archived webinar use, contact gtbop@uga.edu