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# GTBOP Webinar Archive — Extension Agent Resource

## Weed Control in the Landscape & Nursery

### Dr. Mark Czarnota — November 18, 2021

## CEU INFORMATION

Approved Categories:

Category | Description
--- | ---
10 | Private Applicator
21 | Plant Agriculture
22 | Animal Agriculture
23 | Forestry
24 | Ornamental and Turf Pest Control
27 | Right-of-Way Pest Control
31 | Public Health Pest Control
32 | Regulatory Pest Control
35 | Industrial, Institutional, Structural and Health Related

Credit Hours: 1 hour Duration: 50:05 (presentation + Q&A)

## VIEWING INSTRUCTIONS FOR ASYNCHRONOUS CEU DELIVERY

This recorded webinar is approved for continuing education credit in the categories listed above. For county extension agent programs delivering this content asynchronously:

1. Attendees should view the full recording (approximately 50 minutes)
2. The presentation covers weed definitions, physical/biological/chemical control methods, herbicide categories, specific product recommendations, modes of action, and safety — broad applicability across multiple license categories
3. The Q&A section (beginning at 44:54) addresses torpedograss, Virginia buttonweed, and bermudagrass control

## PRESENTATION SUMMARY

Speaker: Dr. Mark Czarnota, Associate Professor of Horticulture (Weed Science), University of Georgia Griffin Campus Moderator: Dr. Shimat Joseph, Turfgrass Entomologist, UGA Griffin Campus Series: Green & Commercial

Dr. Mark Czarnota presents a comprehensive overview of weed control strategies for landscape and nursery professionals. The session covers three primary control approaches — physical removal, physical barriers, and chemical weed control — with the majority of time devoted to herbicide selection and application.

Key content areas include weed identification and life cycle management (annual, biennial, perennial), the distinction between pre-emergent and post-emergent herbicides, selective versus non-selective products, and granular versus sprayable formulations. Czarnota highlights underutilized products including Dimension (dithiopyr) and Marengo (indaziflam), reviews herbicide modes of action, and discusses glyphosate safety research. Biological control methods (grass carp, goats, thistle weevil) and physical barriers (fabrics, mulches) are also covered.

Practical takeaways for applicators: - Maintain a 2–4 inch mulch layer; bare soil always produces weed growth - Apply pre-emergent herbicides in January–February in Georgia; ensure rain within 72 hours - Dimension (dithiopyr) is safe on most turfgrasses and ornamentals and is significantly underutilized - Marengo (indaziflam) provides up to 16 weeks of pre-emergent control on established woody ornamentals - Field applications need 2–4 pre-emergent applications per year; containers need 4–6 - Clethodim (Envoy) is the preferred selective grass herbicide for bermudagrass in ornamentals - Glyphosate or triclopyr can be painted on stumps for selective removal without affecting surrounding plants

## CONTENT TIMESTAMPS

0:00 Introduction and Speaker Background 3:02 What Is a Weed? Definitions and Weediness Predictors 5:13 Challenging Weed Problems in Nursery Production 9:03 Weed Identification and Plant Life Cycles 11:55 Weed Control Methods: Physical Removal and Barriers 15:44 Biological Control: Grass Carp, Goats, Thistle Weevil 19:50 Chemical Weed Control: Impact of Major Herbicides 21:07 Pre-Emergent vs. Post-Emergent Herbicides 25:16 Trade Names, Active Ingredients, and Cost Savings 26:20 Herbicide Modes of Action 29:42 Pre-Emergent Herbicides for Landscape and Nursery 31:17 Post-Emergent and Combination Herbicides 35:16 Recommended Products: Marengo, BroadStar, SureGuard 36:40 Best Practices and Common Application Errors 40:21 Herbicide Fate, Organic Options, and Glyphosate Safety 43:40 Glyphosate Damage, Adjuvants, and Future Technologies 44:54 Q&A: Torpedograss, Virginia Buttonweed, Bermudagrass Control

## ADDITIONAL RESOURCES

- Labels & Safety Data Sheets: CDMS.net
- Turfgrass Weed Control Referral: Dr. Patrick McCullough, UGA

Processed for UGA Center for Urban Agriculture / GTBOP Archives Source: Corrected SRT (Stage 1) — GTBOP_Transcript_2021-11-18_WeedControl.srt (786 blocks)