# GTBOP Webinar Archive — Extension Agent Resource
## Weed Control in the Landscape & Nursery
### Dr. Mark Czarnota — November 18, 2021

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## 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)

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## 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

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## 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

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## 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

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## ADDITIONAL RESOURCES

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

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