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# GTBOP YouTube Description

## Weed Control in Ornamentals for the Nursery and Landscape — Dr. Chris Marble

Dr. Chris Marble, Associate Professor at the University of Florida's Mid-Florida Research and Education Center, presents a comprehensive guide to developing herbicide programs for nursery and landscape ornamentals. He covers why herbicides fail (poor calibration is the #1 cause), proper timing for pre-emergent and post-emergence applications, and a three-step process for selecting and rotating herbicides by mode of action. Using container-grown gardenia as an example, Marble walks through the 2017 Southeast Pest Control Guide to build a year-round rotation targeting primary and secondary weed species. Research from his program shows that combining pre-emergent herbicides with post-emergence treatments reduces total herbicide use by 40–60% and costs by up to 30%. He also reviews glyphosate alternatives including glufosinate and desiccant-type products, plus underutilized selective options like graminicides for grass control in ornamental beds.

🔗 UF Mid-Florida REC — Dr. Marble's faculty page with free calibration calculators, weed ID tools, and publications 🔗 2017 Southeast Pest Control Guide — Free download with herbicide efficacy and ornamental safety charts

Presented as part of the Getting the Best of Pests (GTBOP) Green & Commercial Webinar Series, hosted by the UGA Center for Urban Agriculture.

📋 CEU Categories: 10 (Private), 21, 23, 24, 27, 31, 32, 35 ⏱️ Duration: 50:38

— TIMESTAMPS —

0:00 Introduction and Speaker Credentials 0:58 Overview: Weed Control in Nurseries and Landscapes 1:36 Why Herbicides Fail: Calibration and Application 4:34 Calibration Tools and Mixing Calculators 6:35 Pre-emergent Herbicide Timing 8:20 Avoiding Plant Injury During Application 9:29 SureGuard Holly Trial: New Growth vs. Hardened Foliage 10:42 Post-emergence Herbicide Timing 11:30 Environmental Factors Affecting Efficacy 13:18 Stressed Weeds and Mowing Impacts 14:28 Ranking Factors That Impact Post-emergence Performance 15:38 Importance of Developing a Program, Not Just Products 17:17 Herbicide Rotation and Resistance Prevention 18:48 Three Steps to Choosing Herbicides 19:17 Pre-emergence Options Color-Coded by Mode of Action 20:48 The 2017 Southeast Pest Control Guide 21:00 Step 1 Example: Labeled Options for Container-Grown Gardenia 22:02 Grouping Herbicides by Mode of Action 23:01 Step 2: Targeting Primary and Secondary Weed Species 25:20 Step 3: Building a Year-Round Rotation 27:03 Year-Round Nursery Rotation Plan by Month 27:34 Research: Pre-emergent + Post-emergent vs. Post-Only Programs 30:44 Cost Savings and Herbicide Reduction Results 31:55 Application Interval Considerations 32:09 Landscape-Specific Rotation Planning 33:52 Timing Examples: One, Two, or Three Applications Per Year 35:20 Generic Landscape Rotation Example by Season 37:01 Post-emergence Alternatives to Glyphosate in Landscape Beds 38:08 Glufosinate (Finale/Cheetah) as an Alternative 38:43 Non-Selective Alternatives: Desiccant-Type Herbicides 40:12 Acetic Acid Trial: Burndown and Recovery Results 42:23 Selective Post-emergence Options for Landscape Beds 43:04 Graminicides: Underutilized Grass-Selective Herbicides 43:55 Basagran, Lontrel, Certainty, and Scepter 44:44 UF Mid-Florida REC Resources and Contact Information 45:52 Q&A: Signal Words and PPE Requirements 48:02 Q&A: Wind Drift and Reducing Spray Drift 49:08 Q&A: Marengo for Nursery Gravel Areas

— Q&A HIGHLIGHTS —

Q: What is the #1 reason herbicides fail? A: Poor calibration. Dr. Marble's field measurements found some applicators off by 50–several hundred percent of target rate. UF offers free calibration calculators for both granular and liquid applications.

Q: How should professionals select pre-emergent herbicides for a specific crop? A: Three steps — (1) determine what's labeled/safe for the ornamental, (2) identify primary and secondary weed species by season, (3) match herbicides rated "good" on primary species and "fair+" on secondary, then rotate modes of action across the year.

Q: How much does adding pre-emergent herbicides reduce overall use and cost? A: UF research showed combining Specticle or SureGuard with post-emergence treatments reduced total herbicide active ingredient by 40–60% and costs by 3–30% over 12 months, with far fewer follow-up applications needed.

Q: What are the main alternatives to glyphosate in landscape beds? A: Glufosinate (Finale/Cheetah) is the most common. Desiccant-type products like Axxe, Finalsan, and FireWorxx provide fast burndown but usually require follow-up applications. Selective graminicides (Segment, Envoy, Fusilade, Acclaim) are underutilized options safe on hundreds of broadleaf ornamentals.

# GTBOP #WeedControl #Ornamentals #Herbicides #PestManagement #UGA #CEU #LandscapeManagement #NurseryProduction