Speaker: Dr. Chris Marble, Associate Professor of Horticulture, University of Florida IFAS, Mid-Florida Research and Education Center, Apopka, FL
Moderator: Dr. Shimat Joseph, University of Georgia
Webinar Date: March 12, 2026
Duration: 45:13
Series: Getting the Best of Pests (GTBOP) — Green & Commercial
CEU Information
Applicable Categories:
| Category | Description | Applicability |
|---|---|---|
| 10 | Private Applicator | Weed management principles applicable to private pesticide applicators in nursery and greenhouse settings |
| 21 | Plant Agriculture | Herbicide application methods, product selection, and rotation strategies for plant production |
| 24 | Ornamental and Turf Pest Control | Direct focus — weed management in container nursery and greenhouse ornamental production |
| 27 | Right-of-Way Pest Control | Bare-ground herbicide options (StrataCor, SureGuard Extra) and application equipment comparisons |
| 32 | Regulatory Pest Control | Herbicide label compliance, mode of action rotation to delay resistance, labeled-use tables |
Primary audience: Category 24 holders working in nursery production, greenhouse operations, or landscape installation sourcing from nurseries.
Viewing Instructions for Asynchronous CEU Delivery
This 45-minute webinar covers three areas of applied nursery weed management research and is suitable for individual or group asynchronous viewing.
Suggested viewing structure:
- Part 1 (0:00–12:50): Non-chemical control — hand weeding frequency study results and early post-emergence activity of pre-emergent herbicides. Runs about 13 minutes.
- Part 2 (12:50–27:20): Rice hull mulch and substrate stratification research — fertilizer placement, emerged seedling suppression, outdoor degradation, and liverwort control. Runs about 14 minutes.
- Part 3 (27:20–39:00): Herbicide rotation development, new bare-ground products, and LEAP project equipment efficiency data. Runs about 12 minutes.
- Q&A (40:00–45:13): Substrate stratification temperature effects and rice hull vs. wood mulch mechanisms.
Content Summary
Dr. Chris Marble presented applied research from his UF IFAS nursery weed management program. The presentation covers three topic areas useful for professionals managing weeds in container nurseries, greenhouses, or landscape production.
Hand weeding frequency: A multi-site study (Florida, North Carolina, Virginia) found that weeding every two weeks instead of every eight — pulling only large weeds likely to seed, leaving cotyledon-stage seedlings — reduced weeding costs by 40–60%. The Florida site achieved 65% savings. The approach works as a cleanup protocol for heavily infested blocks.
Rice hull mulch: One inch of rice hulls killed 95%+ of small emerged seedlings (eclipta, Phyllanthus, bittercress, oxalis). Top-dressing fertilizer on two inches of hulls reduced ornamental growth — incorporate fertilizer below the hull layer instead. Outdoors, 40% of the applied layer remained after 12 months; hulls matched pre-emergent herbicide rotations for six months before degradation reduced control. Mechanism is moisture deprivation, not physical barrier.
Substrate stratification: Coarser bark on top with fertilizer placed below eliminated liverwort for 20+ weeks and reduced bittercress by 40–60%.
Herbicide rotation: Marble demonstrated using the 2017 Southeast Pest Management Guide to build site-specific rotations by season, weed species, and mode of action group. Two new bare-ground products: StrataCor (pethoxamid, SePRO) and SureGuard Extra (flumioxazin + pyroxasulfone).
LEAP project equipment data: Liquid boom sprayer covered 17 acres with one employee in six hours at half the chemical cost of a three-person granular crew covering 1.3 acres in five hours. Drone application covered a half acre in three minutes.
Discussion Points for County Programs
- How does hand weeding frequency compare to current practices at local nurseries? The 40–60% cost savings figure gives agents a concrete data point for grower conversations.
- Rice hulls are practical for short-term crops (six to eight months) where herbicide-sensitive ornamentals limit chemical options. Pine bark mulch better suits longer production cycles.
- The LEAP project equipment efficiency data may interest growers considering capital investments in boom sprayers or drone technology. Marble is actively seeking collaborator nurseries.
- Substrate stratification for liverwort control requires no chemical input — a strong fit for operations seeking non-chemical IPM options.
Additional Resources
- Publication: “Frequent Hand Weeding Saves Money” — Barker and Neal, 2016
- 2017 Southeast Pest Management Guide (herbicide-by-ornamental species tables)
- UF IFAS Weed Management Training Course — four weeks, eight lessons, English and Spanish
- LEAP Project — contact Dr. Marble for collaboration (search “Chris Marble UF IFAS”)
Prepared for UGA Cooperative Extension / GTBOP Archives — Asynchronous CEU Resource
Source: GTBOP_Archive_Summary_2026-03-12_NurseryWeedControl.md