Webinar: The Latest in Nursery Weed Control
Speaker: Dr. Chris Marble, University of Florida IFAS
Webinar Date: March 12, 2026
Series: Green & Commercial
Exercises: 3
Matching Exercise 1: Pre-Emergent Herbicides and Their Post-Emergence Weed Targets
Timestamp Reference: 10:30 – 12:50
Type: Product-Ingredient / Timing-Practice
Instructions: Match each herbicide or active ingredient in Column A with the weed species it controls or suppresses after emergence, as described by Dr. Marble.
| # | Column A | Column B | |
|---|---|---|---|
| 1 | Dimethenamid-P (Tower, FreeHand) | a) Bittercress up to flowering stage | |
| 2 | Indaziflam (Marengo) | b) Artillery weed | |
| 3 | Isoxaben (Gallery, Gemini) | c) Emerged spurge — stunt or kill | |
| 4 | Oxadiazon (Ronstar G) | d) Small oxalis, stunted spurge, annual bluegrass | |
| 5 | Oxyfluorfen products (OH2, Biathlon) | e) Liverwort on stratified substrates | |
| f) Range of broadleaf species after emergence |
Answer Key:
1 → c, 2 → d, 3 → a, 4 → b, 5 → f
Distractor: e) Liverwort on stratified substrates — liverwort control was achieved through substrate stratification (a non-chemical method), not through any of the herbicides listed.
Source in transcript: Blocks 155–170 (~10:32–11:25)
Matching Exercise 2: Rice Hull Research Findings
Timestamp Reference: 12:50 – 24:20
Type: Timing-Practice
Instructions: Match each rice hull research question in Column A with the finding Dr. Marble reported in Column B.
| # | Column A | Column B | |
|---|---|---|---|
| 1 | Effect of top-dressing fertilizer on two inches of rice hulls | a) About 40% of the applied layer remained | |
| 2 | One inch of rice hulls applied over cotyledon-stage eclipta and Phyllanthus | b) Performed similarly to pre-emergent herbicide rotations for six months | |
| 3 | Weed seeds placed below the rice hull layer | c) 95% or greater reduction in seedling survivability | |
| 4 | Rice hull layer remaining after 12 months outdoors | d) Coleus and Vitex grew significantly less than with incorporated fertilizer | |
| 5 | Rice hull weed control compared to standard herbicide rotations | e) Seeds germinated and emerged normally with no suppression | |
| 6 | Mechanism of rice hull weed control | f) Physical barrier too heavy for seedlings to push through | |
| g) Moisture deprivation — hulls dry rapidly, preventing seed germination on the surface |
Answer Key:
1 → d, 2 → c, 3 → e, 4 → a, 5 → b, 6 → g
Distractor: f) Physical barrier too heavy for seedlings to push through — this describes the mechanism of heavier wood and bark mulches, not rice hulls. Paul Bartley distinguished the two mechanisms during Q&A.
Source in transcript: Blocks 232–350 (~15:24–24:02) for rice hull studies; Blocks 642–659 (~43:29–44:38) for mechanism distinction
Matching Exercise 3: Herbicide Application Equipment Efficiency (LEAP Project)
Timestamp Reference: 31:00 – 37:30
Type: Timing-Practice
Instructions: Match each application method in Column A with the performance data Dr. Marble reported from the LEAP project in Column B.
| # | Column A | Column B | |
|---|---|---|---|
| 1 | Granular application — area covered | a) One employee for six hours | |
| 2 | Granular application — labor required | b) Three minutes | |
| 3 | Granular application — chemical cost | c) 17 acres | |
| 4 | Liquid boom sprayer — area covered | d) $5,500 | |
| 5 | Liquid boom sprayer — labor required | e) 1.3 acres | |
| 6 | Drone granular application — time for half an acre | f) Three employees for five hours | |
| 7 | Drone granular application — application rate | g) 200 pounds per acre | |
| h) 25 gallons per acre |
Answer Key:
1 → e, 2 → f, 3 → d, 4 → c, 5 → a, 6 → b, 7 → g
Distractor: h) 25 gallons per acre — this was the low end of liquid application volumes Marble tested in canopy penetration research, not a drone application rate.
Source in transcript: Blocks 507–531 (~35:16–36:46) for nursery equipment data
Matching Exercise Summary
| Exercise | Topic | Pairs | Distractors | Presentation Section |
|---|---|---|---|---|
| 1 | Pre-emergent post-emergence targets | 5 | 1 | Early (10:30–12:50) |
| 2 | Rice hull research findings | 6 | 1 | Middle (12:50–24:20, plus Q&A) |
| 3 | LEAP project equipment data | 7 | 1 | Late (31:00–37:30) |
Matching exercises produced for UGA Center for Urban Agriculture / GTBOP Moodle Courses
Source: Corrected SRT — GTBOP_Transcript_2026-03-12_NurseryWeedControl.srt (670 blocks)
Archive Package — GTBOP_Archive_Summary_2026-03-12_NurseryWeedControl.md