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# GTBOP Moodle Matching Exercises

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

Webinar Date: July 13, 2023 Speaker: Dr. Chris Marble, University of Florida Series: Green & Commercial Source Documents: Corrected SRT (618 blocks) + Archive Package (Stage 2)

### Matching Exercise 1: Post-Emergence Herbicide Products and Characteristics

Timestamp Reference: 37:01 – 42:22 (primary coverage area) Type: Product-Characteristic

Instructions: Match each herbicide or herbicide type in Column A with its correct characteristic described by Dr. Marble in Column B. Two items in Column B are distractors and will not be matched.

# | Column A |  | Column B
--- | --- | --- | ---
1 | Glyphosate (Ranger) |  | a) Primarily contact-acting; broad-spectrum on broadleaves, grasses, and sedges
2 | Glufosinate (Finale/Cheetah) |  | b) Systemic post-emergence herbicide; most common standard for spot spraying in landscape beds
3 | Diquat (Reward) |  | c) Effective on Asteraceae family weeds and legumes; can be used in planting beds
4 | Acetic acid products |  | d) Required the most follow-up applications in Dr. Marble's comparison study due to weaker initial control
5 | Desiccant-type alternatives (Axxe, Finalsan, FireWorxx) |  | e) Pre-emergent herbicide applied to gravel production areas in nurseries
6 | Lontrel (clopyralid) |  | f) Provided 60–90% burndown at two weeks but control dropped dramatically by four to eight weeks as weeds recovered
7 | Graminicides (Segment, Envoy, Fusilade, Acclaim) |  | g) Work fast as desiccants with visible symptoms within 30 minutes; some are OMRI-certified for organic use
|  |  | h) Affect only true grasses; can be applied over the top of hundreds of broadleaf ornamental species
|  |  | i) Systemic herbicide that provides both pre- and post-emergence activity on bittercress

Answer Key: 1 → b, 2 → a, 3 → d, 4 → f, 5 → g, 6 → c, 7 → h

Distractors: e (describes Marengo, discussed in Q&A), i (describes Gallery/isoxaben characteristics)

Source in transcript: Blocks 447–531, ~37:01–43:50; Block 352 for Reward/diquat performance

### Matching Exercise 2: Pre-Emergence Herbicide Mode of Action Groups

Timestamp Reference: 19:17 – 22:45 (primary coverage area) Type: Product-Category

Instructions: Match each pre-emergent herbicide product or active ingredient in Column A with its correct mode of action group as discussed by Dr. Marble in Column B. One item in Column B is a distractor and will not be matched.

# | Column A |  | Column B
--- | --- | --- | ---
1 | Gallery (isoxaben) |  | a) Group 14 — PPO inhibitor
2 | Indaziflam (Specticle/Marengo) |  | b) Group 3 — Mitosis inhibitor
3 | SureGuard (flumioxazin) |  | c) Group 29 — Cellulose biosynthesis inhibitor
4 | FreeHand |  | d) Group 21 — used in combination products with isoxaben
5 | Snapshot |  | e) Group 15 — Very long chain fatty acid inhibitor
6 | Prodiamine/dithiopyr (Group 3 herbicides) |  | f) Group 3 + 14 combination product
|  |  | g) Group 3 + 21 combination product

Answer Key: 1 → d, 2 → c, 3 → a, 4 → f, 5 → g, 6 → b

Distractor: e (VLCFA inhibitor group — mentioned as Group 15 in the rotation chart but not matched to a specific product in this exercise)

Notes: Dr. Marble color-coded his pre-emergence options chart by mode of action and explained that combination products contain two different herbicide groups. He specifically discussed Group 3 (mitosis inhibitors, represented by yellow) and Group 14 (PPO inhibitors, represented by orange) as the most common groups in ornamental herbicides. Indaziflam was identified as the sole Group 29 representative. The isoxaben combination products were identified as Group 21 plus 3 combinations.

Source in transcript: Blocks 225–268, ~19:17–22:46; Blocks 606–607 for Marengo/Specticle/indaziflam equivalency

### Matching Exercise 3: Weed Management Timing and Practice

Timestamp Reference: 6:35 – 8:07 and 31:55 – 35:19 (primary coverage areas) Type: Timing-Practice

Instructions: Match each weed management scenario in Column A with the recommended timing or practice described by Dr. Marble in Column B. Two items in Column B are distractors and will not be matched.

# | Column A |  | Column B
--- | --- | --- | ---
1 | Pre-emergent reapplication interval in nursery container production |  | a) February to March in the Southeast
2 | Pre-emergent reapplication interval in landscape beds |  | b) Apply when weeds are small and actively growing, before they flower and set seed
3 | If only making one pre-emergent application per year in the landscape |  | c) Every 8 to 12 weeks
4 | Fall pre-emergent application timing in the landscape |  | d) Two to three applications per year
5 | Optimal timing for post-emergence herbicide applications |  | e) August to October, before cool-season weeds like chickweed and annual bluegrass germinate
6 | When targeting doveweed with a second landscape application |  | f) Apply when weeds are large and stressed for maximum herbicide uptake
7 | Best time of day for post-emergence applications |  | g) May to June, timed for this later-germinating warm-season species
8 | Avoiding injury from over-the-top pre-emergent applications |  | h) Early morning on a clear, sunny day
|  |  | i) Apply during periods of active new growth for maximum absorption
|  |  | j) Avoid periods of tender new growth, bud swell, and high temperatures

Answer Key: 1 → c, 2 → d, 3 → a, 4 → e, 5 → b, 6 → g, 7 → h, 8 → j

Distractors: f (opposite of what Marble recommended — stressed weeds are harder to control), i (opposite of the injury-avoidance guidance — new growth increases susceptibility)

Source in transcript: Blocks 85–99 (~6:35–8:07) for nursery/landscape intervals; Blocks 104–112 (~8:20–9:11) for injury avoidance; Blocks 136–148 (~11:30–12:43) for post-emergence timing and time of day; Blocks 370–421 (~31:55–35:02) for landscape timing examples; Block 411 (~34:34) for doveweed timing

## Matching Exercises Summary

Exercise | Type | Pairs | Distractors | Transcript Coverage
--- | --- | --- | --- | ---
1 | Product-Characteristic | 7 | 2 | 37:01–43:50
2 | Product-Category (MOA) | 6 | 1 | 19:17–22:46
3 | Timing-Practice | 8 | 2 | 6:35–8:07, 31:55–35:19

Source document: Corrected SRT — GTBOP_Transcript_2023-07-13_WeedControlOrnamentals.srt (618 blocks)

Generated for UGA Center for Urban Agriculture / GTBOP Moodle Certificate Courses