# GTBOP Moodle Review Activities
## Weed Control in the Landscape & Nursery — Dr. Mark Czarnota (November 18, 2021)

**Source:** Corrected SRT (Stage 1) — GTBOP_Transcript_2021-11-18_WeedControl.srt (786 blocks)
**Structural Reference:** Stage 2 Archive Package — GTBOP_Archive_Summary_2021-11-18_WeedControl.md
**Review Tasks:** 6

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### Review Task 1
**Watch:** 4:23 – 6:40
**Task:** List the six characteristics Dr. Czarnota identifies as predictors of weediness, then describe the specific real-world example he uses for the first characteristic.
**Key Points to Identify:**
- The six characteristics (vegetative reproduction, abundant seed production, rapid establishment, seed dormancy, adaptive traits, disturbed site colonization)
- Yellow and purple nutsedge as the example of vegetative reproductive structures
- Pigweed seed production numbers (5,000–10,000 seeds per plant)

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### Review Task 2
**Watch:** 15:44 – 18:06
**Task:** Identify the four biological control methods Dr. Czarnota describes and note the specific target weed or pest for each. For one method, describe why it was discontinued.
**Key Points to Identify:**
- Grass carp for submerged aquatic weeds (8–10 per surface acre)
- Goats for kudzu (followed by herbicide on regrowth)
- Thistle weevil for musk thistle (larvae prevent seed development over 2–3 years)
- DeVine bioherbicide for strangler vine in citrus (worked too well — eliminated the vine and left no host for the biocontrol agent)

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### Review Task 3
**Watch:** 21:07 – 23:43
**Task:** Explain the key difference between how pre-emergent and post-emergent herbicides work, and identify the critical weather requirement for each type after application.
**Key Points to Identify:**
- Pre-emergent: applied before germination, needs 0.5–1 inch of rain to move into top quarter inch of soil
- Post-emergent: applied after emergence, needs a dry period for leaf absorption
- Glyphosate as the only broad-spectrum systemic (phloem-loaded) post-emergent herbicide

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### Review Task 4
**Watch:** 26:20 – 29:08
**Task:** Describe the modes of action for glyphosate and the dinitroaniline herbicides. For glyphosate, identify the three amino acids affected and explain why this matters for mammalian safety.
**Key Points to Identify:**
- Glyphosate inhibits EPSP synthase, blocking production of tryptophan, phenylalanine, and tyrosine
- The EPSP synthase pathway does not exist in animals — humans obtain these amino acids through diet
- Dinitroanilines disrupt microtubule formation during cell division, preventing chromosome separation
- Visual symptom of dinitroaniline overdose: club rooting

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### Review Task 5
**Watch:** 29:42 – 35:16
**Task:** From the pre-emergent and post-emergent products Dr. Czarnota reviews, identify the two products he recommends most highly for landscape use and note their key advantages and any limitations.
**Key Points to Identify:**
- Dimension (dithiopyr): most underutilized; safe on turfgrasses, broad woody ornamentals, some perennials and annuals
- Marengo (indaziflam): up to 16 weeks control; established woody ornamentals only; does not control nutsedge
- Combination granular products (Snapshot, FreeHand) provide both pre-emergent control and oxyfluorfen burndown

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### Review Task 6
**Watch:** 36:40 – 39:30
**Task:** List the common application errors Dr. Czarnota identifies that reduce herbicide effectiveness, and note his recommended application frequency for field versus container production.
**Key Points to Identify:**
- No rain after pre-emergent application (needs rain within 72 hours)
- Rain immediately after post-emergent application
- Poorly calibrated equipment
- Wrong herbicide for the target weed
- Applying pre-emergent after weeds have already germinated
- Field: 2–4 applications/year; Containers: 4–6 applications/year

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*Generated for UGA Center for Urban Agriculture / GTBOP Moodle Course Activities*
*Source: Corrected SRT (Stage 1) — GTBOP_Transcript_2021-11-18_WeedControl.srt (786 blocks)*
*Structural Reference: Stage 2 Archive Package*