# GTBOP Webinar Archives — Review Prompts
Getting the Best of Pests — Processed webinar archives for the UGA Center for Urban Agriculture

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# 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

### 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)

### 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)

### 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

### 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

### 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

### 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

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