# GTBOP YouTube Description
## Weed Control in Turf — A Review of the Basics and Recent Updates

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Weed Control in Turf: A Review of the Basics and Recent Updates with Dr. Patrick McCullough

Dr. Patrick McCullough, Weed Scientist at the University of Georgia, delivers a comprehensive review of turfgrass weed management covering identification fundamentals, cultural practices, pre-emergent herbicide science, herbicide resistance issues in Georgia, and new products for 2018 including halauxifen-based herbicides from Dow, Vexis, Solero, Dismiss NXT, and the combination product Coastal.

Topics include distinguishing weed species by seed heads, ligules, flowers, and leaf characteristics; the impact of mowing height and irrigation on weed competition; pre-emergent application timing by Georgia region; split application strategies; herbicide resistance mechanisms and management programs for Poa annua and resistant sedges; and detailed profiles of seven new turfgrass herbicide products.

Presented for the GTBOP (Getting the Best of Pests) Green & Commercial Webinar Series
University of Georgia Center for Urban Agriculture
Webinar Date: November 17, 2017
CEU Category: 24 (Ornamental and Turf Pest Control)

🔗 Resources mentioned in this presentation:
• GeorgiaWeather.net — Local soil temperature tracking for application timing
• Color Atlas of Turfgrass Weeds (GCSAA)
• Weeds of Southern Turfgrass (UGA publication)

TIMESTAMPS:
0:00 Introduction
0:46 Weed Identification Books and Resources
2:00 Weed Categories: Grassy, Broadleaf, and Grass-Like
2:43 Identification by Seed Heads
3:57 Comparing Bahiagrass and Dallisgrass
5:13 Poa annua Seed Head Identification
5:34 Using Ligules for Grassy Weed Identification
6:50 Broadleaf Weed Flowers and Day Flower Species
7:52 Leaf Arrangement and Hair Characteristics
9:34 Leaf Markings: White Clover vs. Spotted Burr Clover
10:16 Weed Lifecycles: Winter and Summer Annuals
12:05 Perennial Weeds: Simple and Complex
16:02 Scouting, Early Detection, and Cultural Practices
17:08 Mowing Height Effects on Crabgrass Competition
20:07 Irrigation Influence on Weed Populations
22:05 Seed Quality and Seedlot Contamination
24:07 How Pre-Emergent Herbicides Work
27:00 Pre-Emergent Product Overview and Formulations
29:00 Pre-Emergent Targets and Limitations
29:38 Herbicide Activation: Sprayable vs. Granular
31:07 Spring Application Timing by Georgia Region
32:52 Residual Activity and Product Selection
34:48 Fall Pre-Emergent Timing for Winter Annuals
35:11 Split Applications for Extended Control
36:21 Fall Products for Poa annua Management
37:31 Herbicide Resistance: Overview and Mechanisms
41:01 Poa annua Resistance in Georgia
43:34 Fall Post-Emergent Timing and Sulfonylurea Programs
48:55 Poa annua Control Programs by Turfgrass Species
51:38 Sedge Resistance to Sulfonylureas
53:44 Other Herbicide-Resistant Weed Species
55:01 New for 2018: Halauxifen Products (RELZAR, Game On, Switchblade)
1:01:22 New for 2018: Vexis (Pyrimisulfan + Penoxsulam)
1:05:31 Solero (Mesosulfuron) from Nufarm
1:06:27 Dismiss NXT (Sulfentrazone + Carfentrazone)
1:08:19 Coastal: Three-Way Pre + Post Combination from Sipcam
1:09:53 Conclusion

QUESTIONS ADDRESSED IN THIS PRESENTATION:

Q: What are the key characteristics used to identify grassy and broadleaf weeds?
A: McCullough covers seed heads, ligules, flowers, leaf arrangement, pubescence, and leaf markings, with specific examples including bahiagrass vs. dallisgrass, crabgrass species differentiation, and day flower identification.

Q: How do cultural practices affect weed populations?
A: Research shows raising tall fescue mowing height from 1 to 4 inches reduced crabgrass from 95% to 0% cover. A Florida study found daily irrigation increased dollarweed five- to six-fold compared to as-needed watering.

Q: How do pre-emergent herbicides work?
A: Pre-emergent herbicides bind in the upper soil profile, are absorbed by germinating seedling roots and shoots, and inhibit cell division. They do not prevent germination — seedlings must first emerge and take in the product.

Q: What herbicide resistance issues is Georgia facing?
A: Widespread Poa annua resistance to dinitroaniline pre-emergents and sulfonylurea post-emergents, plus halosulfuron-resistant sedge populations. McCullough recommends combining modes of action for resistance management.

Q: What new herbicide products are coming for 2018?
A: RELZAR, Game On, and Switchblade (halauxifen from Dow); Vexis (pyrimisulfan + penoxsulam); Solero (mesosulfuron from Nufarm); Dismiss NXT (sulfentrazone + carfentrazone from FMC); and Coastal (simazine + imazaquin + prodiamine from Sipcam).

#turfgrass #weedcontrol #pestmanagement #UGA #GTBOP #CEU #lawncare #herbicide #preemergent #poaannua