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# GTBOP YouTube Description

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

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