Speakers: Dr. Benjamin Pritchard, Assistant Professor of Turfgrass Weed Science, UGA Griffin Campus; Dr. Clint Waltz, Turfgrass Extension Specialist, UGA Griffin Campus
Webinar Date: November 13, 2025
Moderator: Dr. Shimat Joseph, UGA Extension Entomologist
Duration: 57:20
NARRATIVE SUMMARY
This special industry update webinar featured two leading UGA turfgrass specialists sharing critical insights for the 2025 season. Dr. Benjamin Pritchard, who joined UGA in July 2025, introduced himself to the Georgia turfgrass industry and shared observations from his first four months in the position. His presentation focused on key weed management challenges and emerging research priorities, including the widespread issue of turfgrass versus turfgrass competition, particularly bermudagrass encroachment into zoysiagrass and centipedegrass stands. Dr. Pritchard highlighted the unusual prevalence of prostrate spurge (Euphorbia maculata) during the 2025 season, noting that control difficulties were observed nationwide in areas experiencing wet spring conditions followed by hot, dry periods. He presented new herbicide tolerance research on zoysiagrass cultivars, demonstrating that many newer varieties show improved tolerance to broadleaf herbicides compared to older cultivars. His discussion of Poa annua (Poa annua) management emphasized the critical importance of pre-emergent timing, with soil temperature data from Blairsville, Griffin, and Tifton indicating that the largest germination flush occurs when seven-day average soil temperatures reach 66°F. Dr. Pritchard outlined his extension-focused program vision and encouraged industry professionals to complete his turfgrass weed needs assessment survey.
Dr. Clint Waltz provided comprehensive environmental data analysis from the Griffin campus weather station, reviewing temperature and rainfall patterns from 2025 and their implications for turfgrass management. He introduced Trofinity, a newly EPA-labeled nematicide from Syngenta that represents a significant advancement for residential lawn treatment, as it carries a homeowner lawn use label. Dr. Waltz emphasized its effectiveness on endoparasitic nematodes including root knot, lance, and sting nematodes, with 8-12 month persistence and no turfgrass phytotoxicity. His disease management discussion addressed the active large patch pressure on zoysiagrass, St. Augustinegrass, and centipedegrass, explaining that grasses infected during fall dormancy will exhibit delayed spring green-up. He clarified critical concepts about fungicide expectations, distinguishing between curative and preventative applications and emphasizing that fungicides provide 14-28 days of residual activity rather than permanent control. Dr. Waltz reviewed fertilization timing for warm-season grasses, advising against nitrogen applications during dormancy and recommending soil temperatures of 65°F and rising before spring fertilization. Both specialists emphasized their commitment to applied research directly supporting Georgia’s turfgrass professionals and concluded with an extensive question-and-answer session.
YOUTUBE TIMESTAMPS
0:00 Introduction and Webinar Overview
1:40 Dr. Benjamin Pritchard Introduction and Background
2:25 Educational Background: University of Tennessee
3:38 Master’s Research: Indaziflam Resistance Screening
4:35 PhD Research: Novel Herbicide Tetflupyrolimet
5:28 First Observations in Georgia: Common Questions
6:12 Prostrate Spurge Challenges in 2024
7:25 Zoysiagrass Herbicide Tolerance Research
9:36 Understanding the Weed Control Cycle
10:42 Poa annua: Annual Bluegrass Management
11:05 Seasonal Emergence Research and Soil Temperatures
12:00 Pre-emergent Application Timing for Georgia
13:30 Zone Defense Strategy for Weed Management
15:07 Program Vision: Extension and Research Integration
16:58 Turfgrass Weed Needs Assessment Survey
18:25 Q&A: Dallisgrass Control Options
19:28 Q&A: Atrazine for Early Post-Emergence Control
21:10 Dr. Clint Waltz Introduction
23:01 Environmental Conditions: 2024 Climate Review
24:00 Air Temperature Analysis: Griffin Campus Data
26:00 Soil Temperature Trends and Implications
27:40 Rainfall Patterns and Turfgrass Response
30:30 Color Retention in Warm-Season Grasses
33:05 NEW PRODUCT: Trofinity Nematicide Introduction
34:15 Trofinity Label and Site Uses
35:20 Effectiveness on Endoparasitic Nematodes
37:14 Brown Patch and Large Patch Disease Observations
39:55 Fungicide Principles: What They Do and Don’t Do
40:40 Curative vs. Preventative Applications
42:00 Homeowner Fungicide Products: Disease EX Review
44:00 Azoxystrobin Products and Application Timing
45:30 Propiconazole Products and Residual Activity
47:20 Fall Fertilization: Warm-Season Grass Recommendations
49:17 Mowing Height Guidance for Dormancy Period
50:02 Upcoming Programs and Field Day Announcement
50:27 Q&A: Mulching Leaves and Disease Development
51:17 Q&A: Winter Irrigation Frequency
52:03 Q&A: Combining Fungicides for Resistance Management
53:09 Q&A: Corn Fertilizer for Winter Application
54:05 Q&A: Biosolid Fertilizer Timing
55:20 Q&A: Bermudagrass Mowing Height Adjustment
56:25 Q&A: Sand-Based Sports Field Publications
57:12 Closing Remarks and Thank You
QUESTIONS & ANSWERS
Q: What are the best control options for dallisgrass in turfgrass?
A: Sulfonylurea herbicides provide good selective control in many situations. However, one of the most cost-effective and reliable options remains spot treatment with non-selective herbicides like glyphosate or glufosinate applied with a wipe-on applicator, especially for problematic patches. This approach allows application flexibility regardless of season and minimizes turfgrass injury.
Q: Is atrazine effective as a post-emergent herbicide for Poa annua in the fall?
A: Atrazine does provide some early post-emergence activity on Poa annua, but relying on a single active ingredient is not recommended. Tank-mixing atrazine with another herbicide like mesotrione (Tenacity) provides broader spectrum control and reduces the risk of developing herbicide resistance. Given how widespread resistance is in annual bluegrass populations, using multiple modes of action is critical to preserve control options.
Q: When should pre-emergent herbicides be applied for Poa annua control in Georgia?
A: Research shows the largest Poa annua germination flush occurs when seven-day average soil temperatures reach 66°F combined with a half-inch of rainfall. In 2024, this occurred on October 20th in Blairsville, October 25th in Griffin, and October 31st in Tifton. Pre-emergent applications should be made before these dates—ideally late September to early October—to establish residual activity before peak germination begins.
Q: How does the new nematicide Trofinity differ from existing products?
A: Trofinity is significant because it carries a residential lawn site use label, which has historically been difficult to obtain for nematicides. It is highly effective on endoparasitic nematodes including root knot, lance, and sting nematodes. The product is an SDHI chemistry with 8-12 month persistence, slow soil movement that keeps it in the root zone, no turfgrass phytotoxicity, and low mammalian toxicity. It received EPA approval in late 2024 and should be commercially available for the 2025 season.
Q: If large patch is visible on zoysiagrass or St. Augustinegrass in fall, what are the implications for spring?
A: Grasses affected by large patch in fall will not improve during dormancy. The disease damage means those areas will be slower to green up in spring compared to healthy turf. While the disease may not be actively spreading during winter, the infection that occurred in fall has already impacted plant health, resulting in delayed spring recovery in affected patches.
Q: What is the difference between curative and preventative fungicide applications?
A: Curative or “arresting” applications are made when disease is already active to stop it from spreading further. Preventative or prophylactic applications are made before disease conditions become favorable to protect plants from infection. For warm-season grasses with a history of large patch, preventative applications in September-October can be valuable. Regardless of approach, fungicides provide 14-28 days of residual activity and are not “one-and-done” products—multiple applications are typically needed during disease-favorable conditions.
Q: Should warm-season grasses receive nitrogen fertilizer in November?
A: No, nitrogen fertilization is not recommended for dormant warm-season grasses. The grass cannot actively use the nitrogen, and organic sources like biosolids require microbial activity to convert nitrogen to plant-available forms. With cooling soil temperatures, this microbial breakdown essentially ceases. Applications made in November will not benefit the turf until soil temperatures rise in mid-to-late spring. Instead, wait until March when soil temperatures reach 65°F and rising at the four-inch depth before applying nitrogen.
Q: What mowing heights should be maintained for warm-season grasses going into dormancy?
A: Maintain current heights rather than adjusting now. St. Augustinegrass should stay at 3-4 inches, centipedegrass at 1.5-2 inches, and bermudagrass and zoysiagrass at 1-1.5 inches. Lowering mowing height in fall opens the canopy and allows light penetration that promotes winter annual weed germination. Height adjustments for bermudagrass grown too tall should be made gradually in spring using a stair-step approach—lowering the height incrementally over 6-8 weeks as the grass actively grows.
Q: Does mulching tree leaves in fall increase turfgrass disease development?
A: Mulching leaves is unlikely to increase disease. In fact, chopping leaves into smaller pieces allows them to fall into the canopy more easily, where soil microbes can break them down. This improves air circulation around turfgrass leaves, which helps them dry out and actually reduces disease potential compared to leaving thick mats of whole leaves on the lawn.
Q: How frequently should irrigation be applied during winter months in coastal Georgia?
A: Once warm-season grasses are fully dormant, irrigation needs are minimal. Winter is typically Georgia’s wetter period, and natural rainfall is generally sufficient. If an unusually dry period occurs in late winter (February-April), applying a half-inch of irrigation every two weeks would be beneficial. However, routine supplemental irrigation is not necessary during normal winter conditions for dormant turfgrass.
Q: Should azoxystrobin (SDHI) and propiconazole (DMI) fungicides be combined or used separately?
A: Some professional-grade products contain both active ingredients pre-mixed. For homeowners and many commercial applications, alternating these products rather than combining them is preferred to reduce fungicide resistance risk. Continually using the same combination exposes the pathogen population to repeated selection pressure. Golf courses and sports fields may have more flexibility to combine products because they can rotate in additional fungicide groups to break the selection cycle.
Q: Are there recent UGA publications on managing sand-based sports fields?
A: The most comprehensive resource is “Designing, Constructing, and Maintaining Bermudagrass Sports Fields,” a publication developed with colleagues from Clemson and University of Florida. While the publication is 15-20 years old, it remains one of the best and most cost-effective resources available, covering design, construction, and maintenance including sand-based systems. It is available as a hard copy through the University of Georgia for $15-20, with approximately 80-90 copies still in stock.
ADDITIONAL RESOURCES
Dr. Benjamin Pritchard Contact:
Email: benjamin.pritchard@uga.edu
Follow on X (Twitter) and LinkedIn for research updates
Turfgrass Weed Needs Assessment Survey:
Available through Dr. Pritchard’s contacts and extension channels
UGA Turf Team Publications:
- Circular 1088: Large Patch and Brown Patch Management (Dr. Alfredo Martinez)
- Bermudagrass Sports Fields Design and Maintenance (available through UGA Extension)
Upcoming Events:
- Coastal Landscape Pro University – Savannah, GA – December 4, 2025
- Landscape Pro Atlanta – January 28, 2026
- UGA Turfgrass Research Field Day – Griffin, GA – August 5, 2026
Weather Data:
Georgia Automated Environmental Monitoring Network: www.georgiaweather.net
For questions about turfgrass weed science, contact Dr. Benjamin Pritchard. For questions about turfgrass management, contact Dr. Clint Waltz. All specialists are based at the University of Georgia Griffin Campus.