Exploring Novel Adjuvants and Herbicide Synergies: Pyridate and Ethoxylated Lecithin for Improved Control of Turfgrass Weeds

Maintaining healthy, weed-free lawns, golf courses, and sports fields is tougher than ever due to weeds that resist common herbicides, unpredictable weather, and stricter environmental rules. This dissertation explores two promising tools to tackle these challenges: pyridate, a herbicide used in farming since the 1980s, and ethoxylated lecithin (EL), a new eco-friendly additive made from soybeans. Through four studies, we tested how these tools can control troublesome weeds—false green kyllinga, yellow nutsedge, herbicide-resistant annual bluegrass, and smooth crabgrass—while keeping grass safe and vibrant. The first study checked if pyridate harms seven types of turfgrass, like bermudagrass and Kentucky bluegrass. The second examined how well pyridate controls kyllinga and nutsedge in lawns. The third looked at combining pyridate and ALB-2025, an experimental adjuvant, with another herbicide, glufosinate, to fight resistant annual bluegrass. The fourth tested whether EL improves quinclorac, a crabgrass killer, especially when rain washes herbicides away. From 2022 to 2024, we ran experiments in the field and greenhouses, applying treatments with sprayers and checking results over weeks or months by measuring grass health and weed control, and using special tools to measure chemical movement. We found pyridate is safe for most turfgrass at lower doses, causing only temporary damage at higher doses or when mixed with another herbicide, particularly in warm, wet conditions. It controlled kyllinga and nutsedge as well as or better than standard treatments, clearing up to 98% of weeds when paired with another chemical. For resistant annual bluegrass, pyridate and ALB-2025 improved glufosinate activity, reducing weeds by 95–97% even months later, by helping the herbicide absorb into plants faster. EL also boosted quinclorac's crabgrass control to 91%, even after rain, compared to 75% with typical additives or 63% when applied alone. These results show pyridate , ALB-2025, and EL can help keep lawns and fields weedfree, even against tough, resistant weeds, while being kinder to the environment. By offering new ways to use herbicides smarter, this work supports greener, healthier turfgrass for communities, sports, and recreation, despite growing challenges. Future efforts should fine-tune these tools to make them even more effective for everyone managing grass.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Plant Pathology, Physiology and Weed Science

Department dc:contributor.department

Plant Pathology, Physiology and Weed Science

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2025

Author dc:creator

• Corbett, Bret

Chair dc:contributor.committeechair

• Askew, Shawn D.

Committee members dc:contributor.committeemember

• Yanes, Jaime
• McCall, David S.
• Goatley, J. Michael Jr.

• Novel adjuvants
• Pyridate
• Ethoxylated lecithin
• weed control
• herbicide efficacy
• L-Glufosinate
• Annual Bluegrass (Poa annua)
• Photosynthesis inhibition
• Sedge (Cyperus spp.)
• Green Kyllinga (Kyllinga brevifolia) smooth crabgrass
• Digitaria ischaemu

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

vt_gsexam:43693

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/133535