About

Travis Gannon is a Professor in the Department of Crop and Soil Sciences at NC State University, located in Williams Hall. His research focuses on pesticide fate and behavior, with specific interests in chemical control strategies for Poa annua in managed turfgrass systems, herbicide impacts on crops such as corn, cotton, soybean, and tobacco, and the distribution and resistance of herbicides like paraquat in North Carolina. Gannon's work also includes studying cover crops, fall residual herbicides, and the movement of herbicides in turfgrass and roadside environments. His contributions aim to improve understanding of herbicide efficacy, environmental impact, and resistance management in agricultural and turfgrass systems.

Research topics

• Biology
• Horticulture
• Agronomy
• Ecology
• Chemistry
• Biochemistry
• Environmental science
• Botany
• Geology
• Toxicology
• Animal science
• Geotechnical engineering
• Soil science

Selected publications

• Soybean and tobacco response to sublethal rates of herbicides used along roadsides

  Crop Forage & Turfgrass Management · 2026-02-23

  articleOpen access

  Abstract Herbicides are one of the primary tools for vegetation management along roadsides. However, the drift of particles and vapors from herbicide applications along roadsides can cause damage and yield loss in adjacent sensitive crops. The objective of this research was to investigate the response of soybean [ Glycine max (L.) Merr.] and tobacco ( Nicotiana tabacum L.) to sublethal rates of five herbicides [sulfometuron‐methyl, indaziflam, triclopyr, triclopyr + clopyralid, and 2,4‐dichlorophenoxyacetic acid (2,4‐D) + dichlorprop] commonly used along North Carolina roadsides. Each herbicide was applied at four rates (0.01×, 0.05×, 0.10×, and 1× of the field rate) and at six different timings (18, 12, and 6 weeks before planting or transplanting, at planting or transplanting, and 4 and 8 weeks after planting or transplanting). Field studies were conducted at the Sandhills Research Station near Jackson Springs, NC, in 2022 and 2023. In soybean, triclopyr applied post‐planting caused the greatest injury and yield loss, up to 100% when applied at the full dose (1×), while indaziflam was most damaging at or before planting. In tobacco, triclopyr followed by 2,4‐D + dichlorprop applied post‐transplanting caused the greatest injury and height reduction, whereas indaziflam caused mild visual injury (≤28%) and minimal height reduction across all timings. Crop damage generally increased with rate; however, injury, height reduction, and yield loss were occasionally observed even at the lowest rate (0.01×). These findings demonstrate that herbicides commonly used for roadside vegetation management differ in their potential to injure soybean and tobacco crops, underscoring the importance of informed and cautious herbicide selection to minimize the risk of off‐target injury when these crops are grown near roadsides.

  PublisherDOI

• Impact of sub‐lethal rates of herbicides commonly used in roadside vegetation management on corn and cotton

  Agronomy Journal · 2026-01-01

  articleOpen access

  Abstract Herbicide spray drift from roadside application sites poses risks of damaging nearby sensitive crops. The objective of this research was to investigate the impact of five herbicides (sulfometuron‐methyl, indaziflam, triclopyr, triclopyr + clopyralid, and 2, 4‐D + dichlorprop) commonly used to manage roadside vegetation at four application rates (0.01x. 0.05x, 0.1x, and 1x of the field rate) and six application timings (18, 12, and 6 weeks before planting, at planting, and 4 and 8 weeks after planting) on corn ( Zea mays L.) and cotton ( Gossypium hirsutum L.). Field studies were conducted at Upper Coastal Plain Research Station in Rocky Mount, NC, in 2022 and 2023. Although herbicide sensitivity varied by crop species, both species presented higher levels of injury and stunting for application conducted at planting and early post‐planting, and at higher rates. In corn, sulfometuron‐methyl caused the greatest damage. When applied at 4 weeks after planting, this herbicides caused injury of 100% and 48%, and height reduction of 66% and 16%, at 0.1x and 0.01x rates, respectively. In cotton, synthetic auxin herbicides, particularly 2, 4‐D + dichlorprop and triclopyr, were the most damaging post‐emergence. For instance, 2, 4‐D + dichlorprop applied 4 weeks after planting at the 0.01× rate caused 78% injury and 25% height reduction. This study highlights the importance of herbicide selection and application timing when spraying along roadsides to minimize the risk of spray drift damaging nearby corn and cotton fields.

  PublisherOA PDFDOI

• Chemical control strategies for <i>Poa annua</i> in managed turfgrass systems

  Crop Forage & Turfgrass Management · 2026-02-10

  articleOpen access

  Abstract Poa annua L. is a widespread and persistent weed in managed turfgrass systems, exhibiting both annual and short‐lived perennial growth habits. Effective management requires an integrated approach, with chemical herbicides remaining a primary tool. This review outlines the current landscape of chemical control strategies, including pre‐emergence and post‐emergence herbicide options, plant growth regulators, and emerging chemistries. Herbicide resistance in Poa annua continues to pose a significant challenge, with confirmed cases spanning multiple modes of action. Consequently, sustainable management depends on rotating herbicide classes, using mixtures and sequences of treatments, and integrating nonchemical tactics. Continued research into novel herbicide modes of action, application technologies, and integrated weed management approaches will be critical for maintaining long‐term control of Poa annua across diverse turfgrass systems.

  PublisherDOI

• Impact of Fungicide Applications on Sweetpotato Roots and Slips for Managing Black Rot Disease ( <i>Ceratocystis fimbriata</i> ) and Their Effect on Pesticide Residue Levels

  Plant Disease · 2025-09-23 · 2 citations

  article

  , the causal agent of black rot, remains a major concern for sweetpotato producers and is commonly managed through the application of fungicides. As a result of the European Union's (EU) restricted residue tolerances for import products treated with pesticides, the use of fungicides for management of sweetpotato diseases is limited. Identifying fungicides and application practices that ensure disease-free sweetpotatoes while meeting export residue requirements is critical for effective disease management and export marketability. Field experiments were executed in 2022 and 2023 to quantify residue values of three active ingredients (thiabendazole, azoxystrobin, and difenoconazole) when applied at either bedding, transplant, or both bedding and transplant when managing sweetpotato black rot. Root and vine samples were collected at harvest to analyze the detectable residue levels of the applied active ingredients at different stages of sweetpotato production. High-performance liquid chromatography analyses revealed that the average detected residues for all the tested active ingredients and application timings fell under the maximum residue level thresholds for the United States, Canada, and the EU but not the United Kingdom. In the field experiments, fungicide treatments were not significantly different from nontreated plots for plot vigor, percentage disease incidence, or yield. Although the residues from the three tested products in this study were not a concern for U.S., EU, and Canadian markets when applied during sweetpotato field production, further research is needed to determine their potential as an effective management tool for sweetpotato black rot.

  PublisherDOI

• Confirmation and distribution of paraquat-resistant Italian ryegrass (<i>Lolium perenne</i> L. ssp. <i>multiflorum</i>) in North Carolina

  Weed Technology · 2025-01-01 · 1 citations

  articleOpen access

  Abstract Italian ryegrass is a troublesome weed species commonly found across the United States. In North Carolina, biotypes resistant to herbicides from Groups 1, 2, and 9 have been confirmed. In fall 2020, multiple growers reported unsatisfactory control of Italian ryegrass after sequential burndown applications of paraquat in the Southern Piedmont region of the state. The objectives of this study were to confirm the presence of a paraquat-resistant Italian ryegrass biotype in the state through a whole-plant dose–response bioassay and to characterize the response of Italian ryegrass accessions from the same region to commonly used burndown herbicides. Greenhouse studies were conducted at the North Carolina State University weed science laboratories to evaluate the response of three putative paraquat-resistant Italian ryegrass biotypes (B, H, SB) and four putative susceptible biotypes (S1, S2, S3, and S4) to paraquat rates ranging from 52.5 to 26,880 g ai ha −1 and the response of 38 accessions to clethodim (271 g ai ha −1 ), glyphosate (1,260 g ae ha −1 ), glufosinate (880 g ai ha −1 ), nicosulfuron (34 g ai ha −1 ), and paraquat (840 g ai ha −1 ). The effective paraquat dose required to reduce biomass by 50% (GR 50 ) for the putative paraquat-resistant biotypes ranged from 570 to 1,729 g ai ha −1 , equivalent to 19- to 58-fold more resistant to paraquat compared to the average GR 50 of susceptible biotypes. This study confirms the presence of paraquat-resistant Italian ryegrass in North Carolina. Results from the accessions study reveal that 29% of biotypes tested were resistant to paraquat, all of which also exhibited resistance to glyphosate and nicosulfuron. Additionally, a wide distribution of multiple herbicide–resistant biotypes was observed in the Southern Piedmont region, with 97% and 74% of accessions tested resistant to ≥1 and ≥2 sites of action, respectively.

  PublisherOA PDFDOI

• Methyl Isothiocyanate Concentration, Distribution, and Persistence in Sandy Soil as Influenced by Dazomet Post-application Practices

  HortTechnology · 2025-02-12

  articleOpen access

  Dazomet is a fumigant commonly used to control soil seedbanks and plant tissues of weed species in highly infested turfgrass areas. This fumigant reacts with water in the soil when in the presence of oxygen and releases methyl isothiocyanate (MITC) gas that kills seeds and plant tissues within the soil. Previous studies have reported varying levels of weed control by dazomet. As MITC is highly water soluble, mobile in soil, and volatile, inconsistencies in dazomet efficacy may be related to post-application practices of tilling, rolling, irrigation, and tarping. Therefore, the objective of this study was to analyze the effect of two practices commonly performed following dazomet application: tarp treatment (tilling, rolling, irrigation, and tarping), and water-seal treatment (post-irrigation at 0, 1, 2, and 3 days after application) on MITC concentration, distribution, and persistence in sandy soil. Field studies were conducted at Sandhills Research Station in Jackson Springs, NC, USA, in 2022 and 2023. MITC concentration and persistence varied between treatments and years. In 2022, MITC concentrations were notably higher in the tarp treatment compared with the water-seal treatment, whereas in 2023, the difference between treatments was less pronounced and more soil depth– and sample timing–dependent. Both treatments presented longer persistence, up to 168 hours after application (HAA), in 2023 compared with 120 HAA in 2022. In addition, MITC was highly concentrated in the top 15 cm of the soil and was detected as deep as 31 cm down from the soil surface in both treatments across both years.

  PublisherDOI

• Downslope lateral movement of tetflupyrolimet and pronamide in turfgrass

  Weed Technology · 2025-01-01

  articleOpen access

  Abstract Tetflupyrolimet is a novel herbicide that inhibits dihydroorotate dehydrogenase in susceptible weeds, including those in warm-season turfgrass and rice. Given that warm-season species are managed alongside cool-season species that may be sensitive to tetflupyrolimet, research on its lateral movement within turfgrass is warranted. Field experiments were conducted in spring 2023 and 2024 at North Carolina State University to evaluate the potential downslope movement of tetflupyrolimet (400 g ai ha −1 ) compared with that of pronamide (1,160 g ai ha − ¹), an herbicide that is known to move downslope. The studies took place on a 9.5% sloped plot of hybrid bermudagrass that had been established on Cecil sandy loam soil, under two moisture regimes at application: field capacity (≈34% volumetric water content) and saturation (≈46% volumetric water content). Before experimentation, the aboveground hybrid bermudagrass canopy was mechanically removed, and perennial ryegrass was planted as an indicator species. Herbicides were applied to treated areas (2.2 m 2 ) upslope of data collection areas (8.6 m 2 ), with subsequent irrigation and rainfall (2.5 cm total) 24 h after application. Downslope movement was assessed at 2, 4, 6, and 8 wk after treatment via perennial ryegrass mortality assessments made via grid (15 cm 2 ) count. Downslope distances associated with a 50% probability of perennial ryegrass mortality (mortality 50 ) were 1.2 to 3.6 times greater for pronamide compared to tetflupyrolimet. The maximum distance tetflupyrolimet moved was 1.1 m (regardless of soil moisture condition) each year. Comparatively, maximum downslope movement distance s for pronamide were 1.5 to 1.65 m under saturated conditions and 1.5 to 1.8 m at field capacity. Overall, these findings suggest a 1.1-m buffer from sensitive species is likely sufficient to prevent undesirable injury following tetflupyrolimet applications to hybrid bermudagrass under conditions similar to this study.

  PublisherOA PDFDOI

• Cover crops and fall residual herbicides for managing Italian ryegrass

  Weed Technology · 2025-01-01 · 1 citations

  articleOpen access

  Abstract North Carolina growers have long struggled to control Italian ryegrass, and recent research has confirmed that some Italian ryegrass biotypes have become resistant to nicosulfuron, glyphosate, clethodim, and paraquat. Integrating alternative management strategies is crucial to effectively control such biotypes. The objectives of this study were to evaluate Italian ryegrass control with cover crops and fall-applied residual herbicides and investigate cover crop injury from residual herbicides. This study was conducted during the fall/winter of 2021–22 in Salisbury, NC, and fall/winter of 2021–22 and 2022–23 in Clayton, NC. The study was designed as a 3 × 5 split-plot in which the main plot consisted of three cover crop treatments (no-cover, cereal rye at 80 kg ha −1 , and crimson clover at 18 kg ha −1 ), and the subplots consisted of five residual herbicide treatments (S-metolachlor, flumioxazin, metribuzin, pyroxasulfone, and nontreated). In the 2021–22 season at Clayton, metribuzin injured cereal rye and crimson clover 65% and 55%, respectively. However, metribuzin injured both cover crops ≤6% in 2022–23. Flumioxazin resulted in unacceptable crimson clover injury of 50% and 38% in 2021–22 and 2022–23 in Clayton and 40% in Salisbury, respectively. Without preemergence herbicides, cereal rye controlled Italian ryegrass by 85% and 61% at 24 wk after planting in 2021–22 and 2022–23 in Clayton and 82% in Salisbury, respectively. In 2021–22, Italian ryegrass seed production was lowest in cereal rye plots at both locations, except when it was treated with metribuzin. For example, in Salisbury, cereal rye plus metribuzin resulted in 39,324 seeds m –2 , compared to ≤4,386 seeds m –2 from all other cereal rye treatments. In 2022–23, Italian ryegrass seed production in cereal rye was lower when either metribuzin or pyroxasulfone were used preemergence (2,670 and 1,299 seeds m –2 , respectively) compared with cereal rye that did not receive an herbicide treatment (5,600 seeds m –2 ). cereal rye ( Secale cereale L.) and crimson clover ( Trifolium incarnatum L.)

  PublisherOA PDFDOI

• Soil texture effects on tetflupyrolimet efficacy in turfgrass

  Weed Science · 2025-01-01

  articleOpen access

  Abstract Tetflupyrolimet is a novel herbicide that inhibits dihydroorotate dehydrogenase (DHODH), interfering with de novo pyrimidine biosynthesis in susceptible plants. While tetflupyrolimet efficacy for preemergence grassy weed control in rice ( Oryza sativa L.) and managed turfgrass systems has been explored, there is minimal information regarding effects that edaphic factors may have on activity, particularly those pertaining to soil hydraulics. Dose–response experiments revealed 6- to 8-fold differences in tetflupyrolimet activity on annual bluegrass ( Poa annua L.) due to soil texture, with higher activity reported following applications to sand compared with clay loam. Higher tetflupyrolimet activity in sand could be related to matric potential, as activity following applications to plants growing in sand exceeded that observed on clay loam across a wide range of volumetric water contents (15% to 60%). Once volumetric water content increased to ≥ 80%, no differences in tetflupyrolimet activity were detected between soils, suggesting that post-application irrigation could mitigate potential reductions in efficacy on finer-textured soils when moisture is limited. These findings underscore that soil texture and, consequently, moisture retention affect tetflupyrolimet activity to the extent that application rates could vary based on soil texture in turfgrass systems. Further research exploring a broader range of soil types and field conditions is warranted to refine tetflupyrolimet rate recommendations based on soil type.

  PublisherOA PDFDOI

• Motivations and barriers to integrated management of annual bluegrass in sports fields: US survey findings

  Urban forestry & urban greening · 2025-05-23 · 1 citations

  article
  PublisherDOI

Frequent coauthors

• James T. Brosnan

  University of Tennessee at Knoxville

  45 shared

• Fred H. Yelverton

  North Carolina State University

  42 shared

• Matthew D. Jeffries

  36 shared

• Gregory K. Breeden

  University of Tennessee at Knoxville

  15 shared

• Matthew T. Elmore

  Rutgers, The State University of New Jersey

  14 shared

• Khalied A. Ahmed

  North Carolina State University

  13 shared

• James P. Kerns

  North Carolina State University

  13 shared

• Aaron J. Patton

  12 shared

Labs

• Crop and Soil SciencesPI