2022 TTREEE Final Report

The effect of plant growth regulator application strategies and cultivation practices on trafficked sports field playability

Chase Straw, Ph.D., Weston Floyd, CSFM, and Emmanuel Alabi Texas A&M University, Soil and Crop Sciences, College Station, TX

PROBLEM: Trinexapac-ethyl (TE) is one of the most widely applied plant growth regulators in turfgrass. It is a foliar absorbed, Type II plant growth regulator that disrupts gibberellin biosynthesis resulting in reduced cell elongation. TE has been found to reduce turfgrass mowing requirements, enhance green color, and improve heat, cold, drought, and shade stress tolerance (Schiavon et al., 2014). Additionally, TE causes increased specific leaf weight, tillering, and total root length (Beasley et al., 2005), leading many to hypothesize that TE may increase turfgrass wear tolerance and recover on sports fields (Brosnan et al., 2005). However, minimal research has been conducted investigating benefits of TE on newer hybrid bermudagrass cultivars under simulated wear. These cultivars have more aggressive growth habits and typically require routine cultivation practices (e.g., verticutting, raking) for density management (e.g., tight canopies influencing cleat-surface interactions), which is may also be impacted by TE applications.

Furthermore, there is confusion amongst sports field managers concerning the reapplication intervals and rates of TE to fully maximize its potential. A preliminary survey conducted by PI Straw and Co-PI Floyd with sports field managers who maintain bermudagrass fields in the southeast United States found that 87% of responders applied TE, but 33% reapplied based on label recommendation (i.e., every 4 weeks) and 47% reapplied based on turfgrass growth response (e.g., growing degree day calculator or visual clipping yield; the remaining 20% did not answer the question). Due to concerns about turfgrass recovery when TE is applied, 40% of responders decreased their TE rate based on anticipated traffic. Nevertheless, 40% of responders did not adjust their rate based on anticipated traffic, and the remaining either increased the TE rate or did not answer the question. Cultivation practices ranged from once per year to twice per month.

OBJECTIVES: The objective of this research was to determine the effect of TE rate, reapplication interval, and stoppage, as well as cultivation practices, on trafficked hybrid bermudagrass American football field playability. Two separate scenarios were investigated: 1) a collegiate/professional field and 2) a park and recreation/K-12 field.

METHODS: Research was conducted in 2021 and 2022 at the Turfgrass Field Laboratory in College Station, TX; however, only results from 2021 will be presented in this report. The collegiate/professional field scenario study was conducted on ‘Latitude 36’ hybrid bermudagrass mowed at 0.5” and grown on a sand cap. The park and recreation/K-12 field scenario was conducted on ‘TifTuf’ hybrid bermudagrass mowed at 0.75” and grown on a native soil (sandy loam). The study design and all treatments were similar for each field scenario.