ABSTRACTAthletic field paints are applied to turf surfaces with little or no acute injury. However, field managers notice chronic declines in turfgrass health after repeated applications. This study examines athletic field paint impacts on spectral quality and associated turfgrass photosynthesis. Growth chamber experiments evaluated effects of red and white athletic field paint as well as one, two, three, and four repeated weekly applications on total canopy photosynthesis (TCP) of perennial ryegrass (Lolium perenne L.). Paint treatments were applied weekly for 6 wk with TCP recorded 24 h after each application using a gas exchange system. Spectroradiometry experiments evaluated reflection, absorption, and transmission of light at various wavelengths based on paint color, dilution, and thickness. Over a six week period all treatments reduced TCP based on color (P ≤ 0.0001) and dilution (P ≤ 0.0001). Red no‐dilution paint produced a 75% reduction in TCP over 6 wk while white 1:1 diluted paint only produced a 19% reduction. Spectroradiometry data suggests this is likely due to reductions in photosynthetically active radiation (PAR) with red paint absorbing 51% of incident PAR while transmitting and reflecting 6 and 43%, respectively. White paint transmitted 5% of PAR while reflecting 95%. Alterations in light spectral quality resulting from athletic field paint applications can impact PAR, which may result in reduced turfgrass health.