Response of Phyla nodiflora (L.) Greene (turkey tangle frogfruit) to post-emergence application of three graminicides

Abstract

Turkey tangle frogfruit (also known as simply frogfruit or fogfruit) (Phyla nodiflora (L.) Greene [Verbenaceae]) is a creeping herbaceous ground cover species native to Florida and the southeastern US. Frogfruit is becoming increasingly popular as a turfgrass alternative due to its low maintenance requirements, aesthetically pleasing flowers, high drought tolerance, attractiveness to pollinators and beneficial insects, and it has low pressure from the fungal pathogens and insect pests that damage conventional turfgrass. While frogfruit offers many advantages, common complaints among homeowners and landscape professionals are turfgrass encroachment from neighboring properties, re-emergence following conversion from a warm-season turfgrass to a frogfruit lawn, and difficulty managing annual and perennial grassy weeds in general. To increase adoption of frogfruit as a native lawn alternative, selective weed control options are needed. Therefore, the objective of this study was to evaluate 3 herbicides including sethoxydim, fluazifop-P-butyl, and topramezone to determine frogfruit growth and injury response following 2 sequential applications at increasing rates equivalent to 1×, 2×, and 4× the standard label rate. Results showed no injury or reduction in growth, determined by shoot biomass accumulation, following any treatment with sethoxydim or fluazifop-P-butyl throughout the experiment. However, topramezone treatment resulted in injury at all rates tested, consisting of bleached and stunted foliage following both the first application and increasing after the second application at all rates. Shoot dry weight data showed that topramezone reduced frogfruit growth by 43 to 73% in comparison with a non-treated control group. Overall, results show that fluazifop-P-butyl or sethoxydim would be suitable post-emergence herbicides for grassy weed control in a frogfruit lawn with little to no injury or growth reduction expected. Additional research is needed to determine the tolerance of frogfruit to additional post- and pre-emergence herbicides so that integrated weed management programs can be developed for this emerging native ground cover species.