Herbicide Effects On Soil Moisture Use in Bermuda Grass Cultivar ‘Princess 77'.

Soil moisture probes were used to investigate the effects of common turfgrass herbicides on soil moisture status and growth of hybrid Bermuda grass, Cynodon dactylon (L.) Pers., cultivar ‘Princess-77’. Six post-emergent herbicide treatments (consisting of 3 herbicides applied individually, 2 combinations and a control) were applied to field plots of Bermuda grass recently established on clay soils. All treatments contained 0.25% surfactant and all plots were relatively weed-free at the time of treatment application. The sedge herbicide ‘Sedge-Hammer’ with the active ingredient halosulfuron-methyl was found to increase the rate of soil moisture loss when applied individually or in combination with another herbicide, ‘MSMA’. This effect was not observed with the other herbicides included in this study, ‘MSMA’ and ‘Manage’, applied individually or together. In a follow-up experiment, the two formulations of halosulfuron-methyl (Manage and Sedge-Hammer) were applied with surfactant to Bermuda grass established in 16.2cm x 45cm cylindrical lysimeters filled with sand. Control treatments with and without surfactant were also included in this study. The moisture content of the sand was increased by application of the surfactant containing treatments. The decline in soil moisture content during the intervals between watering was steeper for ‘Sedge-Hammer’ compared to the other treatments. There were no significant differences in the accumulated dry mass of clippings among treatments although quality characteristics were affected. Tissue moisture content for Sedge-Hammer treated turfgrass fell steadily during the weeks following treatment application but was more variable for the other treatments as the dry season progressed. Since both ‘Sedge-Hammer’ and ‘Manage’ contain the same active ingredient, it is likely that the different responses observed were due to differences in product formulation. These results have implications for product selection under water-limited environments and may suggest an additional water management tool for sports fields.