Does Irrigating Dormant Bermudagrass Pay Off?.

Despite the inactivity and lack of transpiration of warm-season grasses during winter dormancy, the general recommendations are to keep the crown of the plant moist and active to avoid winter injury. A study was conducted at New Mexico State University to test the usefulness of this practice by investigating the effects of 4 irrigation regimes on spring green-up of Princess 77 bermudagrass (Cynodon dactylon L). The irrigation consisted of 3 mm applied either 1) once per week 2) once every 2 weeks or 3) once monthly. The control treatment received no irrigation. Each treatment was replicated 3 times. Percentage of green cover was determined every two weeks starting on March 13^th until 100% cover was reached. Moreover, on March 30^th daily irrigation was resumed based on reference ET for short grass to allow bemudagrass to fully recover. A sigmoidal model was found to best fit the data. The values were interpolated to determine day of the year to reach either 50% or 95% coverage. Statistical analyses indicate significant differences among treatments. Plots that were irrigated weekly reached 50% coverage 15, 19, and 24 days faster than plots irrigated biweekly, monthly or not at all, respectively. However, 95% coverage was reached equally fast for weekly and biweekly irrigated plots, compared to monthly irrigated plots and control plots. Our results indicate that small irrigation amounts applied either weekly or every other week during winter dormancy will result in faster spring green-up. However, more research is necessary to investigate irrigation frequency and how much water exactly is needed for earliest green-up.