Crown Moisture Thresholds of Tall Fescue Survival in Drought Conditions.

Tall fescue (Festuca arundinacea) has become a popular home lawn grass because of its deep root system which aids short-term drought avoidance. Compared to Kentucky bluegrass (Poa pratensis), tall fescue is not thought to a have strong dormancy response during long-term drought. The objectives of this study were to determine the critical crown moisture content for tall fescue survival during drought and determine how much weekly irrigation is required to sustain tall fescue survival during prolonged summer drought. A field study was conducted at the JSA Turf Research Center in Mead, NE during the summer of 2014. Plots were irrigated weekly with 0, 6.4, 12.7, 19.1, 25.4 mm of water, or replacement of 100% evapotranspiration (Et), all split into three applications weekly. The plot area was covered with a moveable rain-out shelter during precipitation events. Gravimetric crown moisture, volumetric soil water content, and soil water potential were correlated with turf survival to calculate a lethal moisture content at which 50% of the plants died (LCM₅₀). Dark green color index (DGCI) and turf quality (TQ) were also measured weekly. Crown moisture levels, DGCI, and TQ were correlated with turf survival to determine how much supplemental irrigation was required to ensure minimal crown moisture thresholds were met during the prolonged drought period.