Syringing Kentucky Bluegrass: Frequency Impacts Canopy Temperature and Growth.

Conserving water is increasingly important in turfgrass management. Heat-stressed turf uses water less efficiently, but maintaining lower canopy temperatures can improve water efficiency and grass health. Kentucky bluegrass (Poa pratensis L.) is the most commonly planted turfgrass species. Unfortunately, it is susceptible to heat and water stress. This species thrives at about 22°C, but summer temperatures often exceed 32°C in a majority of the cool season climate in which this species is grown. When temperatures are excessively high, syringing with water is a known method to cool the canopy. The purpose of this experiment is to develop improved management practices by determining how temperatures decrease with syringing and how long they remain depressed. A greenhouse study was conducted with Kentucky bluegrass comparing an untreated control with a syringing rate of 2.9 mm applied once (12 or 2 pm), twice (12 and 2 pm), or three (12, 2 and 4 pm) times daily for four days. Canopy temperatures were measured every five minutes. Syringing was more effective when applied at 12pm, with temperatures above 32°C for 1.4 cumulative hours compared to 1.8 hours when syringing was done at 2pm. Syringing at both 12 and 2 pm reduced the time above 32°C to 0.7 hours while adding a third syringing event was less effective and resulted in 1 hour with temperatures above 32°C. Further study is underway to evaluate impacts on shoot and root biomass, verdure, NDVI, and water use efficiency.