2017 – 02a Foliar Applications of N and K for improving Cold Tolerance of annual bluegrass (Poa annua L.)

Currently there is conflicting information on the effects of Nitrogen (N) focused fall fertility programs for improving cold tolerance during the acclimation and spring recovery (deacclimation) time-frames. In general, the literature shows a trend of positive effect for improving frost hardiness during the acclimation period with N applications (Taulavuori, et al., 2004). For example, early research by Carroll (1943) found fall application rates of N directly correlated with cold tolerance, and Carroll and Welton (1939) found high crown hydration levels were associated with increased risked to winter injury.

A granular-focused N and K trial at the PTRC found that applying 4.88gNm-2yr-1 at biweekly rates of 1.22gNm-2 in combination with 4.88 – 9.76 gKm-2yr-1 at biweekly rates of 1.22-2.44 gKm-2, resulted in optimum cold tolerance levels and good spring recovery on an annual bluegrass putting green. While the results were useful in determining the negative effects of too much or too little N and K applied during the fall acclimation process, the rates were too coarse to fine-tune a foliar-based fertility program. The proposed study aims to fine-tune these rates for superintendents that are using foliar-based fertility programs.