The interaction of nitrogen management with the use of plant growth regulation has been examined for the past three years. Pentia (mepiquat pentaborate) was applied beginning at first bloom in both 2003 and 2004 and had some adverse effects on cotton yield. In 2005, the initiation of PGR application was moved to the pin-head square growth stage to determine whether this timing could potential increase yields. Other research has shown some promise for the earlier applications. Both N rates and timing of N application have been included as components of the study.