ABSTRACT
Altering the growth and development of turfgrass through exogenous applications of various chemicals began with maleic hydrazide in 1945 and has been a research endeavor of turfgrass scientists for more than 60 years.1,2 The primary objective has been to restrict leaf growth and the subsequent need for frequent mowing. The earliest plant growth regulators (PGRs) labeled for use on turfgrasses, maleic hydrazide and mefl uidide, provided adequate shoot growth suppression but often caused unacceptable phytotoxicity and stand-density losses because of their ability to rapidly stop cell division and differentiation in meristematic regions.1 These cell-division inhibitors were
originally classifi ed as type I PGRs but are now known as class C materials.3 In fi ne turf, their use is now primarily limited to seedhead suppression. Our focus in this chapter will be on benefi cial effects of PGRs on stress physiology and performance of fi ne turf, so no further mention of class C PGRs will be made.
