Flurprimidol [alpha-(1-methylethyl)-alpha-(4-(trifluoromethoxyphenyl)-5-pyrimidinemethanol] is a commercially available Type II plant growth regulator (PGR) (Rademacher, 2000) registered for use on golf course turf, coniferous and deciduous trees, established landscape ornamental plants and shrubs, and ornamental plants grown in containers (Anonymous, 1989). Totten et al. (2006) reviewed the physiological PGR effects of flurprimidol and stated that flurprimidol is predominantly root absorbed. Several publications have reviewed the literature about the use of flurprimidol in turf (Bigelow et al., 2007; McCullough et al., 2004; Totten et al., 2006) and ornamentals (Krug et al., 2005a, 2005b, 2007).
Flurprimidol is a bioisosteric pyrimidine analog of a triazole (Leroux et al., 2005). It has a water solubility of 120 to 140 mg·L−1 across a pH range of 4 to 7, has a half-life ranging from 5 d to 1.5 years depending on the environment, and was mobile in nonvegetated loam soil (Anonymous, 1989; Footprint, 2008). Chand and Lembi (1991), using a wettable powder formulation, indicated 88% dissipation of flurprimidol within 4 weeks of application and that the majority remained in the top 5 cm of sand. Data reported by the initial registrant indicated that flurprimidol can move to depths of at least 30 cm in terrestrial soil (Chand and Lembi, 1991).
Granular formulations of herbicides and PGRs are used to promote controlled release and reduce the number of applications (Gilliam et al., 1992; Keel et al., 1998). Granular herbicide formulations include oryzalin, flumioxazin, isoxaben, metolachlor, pendimethalin, imazapyr, tebuthiuron, ethalflurlin, diuron, and various combinations of these chemistries [Weed Science Society of America (WSSA), 2007]. Herbicidal activity of each is dependent on chemical properties and formulation. For example, among the dinitroaniline herbicides, pendimethalin has greater water solubility (0.275 mg·L−1) and lower volatility (WSSA, 2007), which makes it more conducive for granular application in ornamental container production systems.
For flurprimidol granular products, the exact formulation properties are confidential, being best described as an inert granule coated with flurprimidol at 0.33% by weight. As previously described, flurprimidol has moderate water solubility, but also activity at low concentrations (Lembi and Chand, 1992; Nelson, 1996, 1997), making it ideal for use as a PGR applied as a granular formulation. However, there is no information available about flurprimidol release characteristics and movement with respect to soil and organic media layers such as mulch and other soil barriers and covers, which are often used in landscape ornamental beds. The objective of this research was to determine flurprimidol dissipation rates from a flurprimidol-coated granule and to compare directly the movement of flurprimidol in sand, pine bark, and hardwood bark.
Anonymous 1989 Flurprimidol CAS No. 56425-91-3 February 22, 1989 US EPA Pesticide Fact Sheet 4 June 2008 <http://www.fluoridealert.org/pesticides/flurprimidol.epa.facts.1989.htm>.
Barrett, J.E. 1982 Chrysanthemum height control by ancymidol, PP333, and EL-500 dependent on medium composition HortScience 17 896 897
Bigelow, C.A., Bunnell, B.T. & Hardebeck, G.A. 2007 Monthly flurprimidol applications reduce annual bluegrass populations in a creeping bentgrass fairway Applied Turfgrass Science.
Branham, B.E. & Lickfeldt, D.W. 1997 Effect of pesticide-treated grass clippings used as a mulch on ornamental plants HortScience 32 1216 1219
Brake, J.D., Boyle, C.R., Chamblee, T.N., Schultz, C.D. & Peebles, E.D. 1992 Evaluation of the chemical and physical properties of hardwood bark used as a broiler litter material Poult. Sci. 71 467 472
Chand, T. & Lembi, C.A. 1991 Gas chromatography determination of flurprimidol in a submersed aquatic plant (Myriophyllum spicatum), soil, and water J. Plant Growth Regul. 10 73 78
Daniels, W.L. & Wright, R.W. 1988 Cation exchange properties of pine bark growing media as influenced by pH, particle size, and cation species J. Amer. Soc. Hort. Sci. 113 557 560
Dermiyati, S.K. & Yamamoto, I. 1997 Relationships between soil properties and sorption behavior of the herbicide halosulfuron–methyl in selected Japanese soils J. Pestic. Sci. 22 288 292
Footprint 2008 The FOOTPRINT Pesticide Properties DataBase Database collated by the University of Hertfordshire as part of the EU; funded FOOTPRINT project (FP6-SSP-022704) 9 Sept. 2008 <http://www.eu-footprint.org/ppdb.html>.
Gilliam, C.H.D.C.F. & Beasley, A. 1992 Nontarget herbicide losses from application of granular Ronstar to container nurseries J. Environ. Hort. 10 175 176
Grey, T.L., Wehtje, G.R., Hajek, B.F., Gilliam, C.H., Kever, G.J. & Pace, P. 1996 Adsorption, mobility, and filtration of metolachlor in container media J. Amer. Soc. Hort. Sci. 121 478 482
Keel, K.R., Gilliam, C.H., Wehtje, G.R., Grey, T.L., Keever, K.J. & Eakes, D.J. 1998 Herbicide adsorption and release properties of five oxadiazon-coated fertilizers J. Environ. Hort. 16 230 234
Krug, B.A., Whipker, B.E., McCall, I. & Dole, J.M. 2005a Comparison of flurprimidol to ancymidol, paclobutrazol, and uniconazole for tulip height control HortTechnology 15 370 373
Krug, B.A., Whipker, B.E., McCall, I. & Dole, J.M. 2005b Comparison of flurprimidol to ethephon, paclobutrazol, and uniconazole for hyacinth height control HortTechnology 15 872 874
Lembi, C.A. & Chand, T. 1992 Response of hydrilla and Eurasian watermilfoil to flurprimidol concentration and exposure times J. Aquat. Plant Manage. 30 6 9
Leroux, F., Jeschke, P. & Schlosser, M. 2005 ∝-Fluorinated ethers, thioethers, and amines: Anomerically biased species Chem. Rev. 105 827 856
Leroux, F.R., Manteau, B., Vors, J.P. & Pazenok, S. 2008 Trifluoromethyl ethers—Synthesis and properties of an unusual substituent Beilstein J. Org. Chem.
McCullough, P.E., Liu, H. & McCarty, L.B. 2004 Response of ‘TifEagle’ bermudagrass to seven plant growth regulators HortScience 39 1759 1762
Mueller, T.C., Shaw, D.R. & Witt, W.W. 1999 Relative dissipation of acetochlor, alachlor, metolachlor and SAN 582 from three surface soils Weed Technol. 13 341 346
Rademacher, W. 2000 Growth retardants: Effect on gibberellin biosynthesis and other metabolic pathways Annu. Rev. Plant Physiol. Plant Mol. Biol. 51 501 531
Totten, F.W., Toler, J.E. & McCarty, L.B. 2006 ‘Tifway’ bermudagrass growth regulation with the use of trinexapac-ethyl and flurprimidol Weed Technol. 20 702 705