Research Summary Abstract
Pendimethalin has been registered in the United States since 1994 for uses in and around environmental horticulture plants in production nurseries and in landscapes. Between 1981 and 2008, the IR-4 Project has conducted over 469 trials using two granular formulations (Corral 2.68G and Pendulum 2G), two liquid formulations (Pendulum AquaCap and Prowl 4E) and a wettable dry granular formulation (Pendulum WDG). Between 2014 and 2018, 70 trials were conducted on ornamental grasses to determine crop safety of the Pendulum 2G formulation. This summary is an update of the second summary, issued in 2017, across all the available data generated through IR-4 since screenings began in 1981.
Eighty-seven plant species or genera exhibited no or minimal, transitory phytotoxicity to over the top applications of Corral 2.68G and Pendulum 2G formulations. Of these, 22 species or genera are not on the current Pendulum 2G label. Two species (Phlox paniculata and Rhodiola pachyclados) exhibited significant injury to Pendulum 2G. Thirty-seven plant species or genera exhibited no or minimal transitory phytotoxicity to applications of Pendulum AquaCap and Pendulum WDG formulations. All these ornamentals are currently listed on the Pendulum AquaCap label. One species (Stachys byzantina) exhibited phytotoxicity at 2 lb ai per acre and higher rates.Twenty plant species or genera exhibited no or minimal transitory phytotoxicity to applications of Prowl 4E. Of these, one (Paeonia sp.) is not currently listed on the label.