Phytotoxicity of Herbicides, Fungicides, and Insecticides on Ornamental Monocot Species in Southeastern U.S. for Interregional Research Program (IR-4)

The Interregional Research Project (IR-4) is a joint USDA–ARS and Land Grant Institution program that evaluates agricultural chemicals and expands sustainable pest management technologies for growers by providing efficacy and phytotoxicity data needed for registered use on specialty crops that include floral, fruit, herb, nursery, nut and vegetables.  In the last ten years, the IR-4 project on the U.S. southeastern coastal plain has completed 24 phytotoxicity experiments on five ornamental monocot species including Daylily, Hosta, Lily, Liriope, and Canna using various agricultural chemicals.  Eleven herbicides were applied at label rates as either a broadcast granular or as “over-the-top” foliar sprays.  Over this same period, two fungicide and one insecticide were applied to monocots using either foliar or drench applications.  Field experiments were designed as randomized complete blocks with application method and pesticide treatments assigned to a specific cultivar or monocot species. Phytotoxicity was measured on a scale of 0 to 10 (0 = no injury; 10 = dead) at various intervals after each application. Plant height and width were also measured at the beginning and end of each experiment to assess any adverse chemical impact on plant growth and marketability.  Data were analyzed in MS Excel or ARM using a t-test and results indicated significant differences in phytotoxicity or marketability between the controls and some of the chemical treatments.  These phytotoxicity data are used to support new registration or re-registration of reduced risk pesticides on ornamental horticultural crops.  Regional data are compiled from around the U.S. and ultimately submitted to the U.S. Environmental Protection Agency to facilitate the registration or re-registration of active ingredients.