The IR-4 program works to identify potential minor-use horticultural chemicals and evaluate them for phytotoxicity and efficacy. The objective of this experiment was to evaluate phytotoxicity and weed control of three unlabeled herbicides on field production of Hemerocallis spp. `Ming Toy'. Ten-cm pots of `Ming Toy' were planted into the field 16 July 2001. Each plot consisted of 3 plants per treatment with 6 replications in a completely random design. Each herbicide was analyzed as a separate experiment. Herbicide treatments consisted of clopyralid (0.14, 0.28, 0.56, or 1.1 kg·ha-1 a.i.), clethodim (125, 250, or 500 mL·L-1 a.i.), or bentazon (1.1, 2.2, or 4.4 kg·ha-1 a.i.). Data collected included weed number, percentage of weed coverage (% weed coverage), and phytotoxicity and foliar color ratings for `Ming Toy'. Clopyralid reduced total weed number 90 DAT although % weed coverage was similar or worse compared to the control treatment. Phytotoxicity 90 DAT was not significant for plants treated with clopyralid, but foliar color ratings were reduced. Application of clethodim to `Ming Toy' plots, regardless of rate, resulted in similar weed numbers compared to the control 49 DAT. Clethodim application, regardless of rate, reduced % weed coverage compared to the control treatment. Phytotoxicity 90 DAT was not significant, regardless of herbicide treatment, but foliar color ratings were lower for herbicide treated plants compared to the control. Bentazon, regardless of rate, reduced weed number and % weed coverage 49 DAT compared to the control. Phytotoxicity was similar to the control for plants treated with 1.1 kg·ha-1 a.i.
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