Studies were conducted to evaluate growth and reproductive capabilities of creeping rivergrass in response to rice herbicide programs. Creeping rivergrass grown from single-node stolon segments, multiple-node stolon segments, and rhizomes was treated with various herbicides to evaluate activity on subsequent growth and viability of nodes produced from treated plants. Comparison with the nontreated, cyhalofop, glyphosate, and imazethapyr reduced creeping rivergrass fresh weight by more than 84 to 96%. Glyphosate reduced sprouting of nodes from treated plants 93% compared with nontreated plants. Activity from these herbicides may decrease when applied to plants grown from rhizomes versus rhizome clusters. Plants treated with cyhalofop, glyphosate, and imazethapyr had reduced fresh weight of 36 to 46% when plants were grown from a rhizome cluster, and 69 to 90% when plants were grown from a single rhizome segment, compared with nontreated. Cyhalofop and glyphosate reduced node sprouting by 81 to 98% of nontreated, regardless of parent structure.

A study was established to evaluate herbicides registered for barnyardgrass control in rice for activity on creeping rivergrass. Treatments included 208 g ai/ha cyhalofop early POST (EPOST) followed by (fb) 315 g/ha cyhalofop late POST (LPOST), 22 g ai/ha bispyribac EPOST fb 22 g/ha bispyribac LPOST, 66 g ai/ha fenoxaprop EPOST fb 86 g/ha fenoxaprop LPOST, 70 g ai/ha imazethapyr EPOST fb 70 g/ha imazethapyr LPOST and 50 g ai/ha penoxsulam mid-POST (MPOST). Each POST program was evaluated with and without 448 g ai/ha clomazone PRE. Barnyardgrass control, averaged over days after treatment (DAT), was 88 to 92% with the addition of clomazone PRE. Clomazone applied PRE followed by two applications of cyhalofop controlled creeping rivergrass at 91%. Creeping rivergrass control was less than 75% at 35 to 49 DAT. This response indicates only suppression of creeping rivergrass is achieved with the herbicide programs evaluated in this study.