Postemergence control failure of Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] with paraquat

Authors: ORGERON, ALBERT - LSU Agcenter; COCO, ALPHONSE - LSU Agcenter; FOSTER, MATTHEW - LSU Agcenter; Spaunhorst, Douglas

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2019
Publication Date: 6/1/2019
Citation: Orgeron, A.J., Coco, A.B., Foster, M.R., Spaunhorst, D.J. 2019. Postemergence control failure of Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] with paraquat [abstract]. Journal American Society of Sugarcane Technologists. 39:49.

Interpretive Summary:

Technical Abstract: Italian ryegrass [Lolium perenne L. ssp. Multiflorum (Lam.) Husnot] is a winter annual weed pest of sugarcane in Louisiana. Italian ryegrass begins emerging in mid-October and emergence has been observed as late as February. Postemergence chemical control options to manage Italian ryegrass in sugarcane is limited to paraquat. Several sugarcane producers have reported inadequate Italian ryegrass control with paraquat applied at 840 g ha-1, the recommended paraquat rate. In 2017, research was conducted at the LSU AgCenter’s Sugar Research Station to evaluate Italian ryegrass control with paraquat. Treatments were applied to 20-30 cm tall Italian ryegrass on February 20, 2017. Treatments included paraquat applied at three rates (840, 1120, and 1680 g ha-1) and two spray volumes (140 and 187 L ha-1). Visual control estimates were recorded 35 days after application. Regardless of spray volume, the 840 g ha-1 paraquat treatment (recommended rate) provided 22% Italian ryegrass control, whereas, the 1680 g ha-1 paraquat treatment controlled 52% of Italian ryegrass. These results show poor control of Italian ryegrass with paraquat, even when applied at 2X the recommended rate.