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1 January 2007 Timing and Dose of Metolachlor Affect Rigid Ryegrass (Lolium Rigidum) Control in Wheat
Bhagirath S. Chauhan, Gurjeet S. Gill, Christopher Preston
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The efficacy of metolachlor on rigid ryegrass was determined under a no-till seeding system in an experiment conducted in 2004 and 2005 in South Australia. Metolachlor at a rate of 0.48 and 0.96 kg ai/ha was applied at 40 or 46 d (very early preplant, VEPP) and 20 or 23 d before crop sowing (early preplant, EPP), and at sowing (preplant, PP) in 2004 and 2005; the herbicide was incorporated by sowing. The control of rigid ryegrass was greater than 80% when metolachlor was applied PP; however, that application resulted in phytotoxic effects on emergence and yield of wheat; metolachlor was more phytotoxic when applied at 0.96 kg/ha than at 0.48 kg/ha. Metolachlor applied EPP provided 71 to 83% rigid ryegrass control, whereas VEPP application provided only 33 to 49% control. Reduction in wheat grain yield was not observed at these application times. This study indicates that metolachlor at 0.48 kg/ha could be safely applied around 20 d before crop sowing to selectively control rigid ryegrass in wheat.

Nomenclature: Metolachlor, rigid ryegrass, Lolium rigidum Gaud. LOLRI, wheat, Triticum aestivum L. ‘Krichauff’

Bhagirath S. Chauhan, Gurjeet S. Gill, and Christopher Preston "Timing and Dose of Metolachlor Affect Rigid Ryegrass (Lolium Rigidum) Control in Wheat," Weed Technology 21(1), 225-229, (1 January 2007).
Received: 11 March 2006; Accepted: 1 August 2006; Published: 1 January 2007

weed control
weed emergence
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