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Leaf Extension Rate May Help Determine When Low Wild Oat Herbicide Rates Will Be Effective1

Published online by Cambridge University Press:  20 January 2017

K. Neil Harker*
Affiliation:
Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, Alberta, Canada T4L 1W1
Robert E. Blackshaw
Affiliation:
Agriculture and Agri-Food Canada, Lethbridge Research Centre, Box 3000, Lethbridge, Alberta, Canada T1J 4B1
*
Corresponding author's E-mail: harkerk@agr.gc.ca

Abstract

Determination of the active growth state of weeds may lead to more reliable predictions of herbicide efficacy. Experiments were conducted at Lacombe and Lethbridge, Alberta, Canada, from 1996 to 1998 to determine if wild oat leaf extension (growth) rate could be used to predict the efficacy of imazamethabenz and ICIA 0604. As expected, wild oat control increased and wild oat biomass decreased with increasing imazamethabenz and ICIA 0604 rates. Mean wild oat growth rates ranged from 6 to 44 mm over a 24-h time interval. Wild oat control at 25% of the recommended doses of ICIA 0604 or imazamethabenz increased as wild oat growth rate increased. However, wild oat growth rate did not influence herbicide efficacy at higher herbicide rates. Regression analysis confirmed that wild oat control at the lowest application rates increased 6 or 14% for every 10 mm of wild oat growth during the 24 h preceding herbicide application of ICIA 0604 or imazamethabenz, respectively. Covariance analysis confirmed the influence of wild oat growth rate on wild oat control by imazamethabenz but not by ICIA 0604. Monocot leaf extension rates may be useful for predicting herbicide efficacy in integrated weed management or decision support systems.

Information

Type
Research
Copyright
Copyright © Weed Science Society of America 

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