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Title: Weed control trials in transplanted onions in Oklahoma

Author
item SHREFLER, J.W. - OSU, LANE,OK
item Webber Iii, Charles

Submitted to: Southern Region of the American Society for Horticultural Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2004
Publication Date: 6/1/2004
Citation: Shrefler, J., Webber III, C.L. 2004. Weed control trials in transplanted onions in Oklahoma. 64th Annual Meeting of the American Society for Horticultural Science, Southern Region. 39(3):661.

Interpretive Summary:

Technical Abstract: Recent interest in establishing commercial bulb onion production in Oklahoma has prompted the need to develop suitable weed management recommendations for this crop. Trials were conducted in 2001 and 2003 at Lane, OK and in 2002 at Calvin, OK to address this need. Objectives were to evaluate chemical weed control strategies in transplanted onions using 1) the currently approved herbicides Prowl (pendimethalin) and Goal (oxyfluorfen) and 2) the herbicide Frontier (dimethenamid) which is currently in process of being registered for use in onions. Treatments were Prowl @ 1 pint/acre preemergence (PRE) followed by (fb) Prowl @ 1 pint/acre postemergence (POST), Prowl @ 2 pint/acre PRE, Prowl @ 1 pint/acre + Goal @ 1 pint/acre PRE, Goal @ 2 pints/acre PRE, Frontier @ 1 pint/acre + Prowl @ 1 pint/acre PRE, Frontier @ 2 pint/acre + Prowl @ 1 pint/acre PRE, Frontier @ 1 pint/acre PRE fb Goal @ 2 pint/acre POST and Frontier @ 2 pint/acre PRE fb Goal @ 2 pint/acre POST. Based on visual evaluations of weed control, all treatments consistently provided excellent control of pigweeds and annual grasses except for Prowl and Goal when applied alone. For yellow nutsedge (Cyperus esculentus), treatments that included Frontier provided best control. For broadleaf weeds including Pennsylvania smartweed (Polygonum pensylvanicum) and cutleaf groundcherry (Physalis angulata) the Prowl + Goal treatment and all treatments that included Frontier provided excellent control. For toothed spurge (Euphorbia dentata), Frontier and Goal treatments applied at 2 pint rates provided the best, but not complete control. Onion yield was increased significantly by several treatments in each study. The major effect on increased yield was to increase yield of large (>3 inch diameter) bulbs.