Onion Weed Control Funding Provided By: The ADOPT Fund of Saskatchewan Agriculture and Food and The Saskatchewan Vegetable Growers Association

Onion Weed Control Objectives ( ) - to demonstrate and compare efficacy and crop safety of pre- emergence herbicides in onions

Onion Weed Control Products demonstrated - Goal (oxyfluorfen) - Chateau (flumioxazin) - Buctril (bromoxynil) - Dual (metolachlor) - Prowl (pendimethalin)

Onion Weed Control Cultivars – Norstar and Copra Field - U of S Field Station - “standard” spectrum of weeds - field rotovated week ahead of seeding - direct seed crop in rows 0.5 m apart - just prior to crop emergence – burn off emerged weeds with glyphosate -

Onion Weed Control Maintenance - Overhead irrigated as required - 50 #/a N top-dressed in early July - sprayed with Quadris for botrytis

Onion Weed Control Sprayed - at 2 true leaf stage (mid-June) - repeat at 4-6 leaf stage (mid-July) - all stages and rates according to product label - applied with standard spray gear

Onion Weed Control Data collected - crop toxicity - weed counts/weights - onion yields Herbicides compared against an untreated Control

Onion Weed Control Results - high water table in both years crop generally healthy … but grew slowly crop struggled with disease and flooding through August – then took off - significant weed pressure throughout both growing seasons

Onion Weed Control Results no obvious crop toxicity for any product Chateau seemed to stunt/weaken plants - More disease on Chateau treated rows

Onion Weed Control Results - weeds change with season/plot Early = stinkweed, RRPW, -Later = mallow, dandelion and curled dock

Onion Weed Control Results - weeds change with season/plot Early = stinkweed, portulaca -Later = portulaca, pigweed and groundsel

2011

2012

Chateau Check

Goal Check

Onion Herbicides Conclusion - several effective pre-emergent herbicides available - Chateau and Goal provide outstanding control of wide range of broadleaf weeds.

Onion Herbicides – 2012

Onion Herbicides Conclusion - weed control is crucial in onions - there are some highly effective herbicides available for use in onions - watch for “hidden” costs of weed control - potential for damage to the crop … while tilling/pulling weeds … by herbicides