Improved post-emergence weed control in dry bulb onions.
Posted on June 4, 2014 by Bernard Zandstra, Michigan State University Extension, Department of Horticulture
The Michigan Department of Agriculture and Rural Development (MDARD) has approved a Section 24c Special Local Needs (SLN) label for application of GoalTender at the one leaf stage of dry bulb onions. This will allow earlier application on young onions. The current label allows GoalTender application at the onion two-leaf stage for control of broadleaf weeds.
Several persistent broadleaves, including ladysthumb (smartweed), common lambsquarters, Virginia pepperweed, and marsh yellowcress, germinate early in the season and become established before the two-leaf stage of onion. Those weeds are normally very difficult to control with GoalTender, but are more susceptible in their cotyledon to two-leaf stage. By the onion two-leaf stage, they have become well-established and may have to be removed by hand. By applying GoalTender at the onion one-leaf stage, many of them can be eliminated.
Our research over the past six years indicates a consistent increase in onion yield from GoalTender application at the onion one-leaf stage as a result of less weed competition and less crop injury from cultivation and hand weeding. This SLN label was issued too late for most growers this year since most onions have passed the one-leaf stage. Growers should plan to use GoalTender in this manner in succeeding years.
Under the new label, GoalTender may be applied at a rate of 4-6 fluid ounces per acre (0.125-0.188 pounds active ingredient per acre) when onions have one fully extended true leaf and the second true leaf is emerging. GoalTender may be applied again at the two- to three-leaf stage and again at the four- to six-leaf stage. Do not exceed a total of 16 fluid ounces (0.5 pounds active ingredient) of GoalTender per season in all applications. The preharvest interval (PHI) is 42 days.
Growers must assume all liabilities for crop damage or injury under provisions of this label. Growers must have a copy of this label in their possession before use. Please contact chemical suppliers or Michigan State University Extension educators for copies of the label.
This article was published by Michigan State University Extension. For more information, visit http://www.cnchemicals.com/. To contact an expert in your area, visit http://www.cnchemicals.com/, or call 888-MSUE4MI (888-678-3464).