New Dual Magnum herbicide labels for lettuce

Dual Magnum and Gramoxone Inteon labeled for head and leaf lettuce in Michigan.

The Michigan Department of Agriculture and Rural Development (MDARD) has requested, and the United States EPA has approved, a Crisis Exemption (Section 18) for use of Dual Magnum on established head and leaf lettuce in Michigan. The Crisis Exemption is in effect from May 16 to September 30, 2011. Under the Crisis Exemption, Dual Magnum may be applied to established head or leaf lettuce at 1.0 pint per acre after lettuce has emerged. Dual Magnum should not be applied preemergence to lettuce because of potential for severe stand thinning. There is a 50-day pre-harvest interval, so application must be made soon after lettuce emergence. This is an indemnified label, and growers assume all risk for crop injury.

MDARD also has approved a Section 24c SLN label for Gramoxone Inteon for postemergence directed and shielded application to the area between the rows of lettuce. A shielded sprayer with which the nozzles are completely covered during the application is required so that Gramoxone Inteon does not contact the lettuce plants. Gramoxone Inteon must be applied at a rate of 1.5 pints per acre two to three weeks after seeding, in a minimum total spray mix of 40 gallons per acre. Gramoxone Inteon will kill most small annual weeds upon contact. Weeds remaining in the rows and alleys should be removed by hand or cultivation. This label is in effect for five years through 2016.

The label for Kerb for preemergence application on head lettuce on mineral or muck soil remains in effect. Prefar is also an effective preemergence herbicide for lettuce on mineral soil. The use of Dual Magnum and Gramoxone Inteon for weed control will help growers on muck soil produce Romaine and other leaf-type lettuce profitably. We hope to have the new Kerb label for leaf lettuce approved by 2014.

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