Mar 23, 2017
Dual Magnum labeled for Michigan summer squash, strawberry

Syngenta Crop Protection has added summer squash and strawberry to the Dual Magnum (S-metolachlor) Michigan 24c SLN label. Dual Magnum is a pre-emergence herbicide that provides suppression of several annual grasses and broadleaves, and also suppresses yellow nutsedge. Dual Magnum is widely used in field crop production and is labeled for use on many fruit, vegetable and ornamental crops. Dual Magnum is a very long chain fatty acid synthesis inhibitor (Group 15 K3), which prevents seed embryos from expanding in susceptible weeds. It does not have post-emergence activity on established weeds.

In summer squash, Dual Magnum may be applied broadcast to soil before seeding or transplanting, or after squash emergence when the plants have at least one true leaf. If the summer squash is grown on plastic, Dual Magnum should be applied to soil before laying the plastic. It also may be applied to row middles after laying plastic. The use rate is 0.67 – 1.33 pints per acre. Use the lower rate on coarse, sandy soils. There is a 30-day pre-harvest interval.

In annual and perennial strawberries, Dual Magnum may be applied before or after transplanting, pre-emergence to dormant strawberry before emergence in the spring, post-emergence after spring emergence, post-emergence to row middles, or after renovation. Dual Magnum may be applied before laying plastic or after laying plastic to row middles. The application rate is 0.67 – 1.33 pints per acre. Use the lower rate on coarse soils. There is a 30-day pre-harvest interval.

Dual Magnum should not be incorporated; it should be applied to damp soil or followed by 0.25 inch of rain or irrigation for activation. Dual Magnum suppresses germination of most annual grasses, including barnyardgrass, large crabgrass, fall panicum and the foxtails. It provides fair control of annual bluegrass and field sandbur. Among broadleaves, it controls galinsoga, eastern black nightshade, spotted spurge, amaranths and pigweeds. It has good activity against yellow nutsedge. At the rates used, Dual Magnum provides four to five weeks of weed control. It does not provide season-long control of any weeds, so other herbicides usually are needed during the season.

To access the Dual Magnum 24c label, go to FarmAssist, click on Products and then Indemnified Labels. Select the state (Michigan), product (Dual Magnum) and crop. You must agree to the conditions of the indemnified label. After clicking “I accept,” the label may be printed. This is the same process for all of the Syngenta indemnified labels, and all crops on the Michigan Dual Magnum label will be printed.

Dual Magnum is another effective tool for Michigan growers of summer squash and strawberry. If used along with other herbicides, it should improve production of these and other registered crops.

For more information, visit

Bernard Zandstra, Michigan State University

Source: Michigan State University Extension

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