Controlling weeds in edible soybeans in Michigan

Weed control is a major concern for the new crop edamame, also known as edible soybean.

Edamame, or edible soybean, is growing in popularity as a vegetable crop. It has been popular in the Orient for thousands of years and only recently has mainstream America discovered its uses and health benefits. Edamame is high in fiber and protein, and moderate in unsaturated vegetable oils. Edamame may be used as a fresh vegetable, for growing bean sprouts, or as a cooked and salted snack similar to raw and cooked peanuts. A convenient method of preparation is boiling the pods in salt water and then opening the pods to remove and eat the seed similar to eating peanuts in the shell. It is a great TV snack.

Although edamame is the same species (Glycine max) as field crop soybean, it requires separate pesticide registrations for use as a fresh vegetable. Michigan State University Extension, chemical companies and IR-4 have cooperated to obtain several preemergent herbicide labels for edamame, and other herbicide registrations should be approved in the future.

Lorox (linuron) may be applied after seeding edamame at 1-2 pounds product (0.5-1 pounds ai) per acre. In no-till production, it may be applied to soil up to 30 days before planting edamame. Lorox controls many broadleaves and grasses for five to six weeks. Do not apply Lorox to edamame after crop emergence.

Dual Magnum (s-metolachlor) may be applied to edamame either pre-plant surface, pre-plant incorporated or preemergence after seeding. Use 1-2 pints per acre (0.95-1.9 pounds ai); use the lower rates on lighter soils with less than 3 percent organic matter. The high rate should be used on clay soils with greater than 3 percent organic matter.

Reflex (fomesafen) may be applied to edamame pre-plant surface or preemergence after seeding. The use rate is 1 pint per acre (0.25 pounds ai). Reflex may also be applied post-emergence to edamame with at least one expanded trifoliate leaf for broadleaf weed control. One pint is also the maximum use rate for the year and Reflex should not be applied to the same soil more than once in two years. The preharvest interval is 30 days.

Growers may want to try a small planting of edamame to learn how it grows and find markets. It is an exciting potential crop for Michigan growers.

Dr. Zandstra’s work is funded in part by MSU’s AgBioResearch.

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