Renewed labels for onions and green onions in Michigan

The United States Environmental Protection Agency (EPA) and the Michigan Department of Agriculture and Rural Development (MDARD) have approved two labels for Michigan onion growers. Both labels are Special Local needs (24c) labels for the state of Michigan.

Starane Ultra is labeled for postemergence control of broadleaf weeds and volunteer potatoes in dry bulb onions. This is a renewal of a previous 24c label which expired in 2018. Application of 0.35 pint per acre Starane Ultra may be made over the top of onions at the 2-6 leaf stage. After the 6-leaf stage, Starane Ultra may be applied as a directed spray with drop nozzles to areas between the rows. A second application may be made 10-14 days after the first application. Starane is effective in controlling volunteer potatoes, and two applications may be needed to obtain complete control. It is effective against several annual broadleaf weeds also.

Starane Ultra may injure onions and reduce yields if applied when onions are under stress from weather or excessive weed pressure. Do not apply with other postemergence herbicides. Do not apply within 42 days of harvest. The label expires July 15, 2023.

Prowl H2O may be used for preemergence weed control in green onions grown on muck soil and on mineral soil with more than 5 percent organic matter. All crops in the green onion subgroup may be treated with Prowl H2O, including chives, leeks, spring onions, scallions, Japanese bunching onions, green shallots and green eschalots. Prowl H2O may be applied at 3-4 pints per acre (1.425-1.9 pounds active ingredient) as a broadcast preemergence spray after seeding the green onions. Use the lower rate on soils with less than 10 percent organic matter. Do not apply within 30 days of harvest. The label expires April 16, 2024.

Prowl H2O controls most annual broadleaf weeds and annual grasses. It provides poor control of weeds in the mustard and aster families. Mustard weeds include yellow rocket, shepherdspurse, Virginia pepperweed and wild radish. Aster weeds are common ragweed, common groundsel, dandelion, horseweed, mayweed, pineappleweed, sowthistle and burdock. Prowl H2O is also weak against ladysthumb. It provides good control of common purslane and common lambsquarters.

These labels can be accessed at CDMS.

– Bernard Zandstra, Michigan State University Extension, Department of Horticulture