Sinalbin, the same compound that gives white mustard its pungent flavor, could also prove useful in fighting weeds.

Agricultural Research Service studies suggest sinalbin and other compounds that are released into soil when white mustard seed meals are applied can kill or suppress some weedy grasses and annual broadleaf weeds.     

Agronomist Rick Boydston, with the ARS Vegetable and Forage Crops Research Unit in Prosser, Wash., is conducting the studies with plant physiologist Steven Vaughn in Peoria, Ill.

They evaluated the effects of three mustard seed application rates—1/2 ton, 1 ton and 2 tons per acre. Of the three, the 1-ton and 2-ton rates worked best in peppermint, reducing barnyard grass, green foxtail, common lambsquarters, henbit and redroot pigweed populations by 90 percent several weeks after application.

Although young peppermint plants sustained minor damage from the treatment early on, they recovered and resumed their normal growth.

Onions weren't so lucky. Regardless of the application rate, the treatment severely damaged the bulb crop when applied before emergence or before the onions produced two true leaves. Applications at the two-leaf stage or later were more promising.

In adedition to white mustard, the researchers also evaluated the weed-control effects of field pennycress seed meal and dried distiller grains, derived from corn ethanol production. Like white mustard, field pennycress also has potential as a biodiesel crop. It and distiller grains were less effective than white mustard at controlling weeds.

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