Preserving Weed Seeds for Science

By Don Comis
August 4, 2003

While the rest of the farm crew removes weeds, Ruth Mangum is busy planting them on the 7,000-acre Henry A. Wallace Beltsville (Maryland) Agricultural Research Center. Mangum is curator of one of the country's oldest and most extensive weed seed collections at the center, part of the Agricultural Research Service.

During the summer of 2002, Mangum planted seed from all 30 pigweed types in the collection. She irrigated the pigweed and hand-pulled other competing weeds, giving the pigweed some of the tender loving care normally reserved for farm crops. She would give them even more care, but weeds do better with less--for example, they don't need fertilizer.

The collection, now up to 290 lots of seeds, began in the 1960s. Mangum is now moving into her 24th year as weed "librarian." She "lends" seed to researchers around the country, much as a librarian lends books. Also, like a librarian, she keeps a record of what she sends. But she doesn't want the seeds returned--she wants to be able to send more from the same seed lot, if asked.

Mangum and colleague John Teasdale, at the ARS Sustainable Agricultural Systems Laboratory in Beltsville, see the collection as a key tool in helping researchers learn how to control weeds better.

On September 17, Teasdale will present a paper, co-authored by Mangum, ARS agronomist Jay Radhakrishnan and ARS soil scientist Michel Cavigelli, also with the Sustainable Agricultural Systems lab, on buried weed seeds under different farming systems--including organic farming--for a weed seed conference. Held at the University of Reading, United Kingdom, it's sponsored by the Association of Applied Biologists, in association with the European Weed Research Society.

In the meantime, Mangum hopes the farm crew forgives her for the inevitable pigweed that may escape from her fields during subsequent summers.

For more information on the weed seed collection, see the August issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.