As growers prepare for respray of full season soybeans, and double crop soybeans are growing in the ground, the Delaware Soybean Board reminds growers to use responsible management techniques to control Palmer amaranth this growing season. The most competitive and aggressive pigweed species, season-long competition by Palmer amaranth at 2.5 plants per foot of row can reduce soybean yield by as much as 79%.

Effectively controlling Palmer amaranth in soybeans often requires applying postemergence herbicides, three to four weeks after planting. At that time, the soybean canopy may still be a few weeks away from closure (leaves touching between the rows to block sunlight and stop additional seedling emergence). As a result, postemergence applications need to include an additional residual herbicide to provide control until the soybeans form a tight canopy.

However, due to weather, equipment issues, timing, or desire to reduce the number of applications, fields infested with Palmer amaranth are not always treated in a timely manner. Over the past few years, the Delaware Soybean Board has funded research completed by Mark VanGessel, University of Delaware Cooperative Extension Weed Specialist, in order to provide advice and suggestions for situations with larger plants. A factsheet containing results of this research were sent to Delaware soybean growers earlier this spring.

“The Delaware Soybean Board is pleased to be able to provide valuable insights into managing this noxious weed,” says Cory Atkins, Chair of the Delaware Soybean Board. “By sharing the results of this research, we aim to reduce yield losses for farmers and build a stronger soybean industry.”

The full version of the factsheet may be found by clicking here.

Delaware farmers plant about 160,000 acres of soybeans annually, producing over seven million bushels of beans and generating approximately $60 million in value to the state. The Delaware Soybean Board consists of nine farmer-directors and the Secretary of Agriculture. Funded through a one-half of one percent assessment on the net market value of soybeans at their first point of sale, the checkoff works with partners in the value chain to identify and capture opportunities that increase farmer profit potential.


For information, contact:

Danielle Bauer Farace
Executive Director
Delaware Soybean Board