Collecting Lambsquarters Seed for Glyphosate Testing

Chris Boerboom and Dave Stoltenberg, Agronomy Dept.

In the June 22 issue of the Crop Manager, we wrote an article requesting that you keep an eye open for common lambsquarters that is not being controlled by glyphosate.  If there is no readily apparent reason for the lambsquarters to escape control, the potential exists that the lambsquarters might have a low level of resistance.  We want to test seedlings from these plants this winter to determine if any shift in glyphosate sensitivity is occurring in Wisconsin.

If you have a field with lambsquarters escapes, please consider if these lambsquarters are a good candidate for testing.  Review the previous article (click this link if you are on-line) for points to consider when trying to determine if the escapes might be from application or environmental issues or resistance.

If the lambsquarters does not have any logical reason for escaping, we would like a seed sample for testing.  Unfortunately, gathering a lambsquarters seed sample is not as easy as grabbing and shelling an ear of corn.  Also, getting enough lambsquarters to germinate is also not easy, so we need a fair amount of seed to plant for testing.  We recommend these guidelines for collecting and submitting lambsquarters seed.

Needed:  1/4 cup of mature seed (black or brown)

Suggested collection method

1. Wait until black seeds develop in the seedheads.

2. Clip the seedheads of many plants and place in a couple of grocery bags, leave bags open.

3. Leave bags in the shed or garage for a week to air dry.

4. Rub the dry seedheads to knock out the seed.

5. Collect the seed in an envelope or small paper bag. Don’t worry about chaff mixed with the seed.  If there is a lot of chaff, try to collect about 1/2 cup of seed and chaff.

6. Mail the seed to Dave Stoltenberg at the address below. 

7. Please include this site information.

Information:

Field: (check one)   corn ____     soybean ____

Glyphosate rate(s):  __________________

Field location

Township: _______________________

County:  _________________________

Contact information

Name: _____________________________

Phone or email: _____________________

Mail to:

Dave Stoltenberg
Agronomy Dept.
1575 Linden Drive
Madison, WI 53706