ISSUE 8   July 1, 2010

CONTROLLING ESTABLISHED ALFALFA

From time to time I get phone calls about the best herbicides to control alfalfa. It appears data is limited but below is a summary from a study conducted at NDSU and several compiled studies from SDSU. Most application were made to 6 to 10 inch alfalfa .

Control of established alfalfa (1993) - Rich Zollinger - NDSU. Treatments were applied to 8 inch alfalfa on May 11, 1993

Summary of SDSU data: (Spring applications). Multiple numbers are from separate studies. Numbers are from evaluations made 1 to 2 months after application and does NOT reflect final alfalfa control due to regrowth that might possibly occur.

Summary of SDSU data (Fall applications and evaluations made spring the next year).

I have received several calls of crop damage from drift, tank contamination, and carryover of residual herbicides. Folks have asked where the plant tissue or water can be sent to have it tested for herbicide concentration.

Page 111 in the 2010 ND Weed Control Guide lists several labs to choose from. Contact the labs before sending any material to make sure they can analyze the chemical in question and proper method to send the material. Here is an abbreviated list from the weed guide:

Laboratories That Analyze For Pesticide Residue in soil, water, and plant samples. For links to labs in each state see AGLABS website: http://aglabs.sdstate.org

A & L Great Lakes Lab
3505 Conestoga Drive, Fort Wayne, IN 46808
(219) 483-4759, http://www.algreatlakes.com

Agvise Laboratories
Northwood, ND
(701) 587-6010, johntlee@polarcomm.com

Analytical Laboratory
McCall Hall, PO Box 173620
Montana State University, Bozeman, MT 59717
(406) 994-3383, Heidi Hickes
Developed the most sensitive test available for Oust.

Harris Laboratories
621 Rose Street, P.O. Box 80837, Lincoln, NE 68501
(402) 476-2811, http://www.mdsharris.com

Hazelton Environmental Services
525 Science Drive, Madison, WI 53711
(608) 232-3300

Midwest Laboratories
13611 B Street, Omaha, NE 68144
(402) 334-7770, http://www.midwestlabs.com

Minnesota Valley Testing Laboratories, Inc.,
326 Center Street, New Ulm, MN 56073
(507) 354-8517, (800) 782-3557

Minnesota Valley Testing Laboratories, Inc.,
1411 South 12th Street, Bismarck, ND 58504
(701) 258-9720, (800) 782-3557

Olson Biochem Labs, Duane Matthees
South Dakota State University
Office: 134 ASC, Brookings, SD 57007-1217
Samples: 152 ASC, Brookings, SD 57007-1217
Office: (605) 688-6160, Lab: (605) 688-6171

duane.matthees@sdstate.edu, http://anserv.sdstate.edu

Professional Service Industries
4820 West 15th Street, Lawrence, KS 66049
(800) 548-7901

Several people have called asking for the "secret" recipe for controlling elm and other woody tree species in cropland from shelterbelt and tree plantings. Unfortunately, there is no secret recipe. Tree seedlings are perennial and, as such, are affected most by the herbicides we use to control perennial species - 2,4-D, dicamba, Tordon, glyphosate. Volunteer trees are very difficult to control relying only on chemical control and without tillage. The trees would be even be more difficult to control in non-Roundup Ready broadleaf crops (like dry edible beans and sunflower) where systemic, growth regulator herbicides cannot be used. Page 66 in the 2010 ND Weed Guide shows control options in pasture, rangeland, and noncopland. With the exception of the GR herbicides listed above, herbicide are mostly ineffective. Glyphosate is not effective after tree seedlings get much size (become perennial).

Rich Zollinger
NDSU Extension Weed Specialist
r.zollinger@ndsu.edu