North Dakota State University
North Dakota Agricultural Experiment Station
Carrington Research Extension Center

Carrington Research Extension Center Ag Alerts

Ag Alerts for the week of September 10:


Canada thistle control nine to eleven months after herbicide application in September.

                        Herbicide                  Canada 
----------------------------------------------     thistle
Trade name         Rate             Cost           control*   
                   pt/A         ----$/A----         --%--

2,4-D               2            3.25-4.00        39-48 (2)
                    4            6.50-8.00        32-51 (2)
Banvel              2                23.75        52-91 (4)
Roundup             2           9.25-13.25        53-92 (4) 
                    3          14.00-20.00        75-96 (2)
 + 2,4-D           1.25 + 1     7.50-10.25        41-72 (2)
                    2 + 1      11.00-15.25        56-94 (2)
Fallowmaster       2.75               6.25        19-88 (3)
Curtail             2                 9.50        46-75 (5) 
                    4                19.00        53-91 (3)
*Visual evaluation of control.  Number in 
parenthesis indicate number of trials that 
included treatment.  Trial location and year 
1. Brookings, SD.  1991.
2. Deuel County, SD.  1995.
3. Fargo, ND.  1997.
4. Carrington, ND.  1998.
5. Cathay, ND.  1998.
6. Flaxton, ND.  1998.


The objective of a nightshade management program is to avoid seed introduction and eliminate seed production. Nightshade control after crop harvest is important to stop late-season seed production. Fall control options include tillage, herbicides, or a combination. Post-harvest tillage will destroy existing nightshade plants, but complete prevention of seed production is not likely. Seed production likely occurred prior to the tillage operation and may occur after due to plant escapes or late-emerging plants. Mature seed present during the tillage operation likely will stick to tillage implements and subsequently may be spread to other areas of the farm.

Herbicides are another late-season nightshade control option. Trials conducted in South Dakota in 1993 and North Dakota in 1996 to determine if herbicides are effective in rapidly controlling nightshade plants to cease further seed development in the fall. In both trials, herbicide treatments that included paraquat (e.g. Gramoxone Extra) were effective in quickly controlling nightshade plants (75 to 99 percent control) and stopping seed development. In addition to paraquat, bromoxynil (e.g. Buctril) and Liberty provided 88 to 98 percent nightshade control in the ND trial. As expected, the herbicide treatments did not completely destroy existing berries and seed.

Integrated nightshade management tools must be used throughout the year. The tools include crop rotation, use of clean crop seed, equipment sanitation, as well as tillage and herbicides. Refer to the NDSU Extension Service circular W-253 "ND Weed Control Guide" for details on nightshade identification, biology, and management.

Greg Endres, Area Extension Specialist/Cropping Systems, Email:
1998 Ag Alert Archive * Carrington R&E Center Home Page * NDSU Agriculture