NDSU Crop and Pest Report

ISSUE 8  June 19, 2003


As indicated in last Friday's press release, the North Dakota Department of Agriculture recently issued Special Local Needs registrations to Dow AgroSciences to allow use of Vista herbicide on wheat and barely. Unlike most SLN registrations that have a 5-year expiration, these registrations were only issued to fill market supply needs this year for Starane.

Since the press release, I have had several phone calls from dealers and growers with questions on the expiration date. Concerns were raised about situations in which people might have left-over Vista this year, and whether the product could be used on wheat and barley next year.

Both supplemental labels for Vista contain the following statement: "Expiration date: This label expires and must not be distributed or used in accordance with this SLN registration after December 31, 2003."

These labels are only to be used this year to fill a short-term supply need. Unless the manufacturer requests and consents to extending these SLN registrations beyond December 31, 2003, it will be illegal to use Vista on wheat and barley next year. Therefore, I urge wheat and barely growers to only purchase enough Vista for use this year since any left-over product

will only be allowed to be used according to the label directions on the full product labeling.

Jim Gray
Pesticide Registration Coordinator
ND Department of Agriculture



More calls and inquiries are being made about downy brome control. Few option are available and the most wild oat products do not control downy brome. Maverick is registered for control but leaves a long residue in the soil for several years. Control is best with Maverick when applied in the fall. Other products are in development.

A good resource on downy brome biology and management is a 4-page bulletin available from the University of Nebraska available at :




Field horsetail is a prehistoric plant reproducing by spores instead of seeds. Horsetail becomes a problem in field conditions, especially under reduced tillage. Prolonged cool weather favors horsetail growth .

Tillage is one of the most effective options for control. Few herbicides, including glyphosate give adequate control. Some reports have indicated MCPA and Beacon have some activity but does not kill roots of the perennial beast.

Options? Cultivation and aggressive tillage in the infested areas after harvest.

More information on the biology and management of field horsetail can be found in an agronomy advice item at the Univ of WI Weed Sci. Web page site:




Ammonia + water:

2,4-D, Accent, Accent Gold, Ally/XP, Amber, Amplify, Assure II, Basis, Basis Gold, Cimarron/Max, Classic, dicamba, Escort, Exceed, Expert, Finesse, FirstRate, Harmony GT, Glean, Option, Peak, Permit, Python, Resolve, Steadfast, Stinger.

Ammonia + Simple Green at 1:1 ratio + water:

Callisto, Lumax.

Kerosene or diesel fuel followed by ammonia + water:

2,4-D ester

Ammonia or commercial tank cleaner + water:

Action, Basagran, Beacon, Buctril + Atra, bromoxynil, Callisto, Classic, Cobra, Dual/II/Magnum, Extreme, Fusilade DX, Fusion, Gauntlet, Gramoxone, Harness, Harmony Extra/XP, Hornet WDG, Lasso, Lightning, Moxy, Moxynil, Northstar, Prowl, Pursuit, Pursuit Plus, Raptor, Reflex, Resource, Select, Surpass, Treflan, trifluralin, and Ultra Blazer.

Water: Command, Extreme, glyphosate, Lightning, Raptor.

Detergent + water: Aim, Atrazine, and Sencor.

Commercial tank cleaner + water:

Flexstar, Liberty, Liberty ATZ, Shotgun, and Touchdown

Detergent or commercial tank cleaner + water:

Celebrity Plus, Clarity, Distinct, Marksman, Poast Plus, Turbo, Ultra Blazer, Yukon.

Ammonia, commercial tank cleaner, or detergent + water: Poast.

Baking soda (1 to 2 lb/100 gal water): Engame



Trace amount of herbicide left in the sprayer after treating crop may cause injury in sequential application. Some herbicides have greater potential than others but advise caution to those that think that gallon or two left in the bottom of the tank will not hurt anything. Tank residues are unlikely to amount to more than 1% of the original rate applied to the target crop. For instance, 1% residues of herbicides applied in pints, quarts or pounds per acre of the original rate would have minimal effect on crops. The herbicides that does need to be scrupulously removed from the sprayer are those capable of causing damage at low concentrations. These are the all ALS herbicide mode of action products (SUs, Imi, and TPS) and hormone-type herbicides such as 2,4-D, MCPA, dicamba, and Tordon. Even 1% of the recommended rate of these herbicides will definitely cause damage to many broadleaf crops. The damage to legumes caused by trace amounts of ALS herbicides in the spray is greater in the presence of grass-selective herbicides. The xylene in the grass-selective formulation probably acts as a spraying oil and increases the uptake of the herbicides.

The timetable of the season may require the POST grass herbicides to be applied after the ALS herbicides have been applied to small grains where such damage is a real possibility. Where possible, a selective grass herbicide such as Puma should be sprayed through the boom onto wheat before moving onto the broadleaf crops. Immediately after using either ALS or hormone herbicides, the sprayer should be thoroughly cleaned using the appropriate method.

Herbicides difficult to remove from sprayers are thought to be attaching to residues remaining from spray solutions that deposit in a sprayer. The herbicide must be desorbed from the residue or the residue removed in a cleaning process so the herbicide can be removed from the sprayer. Sprayer cleanout procedures are given on many herbicide labels and the procedure on the label should be followed for specific herbicides.

The following procedure illustrating a thorough sprayer cleanup procedure is effective for most herbicides:

Step 1. Drain tank and thoroughly rinse interior surfaces of tank with clean water. Spray rinse water through the spray boom. Sufficient rinse water should be used for 5 minutes or more of spraying through the boom.

Step 2. Fill the sprayer tank with clean water and add a cleaning solution (many labels provide recommended cleaning solutions). Fill the boom, hoses, and nozzles and allow the agitator to operate for 15 minutes.

Step 3. Allow the sprayer to sit for 8 hours while full of cleaning solution so the herbicide can be fully desorbed from the residues inside the sprayer.

Step 4. Spray the cleaning solution through the booms.

Step 5. Clean nozzles, screens, and filters. Rinse the sprayer to remove cleaning solution and spray rinsate through the booms.

Common types of cleaning solutions are chlorine bleach, ammonia, and commercially formulated tank cleaners. Chlorine lowers the pH of the solution which speeds the degradation of some herbicides. Ammonia increases the pH of the solution which increases the solubility of SUs and weak acid herbicides. Commercially formulated tank cleaners generally raise pH and act as detergents to remove herbicides. Read herbicide label for recommended tank cleaning solutions and procedures.

WARNING: Never mix chlorine bleach and ammonia as a dangerous and irritating gas will be released.

Sprayers should be cleaned as soon as possible after use to prevent the deposit of dried spray residues. A sprayer should not remain empty overnight without cleaning; fill the tank with water to prevent dried spray deposits from forming. A clean sprayer is essential to prevent damage to susceptible crops from herbicide contamination.

Richard Zollinger
NDSU Extension Weed Specialist

NDSU Crop and Pest ReportTop of PageTable of ContentsPrevious PageNext page