NDSU Crop and Pest Report

ISSUE 6  June 6, 2002



A living weed exhibit is available for public viewing at the NDSU Carrington Research Extension Center. Before weeds can be effectively managed, they must be properly identified. The objective of the arboretum is to be a reference for farmers, landowners, gardeners, and other persons to aid in weed identification and management. The exhibit contains over 60 weeds that are labeled by common name. The weeds are arranged in groups as annual broadleaves, annual grasses, winter annuals, biennials, perennials, and North Dakota noxious weeds. Individuals or groups may informally visit the arboretum anytime during the growing season. If a formal tour or training session is desired, please contact the Carrington Center at 701-652-2951.

Gregory Endres
NDSU Extension Service Area Agronomist
Carrington R&E Center



Steadfast (DuPont)
Mode of action: ALS inhibitor
a.i.: nicosulfuron + rimsulfuron
Crops: Corn.

Comments: DuPont allows use on corn greater than 77 CRM. However, consult the corn hybrid producer for any herbicide precautions. For the northern corn-growing region, Steadfast, Accent Gold, and Basis Gold may be applied to corn no more than 12 inches tall or no more than 5 collar, which ever is the most restrictive. Follow crop rotation restrictions.



Some people have asked how to kill thin/poor stands of Roundup Ready corn prior to replanting Roundup Ready corn. The logical choice would one of the POST grass herbicides, such as, Poast, Assure II, or Select. Be careful!

The half life of these products are given below:

Assure II: 60 days
Fusilade DX: 15 days
Poast: 5 days
Select: 3 days

Of those listed above it appears that Select would have the least risk of corn injury. Remember that only half of the product is broken down after the number of days indicated and then it takes another period of the same time to break down half of the product that is left. For example, Select applied at 4 fl oz/A after 3 days would be 2 fl oz and after 6 days would 1 fl oz/A and after 9 days would be 0.5 fl oz/A, and so on.

Below are issues to consider.

1.Follow the label - some POST grass labels do not allow corn replant for 30 days after application.

2. Contact herbicides like paraquat (Gramoxone Extra) will act similar to a frost and only burn off emerged leaves. The growing point of corn stays below ground until the 5-leaf stage. Spraying before the 5-leaf stage will not kill the growing point.

3. Plant Liberty Link corn. Then apply Liberty after the first planting of corn reaches the 5-leaf stage and the growing point moves above ground.

4. Select at 2 fl oz/A rather then 4 fl oz/A may be sufficient to kill small corn. The reduced herbicide rate will decrease likelihood of injury to emerging corn plants.

5. Risk of injury is reduced when top soil is dry and there is NO movement into the soil. Risk of injury greatly increases when rainfall occurs after application by moving the herbicide into the root zone.

6. Poast and Select are degraded rapidly by sunlight. This is independent of the half-life from microbial breakdown. Two days of bright, intense sun after application with no movement into the soil can degrade most of the product.



Paragraph A8 on page 72-73 of the ND Weed Control Guide has been updated on information for sprayer clean out.

Ammonia + water:  2,4-D, Accent, Accent Gold, Ally, Amber, Amplify, Assure II, Basis, Basis Gold, Classic, dicamba, Exceed, Expert, Finesse, FirstRate, glyphosate, Harmony GT, Glean, Option, Peak, Permit, Python, Resolve, Steadfast, Stinger.

Kerosene or diesel fuel followed by ammonia + water:  2,4-D ester

Ammonia or commercial tank cleaner + water:  Action, Basagran, Beacon, Bladex, Buctril + Atra, bromoxynil, Callisto, Classic, Cobra, Contour, Dual/II/Magnum, Extreme, Fusilade DX, Fusion, Gauntlet, Gramoxone, Harness, Harmony Extra, Hornet WDG, Lasso, Lightning, Moxy, Moxynil, Northstar, Passport, Prowl, Pursuit, Pursuit, Plus, Raptor, Reflex, Resource, Scepter, Select, Squadron, Status, Steel, Surpass, Treflan, trifluralin, and Ultra Blazer.

Water: Command and glyphosate.

Detergent + water: Aim, Atrazine and Sencor.

Commercial tank cleaner + water: Flexstar, Fusion, Liberty, Liberty ATZ, Shotgun, and Touchdown

Detergent or commercial tank cleaner + water:  Callisto, 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

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 some 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