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ISSUE 3  May 18, 2000

SPRING SPRAYER SCHOOLS AND RIGHT-OF-WAY CERTIFICATION

    The North Dakota Weed Control Association has scheduled training sessions for non-cropland weed control personnel at two locations this year. Topics to be covered include noxious and invasive weed identification, herbicide drift avoidance, equipment calibration, and safe use of pesticides. The Williams County Weed Board will host the first session in Williston, ND, on Monday May 22, 2000. The second session will by hosted by the Cass County Weed Board and the NDSU Plant Sciences Dept., on Thursday, May 25, 2000 in Loftsgard Hall on the campus of NDSU.

The complete agenda for both schools:

    8:45am - Registration

    9:00am - Right-of-Way Certification, Andrew Thostenson

    9:30am - New Invasive and Nasty Weeds, Rod Lym

    10:15am - Herbicide Drift Avoidance & Consequences, Vern Hoffman

    10:45am - State, National, and Global Issues, Andrew Thostenson

    11:45am - Lunch ($6)

    1:00pm - Herbicide Update, Rod Lym

    1:20pm - Equipment and Calibration, Vern Hoffman

    2:30pm - Enhancing Safety by Reading Labels Properly, Andrew Thostenson

    The spring sprayer schools serve as a brush-up course for new and returning weed control
personnel. The course offers Pesticide Certification in the Right-of-Way category and is open to
all those interested.

Rod Lym
Perennial/Noxious Weed Scientist
lym@plains.nodak.edu

 

HERBICIDE UPDATE

    Balance (isoxaflutole) at 1.25 to 2 oz WDG/A applied EPP, or PRE in corn controls most annual grasses included foxtails, wild proso millet, field sandbur, and woolly cupgrass and most annual small-seeded broadleaf weeds, including nightshade, kochia, pigweed, lambsquarters, common ragweed, wild mustard, annual smartweed, seedling dandelion, and horseweed (marestail). Balance has a mode of action different from other herbicides and can control resistant green foxtail and kochia. Balance has a unique pigment inhibition mode of action and can cause chlorosis after corn emerges under stress conditions or any condition which may inhibit corn growth. NDSU tests have shown that yellowing disappears after 3 to 5 days with no effect on subsequent growth or yield. Balance is applied at low rates. Accurate and precise application and using exact rates based on soil type, pH, and organic matter is required to insure adequate corn safety. Applying Balance at rates slightly greater than those recommended for soil type, soil pH, and organic matter can cause slight to serious corn injury. Uneven application, variable ground speed, lack of good agitation, sprayers not properly calibrated, improper incorporation and especially spray overlaps may increase corn response. Always preslurry Balance with water prior to adding to the tank. Allow time for Balance to dissolve in tank, afterward providing thorough agitation.

    Follow label instructions in application. Sprayer overlaps, uneven coverage at application, corn seeded at less than 1.5 inches deep, and applying more herbicide than allowed by soil texture, organic matter, and soil pH greater than 7.5 all greatly increase risk of corn injury. Environmental conditions that stress corn at emergence may also increase risk of injury from Balance herbicide. The label show rates to use based on soil texture and organic matter. Try to adjust rates across fields as soil texture and organic matter varies across the field.  Seed corn at least 1.5 inches deep with adequate soil covering the furrow to prevent herbicide contact on seed. DO NOT apply POST to corn or corn will die.

    Balance is labeled with most PRE herbicides. A tank-mix with atrazine and/or acetochlor controls of most annual grass and broadleaf weeds. Balance PRE can be followed by all POST herbicides labeled in corn. Balance is weak on yellow foxtail, wild oat, volunteer grain, and large-seeded broadleaf weeds like wild buckwheat, cocklebur, sunflower, giant ragweed. Balance gives no wild buckwheat control. Research indicates Balance PRE provides greater weed control than other PRE corn herbicides. Balance has shown good to excellent weed control under limited rainfall conditions. However, 0.5 to 0.75 inches of rainfall after application is required for optimum weed control. If weeds emerge after application from lack of rainfall, a rain event can activate the herbicide, cause susceptible weeds to turn white and kill emerged weeds up to 2 inches tall. Balance will give 6 to 8 weeks residual weed control after activation. See herbicide residue section for crop rotation restrictions. Precipitation and soil moisture is more critical to breakdown than other factors.

    Python (flumetsulam) at 0.8 to 1.33 oz 80WDG applied EPP, PPI, or PRE in corn and soybean will control some small-seeded broadleaf weeds like nightshade, pigweed, kochia, lambsquarters, mustards, annual smartweed, marshelder, Russian thistle, and Venice mallow. Python may also provide suppression of common ragweed. Python does not control grasses. The label for 2000 shows suppression of biennial wormwood. NDSU research is being conducted to determine efficacy of Python on biennial wormwood under differing rates and conditions. Python requires rain for activation and maximum weed control.

    Boundary (s-metolachlor + metribuzin) applied EPP, PPI, or PRE in soybean controls many annual grass and broadleaf weeds. Boundary is similar to Turbo but has different concentration of ingredients. Turbo contains metolachlor + metribuzin at 6.55 + 1.45 lb ai/ gal. Boundary contains s-metolachlor (more active version of metolachlor) + metribuzin at 6.3 + 1.5 lb ai/gal for improved weed control. Boundary has the same risks of soybean injury from metribuzin when too high a rate is used for soil
type and to soil with pH greater than 7.5. See label for other restrictions and precautions.

    Spartan (sulfentrazone) has been granted a 2000 Section 18 registration on sunflower for control of kochia and several other weeds. Apply PRE at rates of 2.67 to 5.33 lb 75DF/A according to soil type. Sunflower has exhibited good safety to Spartan on medium to fine textured soils with organic matter above 3%. Sunflower injury may occur on soil with less than 1% organic matter and on soils with pH greater than 8.0, especially on calcareous outcropping . Refer to label for use rate.
Spartan does not control grasses. A tankmix with Prowl may be used to control foxtails or a registered postemergence grass herbicide may applied after grasses emerge.

    In addition to kochia control, Spartan may also control other small-seeded broadleaf weeds, such as, annual smartweeds, Russian thistle, wild buckwheat, nightshade species, biennial wormwood, marshelder, pigweed species, and common lambsquarters. Spartan has NO perennial weed control. No weeds have become resistant to the mode of action of Spartan (PPO inhibitor) and other herbicides of the same mode of action.

    Spartan REQUIRES MOISTURE FOR ACTIVATION. Consistent control of sensitive broadleaf weeds, grass suppression, and marginally controlled weeds greatly depends on rainfall shortly after application and before weeds emerge. At least one inch of rain is required after application for optimum weed control. If no rain occurs after application, a light harrowing or rotary hoe operation may destroy emerging weed seedlings and help active the herbicide. Spartan will not control weeds once emerged.

    Follow the following crop rotation guidelines when rotating crops the year following Spartan application.

    The price of Spartan has decreased in 2000. The price of Spartan is approximately $2.50/oz and may cost from $6.50 to 13.50/A depending on rate used, program offers and discounts from bulk purchase.

Richard Zollinger
NDSU Extension Weed Specialist


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