NDSU Crop and Pest Report
Weeds


ISSUE 3  May 15, 2003

 

PEST REPORT #2 CORRECTION:

Everest is an Arvesta product and Arvesta is developing proprietary products and markets generic products.

 

CROP ROTATION RESTRICTIONS IN 2003 ND WEED GUIDE CLARIFIED

The crop rotations restrictions for Everest in the ND Weed Guide show next cropping season (NCS) for several crops including sunflower. There are no mention of several crops that are grown in ND on the Everest label and no restrictions for these crops are given, including sunflower. NDSU research indicate, with limited data points, no injury to sunflower planted the year following application of Everest. Technical information of physical characteristics of the active ingredient show the half life of flucarbazone (ai in Everest) is 17 days so the likelihood of injury is low. The rotational interval for crops on the label must be followed.

Stinger in the 2003 ND Weed Control Guide shows a 10.5 month crop rotation restriction for canola and an 18 month rotation restriction to flax. Dow is in the process of moving canola and flax to the 5 month rotational crop category now that EPA tolerances have been set for these crops. This will also apply to Curtail/M. The revised labels were submitted to EPA about the end of February, so we Dow should be receiving the new labels soon. Because the tolerance has been set rotation the next year to flax and canola is permitted. Curtail M which contain clopyralid has a federal label on flax.

Acetochlor (ai of Harness, Surpass, DoublePlay, others) is a non-residual corn herbicide. The label restricts crops that can be planted the following year after application to corn, soybean, and wheat. Syngenta and Dow has been working with EPA to reduce the rotational interval for many of these crops but because of the high priority of other projects and backlog in their workload it be sometime before label changes are made. The current label restrictions must be followed until the changed occur.

 

CANADA THISTLE

Reports in the regions show slow Canada thistle emergence. Researchers in Wisconsin dug up some roots at an experiment station and found the crown area of nearly all plants died during the winter. They found the main vertical root was dead for 4 to 8 inches below the surface which may explain lack of or latter emergence. They also found an enormous crop of new shoots emerging from lateral roots 6 or more inches below the soil surface. Summary: Weak thistle plants may have died during the winter and others may be slowed or initially out competed by vigorous growing crops. The lack of snow and periods of cold temperatures during the winter may have killed some Canada thistle roots but there is enough underground root stock to compensate so look out for another year of Canada thistle year. The 2000 ND Weed Survey shows a 3X increase in the density of Canada thistle infestations across the state. Donít slack on control. More about the weed survey to come in future Pest Report issues.

 

ACTIVATION OF SOIL-APPLIED HERBICIDES AFTER THE RAIN

It is true that soil-applied herbicides applied prior to the recent rains will work well. If the intended herbicide was not applied before but will be applied after the soil drys, will it require rain for activation? Yes. Rain is required to physically move the herbicide into the soil and to the zone where weed seeds germinated. It may not require as much water to activate the herbicide because of good soil moisture it will require some.

 

EARLY SPRING WEEDS OF NO-TILL CROP PRODUCTION

Various winter annual, biennial and perennial weeds are usually present in no-till fields in sufficient numbers in early spring to warrant a burndown herbicide treatment before planting a summer row crop. Proper identification of these weeds is critical for selecting herbicides and determining appropriate rates of application. This publication is intended to serve as a practical reference for the identification of weeds present in no-till production systems. It includes more than 130 color photos of 45 common weeds. A four-page taxonomic key assists in identification by means of distinctive plant features. Also included are a glossary and a guide to herbicides for controlling early-spring weeds in no-till fields.  24 pages.

The University of Missouri Extension Publications is offering the Revised March 2003 version of Early Spring Weeds of No-Till Crop Production (NCR614) for $2.00 per copy (plus shipping/handling) for orders of 50 or more copies. Please mention the discounted $2.00 price when placing your order. This offer is valid until June 30, 2003.

Orders placed after your initial order or after June 30 will be offered at 20% off our regular price of $3.00 per copy at $2.40 per copy.

Early Spring Weeds of No-Till Crop Production

http://www.muextension.missouri.edu/explore/images/coverncr614.jpg

PDF complete document

http://www.muextension.missouri.edu/explorepdf/regpubs/NCR614.pdf

 

WEB SITE FOR EARLY SEASON WEED IDENTIFICATION

See the following web site for from the University of Illinois for identification of early season weeds. The web site is:

http://www.ag.uiuc.edu/cespubs/pest/articles/200305e.html

 

HERBICIDE PREMIX COMPARISONS

Herbicide premixes provide growers many benefits, including fewer herbicide containers, easy mixing, flexibility in adding (spiking) extra herbicide if needed, and in many cases, a lower cost per acre than if the components were purchased separately. Knowing the active ingredients in the premixes is important and helps when choosing product to control pivotal weeds, in developing a herbicide resistant weed program, determining rotational crop restrictions, and any herbicide tolerant hybrid requirements. The weed guide contains charts on pages 83, 87, and 126 through 130 showing the components in most premix products registered. The North Dakota Herbicide Price List on pages 126-130 has been replaced with the 2003 price list which can be found on the web version of the weed guide - address is listed on the cover of the 2003 weed guide.

Richard Zollinger
NDSU Extension Weed Specialist
rzolling@ndsuext.nodak.edu


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