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ISSUE 16   AUGUST 26, 1999

 

PLAN NOW FOR NDSU WIDE WORLD OF WEEDS WORKSHOP - 2000

    The NDSU Wide World of Weeds Workshop will be held January 25, 2000 (unless Y2K dictates otherwise) at the Ramada Plaza Suites and Conference Center, Fargo, ND. We are still working out the details but some topics that will be covered are:

1. The Easy and Fast Method to get Pesticides Registered on Minor Crops/IR-4
2. Invasive Weed Outlook
3. Applicator Technology - Effect of Application Speed, Spray Volume, Nozzle Types, Reduced
    Herbicide Rates, and Adjuvants on Herbicide Performance.
4. Herbicide Resistance - The Story Never Told
5. Troublesome Weeds in Beans and Row Crops - What’s ND Next Unmerciless Weed?

    Applicants will be able to attend a general session and three of the five topics at concurrent sessions offered during the day. CCA credits will be given (don’t come if that’s all your interested in) , registration price will be reasonable, the latest NDSU Weed Research book will be handed out, plus the greatest publication available (2000 ND Weed Control Guide) and new weed and herbicide bulletins will be given, good food will be served, and a chance to ask the pro’s those hard questions.

    Several new extension and weed researchers have joined the Weeds group at NDSU and will be presenting information on their expertise.

    Contact Scott Fitterer at sfittere@ndsuext.nodak.edu to be included in the mailing list for a registration application form.


DOES NORTH DAKOTA HAVE BLACK NIGHTSHADE OR EASTERN BLACK NIGHTSHADE?

    A recent Weed Technology Journal article (13:151-156) studied response of Matrix to hairy nightshade, black nightshade and eastern black nightshade. Matrix is a sulfonylurea herbicide registered for use in potato and is a component in some premixes used in corn.

    Eastern black nightshade was found sensitive (>95% injury), hairy nightshade was moderately sensitive (50 to 99% injury), and eastern black nightshade was found tolerant to Matrix. The study found that differences in uptake and translocation account for differential sensitivity to Matrix.

    Why is this significant? Dr. Richard Greenland, Research Agronomist at the Oakes Experiment Station has observed that, what he thought was eastern black nightshade was not controlled after application of Matrix. After examining plants for identification, he concluded that the farm has a healthy population of black nightshade. This journal article seems to substantiate that North Dakota has both black and eastern black nightshade. The article also reported a reference that an eastern black nightshade sample from Minnesota was found tolerant to eight herbicides. The sample was probably black nightshade.

    For simplicity, and because until now it was thought there was no difference in control, we (scientists) have lumped both nightshades together and just called both types eastern black nightshade. Another reason for not separating them is difficulty in identification by using morphological differences until plants are flowering and forming berries. Both plants look similar at the seedling and vegetative stages. The inflorescence (fruiting structures) of black nightshade is racemose (similar to grapes) and the inflorescence of eastern black nightshade is umbellate (like an umbrella where each stem of a berry connects at a common point). Page 575 of Weeds of the West gives a good picture of the racemose inflorescence of black nightshade and page 162 of Weeds of the North Central States shows a good picture of the umbellate inflorescence of eastern black nightshade.

    In conclusion, if Matrix is used for nightshade control and erratic control result correctly identify the nightshade species because black nightshade has inherent tolerance to Matrix herbicide. Also, remember to spray early because nightshade weeds become more tolerant to Matrix as they increase in size.

 

HI-DEP POSTEMERGENCE BROADLEAF HERBICIDE

    Several questions have been asked about HI-DEP herbicide. HI-DEP is an amine formulation containing: 33.2% Dimethylamine salt of 2,4-D acid and 16.3% Diethanolamine salt of 2,4-D.

    In other words, HI-DEP contains 2,4-D and 2,4-D works like 2,4-D no matter under what name you call it.

    Most 2,4-D amine formulations contain the "methyl" form. The "ethyl" form is more expensive to produce and has not been utilized as much. The formulation also contains an additive which enhances penetration into the plant. The additive has non-evaporative qualities (antifreeze) which helps keep the herbicide droplet soluble or "wet" and this in turn would increase uptake and absorption into the plant.

    Some research shows that the "ethyl" amine form may be slightly more effective on hard to control perennials such as Canada thistle, field bindweed, milkweed, and some annual broadleaf species.

    Research at North Dakota State University show that leafy spurge control is slightly better than other amine formulations during dry summers similar to 1988 and 1989. However, in years with moderate or good precipitation there is no difference.

    Another benefit of HI-DEP is that it can be applied through aerial application at 0.5 gallon per acre. This means in many cases that no dilution with water would have to be made and pure product could be applied. To benefit from use of HI-DEP carrier volume should be less than 10 gpa. HI-DEP has the crop tolerance and low drift advantages of an amine but the performance of the herbicide may be lower than Lo Vol ester formulations.

    HI-DEP is more expensive than 2,4-D amine so this may be an additional factor to consider along with potential increase in weed control. Research and experience does not warrant application of HI-DEP as giving superior performance and control as compared to 2,4-D.

    In situations where Lo Vol ester formulations can be used, weed control will be as good or better than HI-DEP. For control of annual weeds in field crops in particular, conventional amine or ester would be a better economical choice. HI-DEP can applied with Tordon or Banvel to broaden the spectrum of control.


TRANSFER OF HERBICIDE RESISTANCE FROM ONE
SPECIES OF AMARANTH (PIGWEED) TO ANOTHER.

    The pigweed or amaranth complex of weed species contain several species of plants. A study was conducted to determine if ALS resistance could be transferred between two amaranth species, palmer amaranth and the common waterhemp. Plants of each species were grown in the growth chamber and crosses were made between herbicide resistant and sensitive plants. A total of 15 hybrids were produced from an estimated 10,000 flower cross pollinations. When hybrid plants were crossed with parents that were sensitive to the herbicide, the plants that were produced were resistant. This demonstrates that herbicide resistance that develops in one species may potentially spread to other pigweed species in the field. Pollen transfer from ALS resistant kochia plant to susceptible kochia plants may be the primary reason why ALS kochia has exploded in 1999.

CI/BIOTECH GENE TO REGULATE PLANT DEHYDRATION

    Mendel Biotechnology, Inc. has received a patent to alter the expression of cold and dehydration regulated genes in a plant by transforming a plant with CBF1 or a homologous gene, and then expressing the gene.

    CBF1 is a transcription factor that binds to the upstream region of specific cold and drought regulated genes and enhances the cold and drought resistance of plants expressing CBF1. CBF1 is being commercialized under the WeatherGard (TM) trademark.

    Mendel is working with partners to introduce the WeatherGard(TM) gene into various crops to create new stress-resistant plants. The issued patent covers technology which was developed by Dr. Mike Thomashow at Michigan State University in association with Mendel Biotechnology and has been exclusively licensed to Mendel Biotechnology. The license grants Mendel Biotechnology the right to sublicense the technology for environmental stress resistance in different crops.


GMO TESTING KITS BEING DEVELOPED

    Strategic Diagnostics Inc. has entered into diagnostic test development and licensing agreements with Monsanto to develop test kits designed specifically for detecting the presence of genetically modified traits in crops that may have been used as food ingredients. Under the agreements, Monsanto is licensing the use of their proprietary technology to SDI for the manufacture and sale of these test kits to food processors, their suppliers and regulatory bodies responsible for overseeing the labeling of
these products.

    SDI recently introduced the Soya Test Kit to detect the presence of Roundup Ready herbicide-tolerant trait in soya food ingredients. The development of a Maize Test Kit, which will detect Monsanto's YieldGuard insect-protected trait in corn-based food ingredients is underway. The latter test will be part of a multi-trait test kit that will detect all the Genetically Modified traits that have been approved in the European Union. Therefore these tests will conform to the European labeling regulations for corn-based food ingredients.

    In March 1999, the European Union food labeling regulations became effective for foods derived from genetically modified seeds. To enable consumer choice in selecting food products, the European Commission now requires food companies to label products containing foods or food ingredients derived from Genetically Modified Organisms (GMO).

Suggestions For Revision of 1996 North Dakota Weed Control Guide Sought

    Later this fall the 1999 North Dakota Weed Control Guide will be revised. If you have any ideas or suggestions to make it better, please contact myself or any one from the NDSU Weed Science Group.

    We hope the articles in this year’s North Dakota Crop and Pest Report have been beneficial to you in your weed control  efforts. With this last issue, the Weed Science group at NDSU wish you a good year, a prosperous harvest, and severe pain, misery, and death to anything deemed a "weed".

Just a farmer you said and I laughed ‘cause I knew,
All the things that a farmer must be able to do.
They must study the land and the sky,
And figure when the time is right and why.
To sow and to plant, to buy and to sell,
To go to the market with grain and well...
To pay all those taxes and be able to sleep.
And you know the fixin’ that farmers must do,
When machine like mad monsters blow a gasket or two.
I guess when God needed folks to care for His earth,
He chose just farmers ‘cause he knew their true worth.

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

 

LEARNING TO USE STEEL IN WEED MANAGEMENT, WHEN NEEDED

    In an integrated crop plan, each action toward weed control is only one part in a long-term strategy. Any specific control whether it be a herbicide or a single cultivation or a final plow-down will be a disappointment if more is expected of each, single control than it was designed to do. A successful weed control plan instead divides up weed-limiting and weed-killing roles and combines them into an integrated approach so that each action is complementary to the whole plan. And, this plan cannot
be short-term. The benefits of a well-planned, complete weed control strategy is that the benefits of crop diversity and soil improvements combine with lowered weed pressure over time. Over time is the key. The most successful weed program will be realized in multi-year strategies.

    Several critical principles are involved in sustainable, integrated weed control.

    First, give the crop the advantage. Steel tools work best when you focus on weed prevention. You will want to use tillage to lessen the vigor and number of weeds in a field. Intensive, early (and late, when needed) season weeding is important when incorporating mechanical weed control in your strategy. It keeps crops ahead by sucker punching weeds soon after germination (or before seeding). A preemerge herbicide may also work well in your early season scheme on weeds. Limit early weed competition to give the crop the advantage. Also, think long-term. Limit the amount of weed seed returned to the field.

    Second, keep weeds on the defense. This may require minimizing subsequent tillage at planting that stimulates new weed seeds. Or, it may require a varied herbicide option by varying the chemical mode of activity, the mixture or the timing. Out-compete weeds through a well-planned crop rotation. Manage the crop sequence to minimize ecological openings for weeds by using good plant populations, using crop shading to help control weeds and timing herbicide use.

    Third, accept weeds that don't really matter. Weeds are an economic problem only if they decrease yield by more than the cost of managing them (repeat this mantra over and over again). Weed species vary in the threat they pose to crops. Examine the economic threshold of weeds and how much seed they return to the weed seed bank. Determine the stage of the weed versus the stage of the crop to realize the economic cost the weed has on the crop. Determine the weeds (and their stages) that you can live with versus the weeds that are worth containing.

    Develop weed control strategies that are customized to your farm. Try to develop a long-term plan to reduce weed seed banks in each of your fields so that you can eventually reduce your annual expenses for tillage and/or herbicides. Mesh your weed control strategies with your crop rotations and soil tilth improvement. Use an integrated weed control program in order to profit in the long-run from new, high-value markets due to reduced need for weed control strategies and from higher yields from better land management while also reducing the probability of developing herbicide-resistant weed populations.

Denise A. McWilliams
Extension Crop Production Specialist
dmcwilli@ndsuext.nodak.edu


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