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ISSUE 9   JULY 1, 1999

 

PURPLE LOOSESTIFE IDENTIFICATION AND CONTROL TOUR

    Mark your calendars now for Friday July 16th and plan to attend a purple loosestrife tour to be held at Chautauqua Park in Valley City beginning at 1 pm. The tour is being held at Valley City because this site has the most successful establishment of biological control agents introduced into North Dakota for purple loosestrife control. Rod Lym, NDSU Invasive Weed Specialist will be present to discuss how to identify purple loosestrife, why it was put on the state noxious weed list, and how to control the weed using chemical and biological control agents. The tour will also include discussion on the life cycle of the introduced biocontrol insects and how to identify them. Jim McAllister, the Barnes County Weed control officer will be present to discuss the control efforts being conducted in the county, and John Leppert of the North Dakota State Dept. of Ag will discuss the statewide efforts to control this invasive weed.

    Purple loosestrife, also known as lythrum, was added to the states noxious weed list in 1996 and is the first horticultural plant to be declared noxious in North Dakota. Purple loosestrife, a beautiful garden plant with an aggressive nature, was first introduced into North America in the early 1800s. The plant has been sold in North Dakota by its genus name Lythrum for at least 50 years. Lythrum plants were brought to North Dakota for flower gardens because of their striking color, ease of growth, winter hardiness, and lack of insect or disease problems. The garden varieties of purple loosestrife were sold by many cultivar names including Morden Pink, Dropmore Purple, and Morden Gleam. These garden cultivars were thought to be sterile but have now been shown to cross-pollinate with the wild Lythrum type and sometimes with other Lythrum cultivars.

    The major impact of purple loosestrife invasions is on the ecology of aquatic sites. Purple loosestrife forms dense monotypic stands as it displaces native wetland plants. Under optimum conditions, a small isolated group of purple loosestrife plants can spread to cover aquatic sites in just one growing season. When purple loosestrife replaces native vegetation it also can displace wildlife. For example, songbirds do not consume the small hard seed. Muskrats use cattails to build their homes, and they show a preference for cattail over purple loosestrife for food. Waterfowl, especially ducks, avoid wetlands that have become dominated with purple loosestrife. In addition, overall waterfowl production is decreased as suitable nesting habitat is eliminated. The plant's growth is generally too compact to offer cover, and cover may be as crucial to wildlife as food.

    Purple loosestrife has been heavily utilized in North Dakota flower gardens, park plantings, and golf courses. North Dakota law allows previously established Lythrum plantings to remain if the plants do not produce seed and present no danger of spreading to aquatic sites. However, if the Lythrum plantings produce seed or could spread to aquatic sites they must be eradicated. Aquatic sites are defined as rivers, lakes, sloughs, dams, dugouts, bogs, swamps, irrigation ditches, streams (perennial or semi-permanent) and other water courses, or wet sites. Weed boards will determine on a case-by-case basis which ornamental Lythrum plantings present a threat to aquatic sites.

Rod Lym
NDSU Invasive Weed Control Research
lym@plains.nodak.edu

 

CRISIS EXEMPTION DECLARED FOR STINGER - FLAX

    ND Dept of Ag has declared a crisis exemption for Curtail M on flax to control Canada thistle and perennial sowthistle.

    The crisis exemption allows for a single application at a rate of 1.33 to 1.75 pints/A to thistle 4 to 6 inches tall. The product must be mixed in 10-20 gallons of water per acre. Flax treated with Stinger must not be grazed or fed to livestock. Producers cannot apply the product within 100 feet of any surface water, including wetlands, lakes, reservoirs, or rivers. Applicators must follow all instructions, warnings and precautions on the product label. The exemption expires on July 31, 1999.

    This is the fifth crisis exemption declared by Johnson this year. The North Dakota Department of Agriculture has submitted a total of twenty-seven section 18 applications to the EPA. Five applications are pending review.

 

CRISIS EXEMPTION DECLARED FOR STINGER - CRAMBE

    ND Dept of Ag has declared a crisis exemption for Stinger on crambe to control Canada thistle and perennial sowthistle.

    The crisis exemption allows for a single application at a rate of 0.33 pints/A to thistle 4 to 6 inches tall. The product must be mixed in 10-20 gallons of water per acre. Crambe treated with Stinger must not be grazed or fed to livestock. Producers cannot apply the product within 100 feet of any surface water, including wetlands, lakes, reservoirs, or rivers. Applicators must follow all instructions, warnings and precautions on the product label. The exemption expires on July 31, 1999.

    This is the fifth crisis exemption declared by Johnson this year. The North Dakota Department of Agriculture has submitted a total of twenty-seven section 18 applications to the EPA. Five applications are pending review.

 

RAPTOR ON DRY BEAN SECTION 18 AMENDED

    ND has received approval to amend the ND Section 18 for Raptor on dry edible beans to expire on July 31 instead of June 30.

    Raptor herbicide may be applied by air to dry beans. Uniformly apply with properly calibrated aerial equipment in 5 or more gallons of water per acre with adjuvant recommended on the label. To avoid injury to sensitive crops from drift, aerial applicators must adhere to the following:

- Nozzle height above ground must be a maximum of 10 feet.

- Nozzles must be pointed toward the rear of the aircraft.
    The downward angle of the nozzle should not be greater than 20 degrees.

- To minimize wing-tip vortex roll, nozzles or spray boom must not be located any closer
    to end of wing or rotor than three-fourths the distance from the center of the aircraft.

- Use a maximum spray pressure of 40 psi.

- A buffer zone must be established between the area to be sprayed and sensitive crops.

- DO NOT spray when wind velocity is greater than 5 mph.

- Coarse sprays (larger droplets) are less likely to drift.

    Applicator is responsible for any loss or damage which results from spraying RAPTOR in a manner other than recommended in this label. In addition, applicator must follow all applicable state and local regulations and ordinances in regard to spraying.

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

 

GROWTH REGULATOR HERBICIDES CAN AFFECT CORN

    Cool, wet spring weather initiated stress on corn planted early in May and again affected corn planted during the cold weather experienced in mid-May. Ample moisture in many areas has also limited root growth. From this pre-conditioning, corn generally has not had as extensive a root system as normally develops by the four to five-leaf stage. Addition of other stresses such as any soil compaction, on-off aerobic conditions in saturated soils, cool soils and temperatures and limits on some fields to nutrients (due to nitrogen losses from rainfall and wet soil conditions and slower uptake by the plants of nutrients) have all affected corn growth and development.

    Recent postemergence herbicide use has had excellent control on weeds. Higher than normal humidity and excellent growth conditions for plants has allowed lower labeled rates to work well on weeds. However, this excellent growth has also stimulated corn growth, adding one more stress on the corn plant for energy reserves.

    With the current conditions, application of any growth regulator mode of activity herbicide should be carefully considered, including uses of: 2,4-D, Scorpion III, Banvel, Clarity, Stinger, Distinct, or Celebrity or other mixes with 2,4-D or dicamba . Check the fields for general plant health and determine the optimum rate of application based on need and environmental conditions just before, during and possibly (if weather change is suggested in the forecast) just after application. If continued weather conditions show high humidity in the cards at the time of application and neither the weeds or crop plants are stressed good to excellent chemical activity will occur across the field. Carefully read label instructions on additives and surfactants for the applications. Consider application rates that are needed specifically for controlling the weeds in the field as specified by the label. Over application or overlaps in the field while spraying corn fields that have stressed corn plants can result in wrapped or goosenecked leaves and later applications during rapid corn growth from the sixth leaf until tasseling can cause less stalk strength, with more potential for greensnap. Follow application restrictions, including use of drop nozzles on specified herbicides applied later in the season.

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

 

POST-EMERGENCE HERBICIDES FOR FLAX

    A limited number of post-emergence herbicides are labeled for weed control in flax. Bromoxynil (tradenames include Broclean, Buctril, Moxy) is labeled at 1 pint per acre to 2- to 8-inch tall flax for broadleaf weed control. Bromoxynil will provide good or excellent control of numerous weeds including wild buckwheat, cocklebur, kochia, lambsquarters, marshelder, eastern black nightshade, common ragweed, annual smartweed, sunflower, and Russian thistle. MCPA applied at 1 pint per acre (4 pound per gallon concentrate) to 2- to 8-inch tall flax will provide good or excellent control of broadleaf weeds including cocklebur, flixweed, lambsquarters, marshelder, wild mustard, common ragweed, and sunflower. Bromoxynil and MCPA may be tank-mixed to increase the spectrum of broadleaf weed control. Potential for flax injury exists with either herbicide used alone or as a mixture. Poast at 0.5 to 1.5 pints per acre is labeled for grass control in pre-bloom flax. A second application is recommended to provide fair-to-good control of quackgrass. Apply Poast with one quart per acre of an oil additive to actively-growing grasses. Poast may be tank-mixed with bromoxynil or MCPA ester for broad spectrum weed control. Crop injury and reduced grass weed control may occur with the tank mixtures. Refer to herbicide labels and NDSU Extension Service circular W-253 "1999 North Dakota Weed Control Guide" for required information on use.

 

VOLUNTEER SUNFLOWER CONTROL IN WHEAT AND CORN

    Volunteers from last year's sunflower fields are emerging in fields planted to wheat and corn this season. Emergence of volunteer sunflower may occur over an extended period of time depending on previous tillage operations, current soil conditions, etc. Volunteer sunflower is quite competitive with grass crops. NDSU studies have indicated a sunflower density of 50 plants per square yard can reduce wheat yield by 40 percent. Post-emergence herbicides should be applied before sunflower is four-inches tall and a second treatment may be needed for late-emerging sunflower.

    Post-emergence herbicides rated by NDSU that provide good-to-excellent or excellent control of volunteer sunflower in wheat include the sulfonylurea herbicides + 2, 4-D, dicamba or dicamba + MCPA amine, bromoxynil or bromoxynil + MCPA, Cheyenne (HRS wheat only), Curtail or Curtail M, Starane + 2,4-D or MCPA, Tiller (HRS wheat only), Tordon + 2,4-D or MCPA (HRS wheat only), and 2, 4-D.

    Post-emergence herbicides rated by NDSU that provide good-to-excellent or excellent control of volunteer sunflower in corn include Accent Gold, Banvel or Clarity, Basagran, Bladex + oil, Celebrity, Curtail, Distinct, Hornet, Liberty (Liberty tolerant corn only), Permit, Scorpion III, Stinger, and 2,4-D. Refer to herbicide labels and NDSU Extension Service circular W-253 "1999 North Dakota Weed Control Guide" for herbicide rates, correct weed and crop stages for herbicide application, and other specific information regarding herbicide use.

Greg Endres
Extension Agronomist
Carrington R&E Center
gendres@ndsuext.nodak.edu


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