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ISSUE 8  June 22, 2000

 

REFLEX SECTION 18 ON DRY BEANS APPROVED

    EPA has approved a ND Section 18 Emergency Registration of Reflex on dry beans. Emergency weeds: black nightshade and common ragweed.
Weed growth stage: 1 to 4 leaves.
Rate: 0.75 pt/A (0.19 lb ai/A).
Method of application: Ground or air
Maximum number of applications: 1
Adjuvants: Petroleum oil based at 0.5 to 1 % v/v.
Thorough coverage is ESSENTIAL to weed control.
NDSU recommends at least 15 to 20 GPA.
NO not apply later than 30 days prior to harvest.
Animals (livestock) cannot graze treated fields.

 

GENERAL HERBICIDE UPDATE

Clearfield Crops Registration (American Cyanamid)
    Mode of action: ALS inhibitor
    a.i.:
Raptor, Raptor + Arsenal
    Crops:
Registration package for Clearfield canola and wheat, and dry bean, dry pea,
                alfalfa is at EPA. Clearfield HRSW wheat varieties may not be available until 2003.
                Registration for Clearfield sunflower will follow.

Drive (Top Pro/BASF)
    Mode of action: Plant growth regulator
   a.i.:
quinclorac
   Crops:
Turfgrass
   Comments:
A new postemergence herbicide for crabgrass and other weeds in cool-season
                       residential and non-residential turf. Formulated as a 75DF, Drive can be applied
                       to Kentucky bluegrass, buffalo grass and annual or perennial ryegrass.Fescue is
                       moderately tolerant. Fine fescue should be treated only if part of a blend. Do not
                       apply within 4 weeks after seedling emergence of Kentucky bluegrass and perennial
                       ryegrass. Treatment before labeled species will not affect emergence. Do not use
                      clippings for mulch around home grounds or gardens plants.

Equinox (BASF)
    Mode of action: ACCase inhibitor
    a.i.:
tepraloxydim
    Crops:
Soybean.
    Comments:
Registration unknown. Annual and perennial grass control similar to other
                        "dim" herbicides (Poast, Select, Achieve). Use rate will have a lower ai/A
                        that Poast. Rates lower, possibly less antagonism with broadleaf herbicides,
                        and greater perennial grass control than Poast (sethoxydim).

Expert (Novartis)
    Mode of action: ALS inhibitor
    a.i.: oxasulfuron
    Crops: Soybean
    Comments:
Registration on hold. Short residual, SU herbicide. E on large-seeded
                        broadleaf weeds (similar to FirstRate).

Gramoxone Extra (Zeneca)
    Mode of action: Photosystem I inhibitor
    a.i.:
paraquat
    Crops:
Potato
    Comments:
Supplemental labeling has been issue to allow use on potato as a
                        preharvest vine and weed desiccant. Use 13 to 24 fl oz/A. Use on
                        fresh market potatoes only. Do not use on potatoes that will be stored.

Milestone (DuPont)
    Mode of action: PPO inhibitor
    a.i.:
azafenidin
   Crops:
Label expected for citrus in 2000.
   Comments:
Long residual herbicide. Under current investigation for registration in cultivated
                       sunflower, cucurbits, basil, asparagus. Degree of residue and carryover may
                       determine possibility of registration on sunflower and other tolerant crops.

Paramount (BASF)
    Mode of action: Plant growth regulator
    a.i.:
quinclorac
    Crops:
Pasture/Rangeland
    Comments:
Registration on pasture/rangeland has been submitted to EPA.

Plateau (BASF)
    Mode of action: ALS inhibitor
    a.i.:
imazapic
    Crops:
CRP
    Comments:
Existing perennial grass should be controlled with glyphosate (and tillage if
                         necessary) before replanting to grass. Plateau rates used in CRP seeding will
                        not eliminate most established grasses; some cool-season species may be
                        suppressed. Labeled grasses for CRP at seeding include big bluestem, little
                        bluestem, Indiangrass, sideoats grama, blue gramma, and buffalograss.

Reglone (Zeneca)
    Mode of action: Photosystem I inhibitor
    a.i.:
diquat- NH3 salt (2 lb ai/gallon)
    Crops:
Potato
    Comments:
Reglone has been used in Canada for several years and in 2000 will now become
                        the U.S. standard formulation in the U.S. Same active ingredient as Diquat
                        (diquat- dibromide salt).  Labeled for preharvest desiccation of potato, alfalfa,
                        clover, grain sorghum, and soybean seed crops.

Rely (Aventis)
    Mode of action: Glutamine synthetase inhibitor
    a.i.:
glufosinate + adjuvants
    Crops:
Vine kill in potato.
    Comments:
Label expected in 1999. Not for seed potatoes. One application recommended
                        but initially acts slower than diquat.

Select (Valent)
    Mode of action: ACCase inhibitor
    a.i.:
clethodim
    Crops:
Canola
    Comments:
Maximum rate labeled is 5 fl oz. PHI on sugarbeet reduced to 40 days.
                        Registration on mint and field peas expected in 2000-2001.

Sonalan (Dow)
    a.i.:
ethalfluralin
    Crops:
Supplemental labeling allows use chemigation in dry beans and sunflower through pivot,
                lateral move, or end row sprinkler. Directions are specific for this use.

Stinger (Dow)
    a.i.:
clopyralid
    Crops:
A revised Section 18 label allows use in canola and removes the 2 mile buffer zone for
                the preservation of the protected prairie fringed orchid.

Valor 50DF (Valent)
    Mode of action: PPO inhibitor - Cell membrane disruptor
    a.i.:
flumioxazin
    Crops:
Soybean
    Comments:
Soybean registration expected in 2001-2002. Soil applied at 2 to 3 oz/A at 3 to 6%
    organic matter (OM) but rates should increase as soil OM decreases. Similar to Authority/ Spartan
    herbicide except no carryover. Research in dry bean, field pea, and other crops are being explored.

 

QUESTIONS AND ANSWERS

    Question: I have a farm manger that has set up tram lines in his grain fields and is planning on spraying some chemicals at night. Is there a difference in the wild oat herbicides as to which one would work better if sprayed at night. Or would the control be better during the day. He is trying to get more spraying in when the wind conditions are better and the temperatures are good if it isn't to cold.

    Answer: Unfortunately, neither weed science nor NDSU has a very good data base on night spraying of herbicides. Research conducted in MN, KS, and NE conclusively showed that weed control from glyphosate (Roundup products) was reduced when applied during the night, and early morning hours. Weed control was greatest with application under full sunlight and warm temperatures.
    A graduate student at NDSU conducted night spraying experiments in 1995 and 1996. The only grass herbicide tested was sethoxydim (Poast). The student found night spraying, especially applications early in the dark period increased control as compared to day applications.
    Since there is no other data on grass herbicides, perhaps we can discuss some principles that may affect performance and weed control of herbicides in a general sense.
    Weed control from many contact herbicides, such as, Buctril, Basagran, Liberty, Gramoxone Extra, Tough, Cobra, Blazer, Flexstar, Reflex, atrazine, Bladex, Stampede, Avenge, and Aim is greatest when applied during full sunlight and warm or hot temperatures because of the nature of their mechanism of action and because some inhibit the photosynthetic process in plants. Application of these chemicals during the night and without sunlight may decrease weed control. Adsorption into plants is rapid and generally not a problem with contact herbicides and thus adsorption is not a critical component of activity. For more information on the effects of temperature and weed control and crop response see paragraph A4 in the web version of ND Weed Control Guide. The address is on the front page of the weed guide.
    Response of systemic or translocated herbicides, like ALS or ACCase herbicides is more difficult to predict. Some factors that might affect activity are UV light, humidity, and diurnal response of weeds. ACCase herbicides are composed of two chemical families: "Dims" and "Fops" (See page 94 of the weed control guide). Dim herbicides are Poast, Select, and Achieve. UV sunlight can degrade Dim herbicides in a polyvinyl spray tank or after application before the herbicide is absorbed in the leaf. Fop herbicides, such as, Assure II, Discover, Puma, Hoelon, and Fusilade DX are not UV sensitive. Night spraying would negate breakdown of Dim herbicides by UV light but have no affect on Fop herbicides. Oil adjuvants speed the absorption of Dims and Fops which will reduce the breakdown of Dim herbicides by UV light.
    Humidity is important in absorption of water soluble herbicides into plants. Glyphosate is water soluble and shows greater weed control when applied in high humidity. ACCase herbicides are oil soluble and absorption into plants is not affected as much by high humidity in night time conditions.
    Some plants, like velvetleaf, fold their leaves into a vertical position in the night. Less herbicide will be deposited on leaves in a vertical orientation. Not all plants exhibit diurnal leaf movement but it may account for reduced weed control from night spraying in some plants.
    Lack of sunlight, higher humidity, and cooler temperatures with night spraying may allow spray droplets to remain liquid with less evaporation resulting in more absorption into plants. Use of the proper adjuvants may further increase weed control with night spraying.

Question: What garden vegetables can I plant where Treflan (trifluralin) has been applied?

Answer: Seed and transplants of broccoli, Brussel sprouts, cabbage, cauliflower, and celery. Seed of carrot, collards, green peas, lentil, lima beans, okra, radish, snap beans, and mustard or turnip greens. Before transplanting for eggplant, pepper, onions, and tomato. Postemergence (3-4 leaf) for cantaloupe, cucumber, and watermelon. Established plants of asparagus prior to spear emergence. After planting for potato.
    Mix into soil after application. Sensitive crops like beets and sweet corn may be injured the following season. Trifluralin is available in several agricultural and home ground weed control products. Do not use on lawns. Refer to product labels.

Richard Zollinger
NDSU Extension Weed Specialist

 


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