Issue 86
Prairie Grains

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Prairie Grains is the official publication of the Minnesota Association of Wheat Growers, North Dakota Grain Growers Association, Montana Grain Growers Association and South Dakota Wheat, Inc.

Copyright Prairie Grains Magazine
Summer 2007

Weed Management

12 Glyphosate Weed Control Tips

  1. Dew on plant foliage at application (or rain soon after) may reduce weed control. Glyphosate is very water soluble, which simply means that it can be dissolved in water. Dew on leaves dilutes herbicide concentration in spray droplets, and negates the effect of low spray volume at application. Allow at least a 6 hour rainfast period for all glyphosate formulations regardless of label rainfast recommendation.
  2. Glyphosate is affected by humidity. Weed control increases as humidity increases.
  3. Glyphosate is not deactivated by sunlight. Time of day application studies show that activity of glyphosate if greatest when applied after 10:00 am and before 4:00 pm.
  4. Use the lowest water volume (gpa) allowed on the label. Low spray water volumes produce spray droplets of high glyphosate concentration which results in greater absorption.
  5. Use drift management techniques, either through nozzles or adjuvants. Glyphosate is a non-selective, non-residual, translocated foliar herbicide. Glyphosate can cause severe injury or death of plants intercepting even a small amount of downwind spray droplet drift. Use drift reducing nozzles or drift reducing adjuvants to help manage drift.
  6. Glyphosate is not volatile. Glyphosate does not produce fumes or vapor after application similar to dicamba or esters of 2,4-D, MCPA. Off-target movement of glyphosate is from droplet or particle drift, not volatility.
  7. Always add AMS to glyphosate. AMS enhances absorption and translocation, deactivates antagonistic hard water salts, and the ammonium in AMS makes glyphosate-NH4 in the spray droplet, which is easily absorbed into the plant.  The NDSU recommendation is to add AMS at a minimum of 1 lb/A if using greater than 12 gpa spray volume or 4 to 6 lb/100 gallons of water. Glyphosate labels generally recommend AMS at 8.5 to 17 lb/100 gallons water. However, analysis of water across the state has shown that lower rates of AMS are adequate. AMS at lower rates will overcome antagonism from most ND water. Some locations, particularly in western ND, have hard water that exceeds 1600 ppm or even 2500 ppm of hardness and do require AMS at 8.5 to 17 lb/100 gal water. Growers should know their water quality to determine AMS rate.  Allow sufficient time for AMS to dissolve before application.
  8. Add high quality NIS if the glyphosate label allows use. NIS is used because oil adjuvants can be antagonistic. Research has shown greater weed control even when NIS was added to full load glyphosate formulations. Use reputable adjuvants from major adjuvant manufacturers. Do not believe claims of cutting herbicide rates by 50%. Data show generally less control from some “AMS replacement” adjuvants as compared to NIS plus AMS.
  9. Glyphosate applied in cool/cold weather will kill weeds – it just takes longer. Ideal temperatures for applying most POST herbicides are between 65 and 85 F. Weeds may be killed slower when temperatures remain below 50 F. Cold weather is a stress to plants. AMS and NIS can be used overcome the reduced control of stressed plants. Absorbed glyphosate will remain in the plant until warm temperatures cause weeds to resume glyphosate translocation to growing points.
  10. Weed control is reduced when glyphosate is applied to desiccated plant tissue affected by frost. Below freezing temperature may burn off top growth and desiccate plant tissue. Plant material injured by freezing temperatures will not translocate herbicides. Application to new plant growth is required for optimum herbicide activity.
  11. Dust inactivates glyphosate. If glyphosate absorption is slowed during cold weather by hardening of the cuticle (which may or may not be true) then glyphosate on the plant surface may be susceptible to inactivation from dust, especially if the wind blows. This applies also using slough water for spraying. Mud and soil in slough water will inactivate glyphosate. Addition of NIS or AMS will not overcome inactivation from dirt. Glyphosate is strongly and irreversibly absorbed to clay particles and organic matter.
  12. DO NOT USE REDUCED GLYPHOSATE RATES. The price of glyphosate has decreased to affordable levels, and weed control is relatively inexpensive compared to conventional weed control strategies. Reducing glyphosate rates may encourage the development of resistant weed biotypes, and eventually reduce the effectiveness of this key weed control tool.

Controlling Volunteer Roundup Ready Crops
Go online to www.ag.ndsu.edu/weeds/w253/w253-4d.htm for ratings of relative herbicide effectiveness. Under favorable conditions control may be better than indicated, and under unfavorable conditions herbicides may give erratic results. Dry and cool weather increases herbicide persistence while wet and/or warm weather reduces herbicide persistence.

Organic Matter, Spray Water Can Affect Herbicide Performance
Some herbicides are partially adsorbed and inactivated by soil organic matter, both high and low. Thus, test organic matter to help make herbicide product decisions. OM levels change very slowly, so testing once every 5 years should be adequate.

Spray carrier water can also reduce the effectiveness of herbicides. Water high in sodium bicarbonate reduces the effectiveness of 2,4-D and MCPA amines (not esters), Poast, glyphosate, and dicamba. High salt levels in spray water can reduce weed control in nearly all situations. Calcium and, to a lesser degree, magnesium are antagonistic to 2,4-D and MCPA amine, dicamba, and glyphosate.

Analysis of spray water sources will determine possible effects on herbicide efficacy. Water samples can be tested (for about $25) at the following laboratory: NDSU Soil and Water Environmental Laboratory, (701) 231-7864, Waldron 202, NDSU, Fargo, ND 58105-5575.

Herbicide Effectiveness Under Weather Stress
Temperatures following herbicide application can influence crop safety and weed control from herbicides. Plants metabolize most herbicides, but metabolism slows during cool or cold conditions, which extends the amount of time required to degrade herbicides in plants. Rapid degradation under warm conditions allows crop plants to escape herbicide injury.

Ideal temperatures for applying most herbicides are between 65 and 85F, and speed of kill may be slow when temperatures remain below 60F. Some herbicides may injure crops if applied above 85F or below 40F. Herbicides may be sprayed following cold night-time temperatures if day-time temperatures warm to at least 60 degrees.

Avoid applying volatile herbicides such as 2,4-D ester, MCPA ester and dicamba during hot weather, especially near susceptible broadleaf crops, shelterbelts, or farmsteads.

Wild oats is actually more susceptible to Puma and Discover during cool rather than warm/hot conditions. Green and yellow foxtail are warm season grasses and may stop growing under cold conditions, resulting in poor control. Grass and broadleaf weeds are controlled more effectively when plants are actively growing. Wild oat control from Puma is significantly reduced by drought stress. Achieve and ALS grass herbicides in wheat generally provide more consistent and greater grass control in warm, dry conditions compared with cool, wet conditions.

Other ACCase herbicides, such as Assure II, Poast, and Select, control grasses better in warm weather when grasses are actively growing. Cool or cold conditions at or following application of ACCase herbicides and significant rainfall shortly after Achieve application may increase injury to wheat.

Cold temperatures, including freezing conditions following application of ALS herbicides, Sencor, and bromoxynil, may increase crop injury of labeled crops with little effect on weed control. Delay applying fenoxaprop, ALS herbicides, and Sencor until daytime temperatures exceed 60 degrees F and after active plant growth resumes.

Basagran, Cobra, Flexstar, Liberty, paraquat, and Ultra Blazer are less likely to cause crop injury when cold temperatures follow application but less weed control may result.

2,4-D, MCPA, dicamba, clopyralid, fluroxypyr, and glyphosate (resistant crops) have adequate crop safety and provide similar weed control across a wide range of temperatures, but weed death is slowed when cold temperatures follow application.

Adjuvants can make a difference in stressed conditions. Superior adjuvants can help overcome leaf barriers like thick cuticle. Most herbicides used are translocated, so movement through the cuticle and then through the plant to growing points are critical for adequate control.  MSO type adjuvants do not cause herbicide phytotoxicity in cool weather but rather in very humid and hot weather. MSO type adjuvants usually give greater herbicide enhancement than nonionic surfactants and petroleum oil (COC) adjuvants.

Where product labels permit, addition of crop oil concentrate rather than nonionic surfactant usually results in greater herbicide activity. Some products also allow for N-based spray additives, which tend to improve efficacy of certain products during periods of slight stress.

Ultimately, follow label directions with regard to application: all herbicides have directions for use to maintain crop safety and application effectiveness.

Rain Interference with Herbicide Applications
The minimum interval between application and rain for maximum weed control varies by herbicide; it’s as little as 1 hour for products such as Beyond, Everest, Poast, Puma, Select Max and Starane, but 6-8 hours for products that include Aim, Dicamba, Stinger, and WideMatch. The time interval is 1 hour for 2,4-D ester/MCPA ester, but 4-6 hours for 2,4-D amine/MCPA amine. The 2007 N.D. Weed Control Guide, page 66 (www.ag.ndsu.edu/weeds/w253/w253-3a.htm) lists the minimum interval between herbicide application and rain for maximum herbicide uptake and efficacy.  Follow the label for more instruction.

Managing Tank Solution with Delayed Spraying
A spraying delay from rain or other reasons may result in a partial sprayer tank load of unused herbicide solution.  Problems may occur as the spray solution sets in the tank waiting for the field to dry enough so the remainder of the spray can be applied. Some herbicides degrade slowly as they set in a water solution, but most formulated herbicides will retain most of their activity over a few days. The exact amount of degradation is affected by water temperature, water pH, and the active ingredient in the tank, so predicting the rate of degradation is not precise.

Some herbicides and herbicide combinations may settle out of suspension with time, so gentle agitation may be needed to prevent the herbicide from forming a layer on the bottom of the tank. Adding fresh water and herbicide to a sprayer with old spray solution is not a good idea if the herbicides in the sprayer are among those which may plug screens and nozzles after setting for a time. Dealing with a partial load of a plugging problem is much better than dealing with a full load.

Finding a way to apply an aged spray solution to a registered crop is always better than dumping the herbicide solution. Most of the benefit of the herbicide will still be realized even if some degradation has occurred, so the total value of the herbicide will not be lost. Removal of the screens at the nozzles and increasing spray pressure will nearly always allow application of an aged spray solution, especially if it was kept in suspension by gentle agitation.

Increased spray pressure will increase application rate, but this will be partially offset by the reduction in activity of the herbicide. Increasing spray pressure from 40 psi to 60 psi will increase spray volume by about 20% and increasing spray pressure from 40 psi to 80 psi will increase spray volume by about 40%. The amount of increase in spray pressure can be adjusted based on estimated herbicide degradation, label limits on herbicide rates and the amount of precipitate in the spray solution.

Using Herbicides at Reduced Rates
Ideally, control of target weeds at the lowest herbicide rate provide the greatest return over herbicide and application costs. This “best” herbicide rate will be different for every combination of herbicide-weed-environment-adjuvant combination. Sometimes, the “best” rate will be lower than the lowest rate on the herbicide label. Following are factors considered by companies when they write a label.

  • Weed Size and Crop Size. Companies make an assumption of weed and crop size at herbicide application. Small weeds are more susceptible to herbicides than large weeds, but small crop plants may also be more susceptible. Reduced herbicide rates may be used if herbicides are applied to weeds smaller than listed on label. The crop will also probably be smaller, so knowledge of crop safety also is needed.
  • Environment. Companies write labels that cover most environments in which herbicides are used. Environment has a large influence on the efficacy of herbicides. Herbicide rates may be reduced under ideal environmental but special knowledge is needed on the environment-herbicide interaction.
  • Adjuvants. Most POST herbicides require addition of adjuvants such as surfactants, crop oils, methylated seed oils, or fertilizer. See section on spray adjuvants (A5) for more information. Adjuvant information is fairly general on pesticide labels to address adequate weed control under most situations. Herbicide rates sometimes can be reduced by using adjuvants that are highly effective with a specific herbicide but additional knowledge is needed. The herbicide-adjuvant combination must be safe on the crop as well as provide good weed control.
  • Method of Application. Special knowledge of the best application method for a specific herbicide and situation may allow a reduction in herbicide rate.
  • Weed Species. Labels sometimes list weed species separately on the label with different rates for different weeds. Herbicide rates may be reduced when highly susceptible weed species are present.
  • Performance Complaints. Using reduced rates may result in poor weed control. User assumes all risk and liability of unacceptable weed control when less than labeled rates are used.
  • Are Low Rates Legal? A herbicide user can legally choose a rate lower than listed on the herbicide label unless the label specifically prohibits low rates. However, the company has no obligation to support herbicide efficacy when the application rate was less than labeled rates. Herbicide users should not expect a company representative to provide any comfort or assistance if weed control is less than expected from a rate of herbicide that is less than the labeled rate.

Reducing Spray Drift
Adjust boom as close to the target as possible while maintaining uniform spray coverage. Choose nozzles with a wide angle over narrow angle nozzles.

Some herbicides volatilize under warm or hot temperature and cause plant injury from vapors or fume drift. Temperature on the soil surface often is several degrees warmer than air temperature. Herbicide vapor can drift further and over a longer time than spray droplets. Wind blowing away from susceptible plants during application will prevent damage from droplet drift but a later wind shift toward the susceptible plants could move damaging vapors to the plants.

Low volatile esters of 2,4-D or MCPA may produce damaging vapors between 70 to 90 F. Amine formulations are essentially non-volatile even at high temperatures. To minimize the risk of drift injury, dicamba and ester formulations of 2,4-D and MCPA should not be used near susceptible plants.

Several sprayer nozzles designed to reduce spray drift are available; these drift -reducing nozzles are flat-fan types and are adapted for conventional spray equipment. Small plastic cones that fit around individual nozzles reduce drift by approximately 25 to 50%, and spray shields which enclose the entire boom reduce drift by approximately 50 to 85%. Spray shields provide greater drift reduction when winds are low and droplets are relatively large. Therefore, spray shields should not be used as a substitute for other drift control techniques but as a supplement to all other applicable methods of drift reduction.

Spray drift can be reduced by increasing droplet size and droplet size can be increased by reducing spray pressure, increasing nozzle orifice size, special drift reduction nozzles, additives that increase spray viscosity, and rearward nozzle orientation on aircraft.

For more detailed information on managing spray and vapor drift, efer to NDSU Extension Circular A-657, “Herbicide Spray Drift” and Circular WC-751 “Documentation for Suspected Herbicide Drift Damage,” both of which can be found on the Internet under NDSU online weed control publications: www.ext.nodak.edu/extpubs/weeds.htm

Evaluate Late-Season Glyphosate Treatments
Weeds that poke heads through the soybean canopy later in the growing season may tempt growers to load up the sprayer for one last trip across the field. However, potential value of these late season treatments should be evaluated prior to spraying. Realize that impact on yields has already occurred, thus little yield benefit is likely to be achieved. If the weeds have not initiated seed set at the time of application, it should be possible to reduce seed production. However, if the fruiting structure is visible, it is unlikely that killing the weeds at this late date will influence seed production or viability of the seed. Many people think that late season treatments will reduce the viability of seeds that are produced, but research has consistently shown that seeds that have been initiated at the time of application are unlikely to be greatly influenced. The other possible benefit of the late season treatments is harvesting efficiency, and there may be situations where this may make the treatment worthwhile.

Seven Tips to Avoid Herbicide Crop Injury
These days, we need to be careful and clean herbicide residues out of the sprayer even when switching between different corn or soybean types. For example, a conventional corn hybrid could be damaged by a sprayer contaminated with glyphosate after spraying Roundup Ready corn.  Some of the most serious contamination problems are glyphosate injury to corn and dicamba injury to soybeans. Both of these crops are very sensitive to these herbicides.

Severity of crop injury will vary by herbicide and also depends on factors such as weather conditions, crop growth stage, and adjuvants.  Some guidelines to consider regarding tank contamination:

  1. Once injury occurs, there is no fix.
  2. Postemergence-applied herbicides are more likely to injure crops than herbicides applied preemergence because the herbicide is applied directly to the leaves rather than being diluted in the soil. Also, several preemergence herbicides have little or no foliar activity. Therefore, be especially careful to clean postemergence herbicide residues from spray equipment.
  3. Systemic herbicides like glyphosate, dicamba and other growth regulators, ALS inhibitors (Accent, Raptor, etc) and ACCase inhibitors (Assure, Poast, etc.) are a greater concern than contact herbicides, because systemic herbicides damage the growing point. Contact (non-mobile) herbicides only damage sprayed leaves. Relatively high concentrations of contact herbicide residues are required to cause long-term damage in most cases. However, low concentrations of systemic herbicides can cause serious damage.
  4. Just spraying until a tank is empty does not mean that all the herbicide is removed from the spraying system (sump, filters, pump, lines, etc.). Proper cleaning and rinsing is needed to remove the remaining spray solution or herbicide residues.
  5. Clean spray equipment as soon as possible after use. Dried residues are more difficult to clean and remove.
  6. Follow the label’s directions for the best cleaning agent to use. On several labels, you will note that the cleaning procedures recommend that the cleaning solution stand in the sprayer for several hours to overnight. Cleaning a spray tank is not a job that should be rushed, especially with certain herbicides that are highly active on sensitive crops.
  7. Never add chlorine bleach to ammonia or liquid fertilizers that contain ammonia, because toxic chlorine gas can be formed.

Five Steps to Proper Sprayer Cleanout
Proper sprayer cleanout procedures are given on many herbicide labels, and the procedure on the label should be followed for specific herbicides. The following procedure illustrating a thorough sprayer cleanup procedure is effective for most herbicides:

  • Step 1. Drain tank and thoroughly rinse interior surfaces of tank with clean water. Spray rinse water through the spray boom. Sufficient rinse water should be used for 5 minutes or more of spraying through the boom.
  • Step 2. Fill the sprayer tank with clean water and add a cleaning solution (many labels provide recommended cleaning solutions). Fill the boom, hoses, and nozzles and allow the agitator to operate for 15 minutes.
  • Step 3. Allow the sprayer to sit for 8 hours while full of cleaning solution so the herbicide can be fully desorbed from the residues inside the sprayer.
  • Step 4. Spray the cleaning solution through the booms.
  • Step 5. Clean nozzles, screens, and filters. Rinse the sprayer to remove cleaning solution and spray rinsate through the booms.

Common types of cleaning solutions are chlorine bleach, ammonia, and commercially formulated tank cleaners. Chlorine lowers the pH of the solution, which speeds the degradation of some herbicides. Ammonia increases the pH of the solution, which increases the solubility of some herbicides. Commercially formulated tank cleaners generally raise pH and act as detergents to remove herbicides. Read herbicide label for recommended tank cleaning solutions and procedures. Never mix chlorine bleach and ammonia, as a dangerous and irritating gas will be released.

Sprayers should be cleaned as soon as possible after use to prevent the deposit of dried spray residues. A sprayer should not remain empty overnight without cleaning; fill the tank with water to prevent dried spray deposits from forming.

Questions to Ask If You Suspect Herbicide Resistance

  • Was the correct herbicide rate and adjuvant added to the spray tank?
  • Was application and spray coverage adequate?
  • Was the environment favorable for herbicide performance (unstressed plants)?
  • Did only one weed species escape control (weed escapes may be localized in patches)?
  • Is the suspected resistant weed mixed in with other weeds of the same plant type that were controlled?
  • Does the herbicide typically control the weed species that escaped control?
  • Has the herbicide (or herbicides with the same mode of action) been used frequently in the past?
  • Have other cases of resistance been confirmed in the area?

One may strongly suspect the presence of a herbicide-resistant weed with a yes answer to these questions. If possible, pull or till suspected herbicide-resistant weeds to restrict their spread.  Rotate herbicides with different modes of action, apply herbicides in tank-mix/multiple modes of action, and rotate crops to help minimize herbicide resistance. See section on herbicide resistant weeds in NDSU Weed Guide: Go online to www.ag.ndsu.edu/weeds/w253/w253w.htm   - scroll down to table of contents text (bottom half of page) and see information under ‘herbicide resistant weeds.’ Other online information sources for herbicide resistance management:

Considerations in Preharvest Weed Control
Following are some factors to consider before applying a herbicide as a harvest aid:

  • The expectations for preharvest weed control usually exceed reality - it is not possible to kill or dry down a three-foot weed in the same manner as a three-inch weed. Lower portions of the weed may not be affected.
  • It requires time to dry down treated weeds - usually 7-10 days. It may require more time if wet and/or cool weather conditions occur after treatment. All herbicides labeled for preharvest application are systemic and slow acting, which requires a longer dry down period as compared to contact, fast acting herbicides.
  • Glyphosate is labeled as a harvest aid only in spring wheat and durum - not barley or oats. Glyphosate at 0.5 to 2 pt/A of a 3 lb ae/gal concentrate controls annual grass, broadleaf weeds, and quackgrass and suppresses Canada thistle in hard red spring wheat and durum. Do not apply to barley.  Do not apply to wheat grown for seed, as a reduction in germination or vigor may occur.
  • Glyphosate should be applied after the hard dough stage (30% or less grain moisture ) of the wheat and at least 7 days prior to harvest by air or ground in 3 to 10 gpa spray volume. Applying glyphosate before physiological maturity can reduce yield, test weight and seed germination. See label for adjuvant use. Always add AMS at 8.5 to 17 lb/100 gallons of water. AMS increases control of annual and perennial weeds and especially control of weeds stressed by dry weather. AMS also eliminates antagonism from ions and carbonates in hard water. Do not use AMS in place of an NIS. Refer to label for addition of other adjuvants.

Herbicide Storage Temperatures
Herbicides may be exposed to freezing temperatures in storage. The following products have no storage temperature restrictions: Bronate Advanced, Dicamba, Metolachlor, EPTC, Outlook, Glyphosate-K, Select, Surpass, Touchdown. Maverick, and most dry formulated herbicides in DF or WDG formulations. Most others have restrictions below 40 F, to a varying degree.  Check the label and store accordingly.

  • Weed Info Online
    North Dakota State University:
    www.ag.ndsu.edu/weeds (with links to weed I.D., 2007 ND Weed Control Guide, Section 18 status, herbicide label search)
  • South Dakota State University: http://plantsci.sdstate.edu/weeds
  • University of Minnesota: http://appliedweeds.coafes.umn.edu
  • North Central Weed Science Society web site with links to extension publications from most Midwest universities:  www.ncwss.org - Click on “Publications” then “Midwest Web Extension Publications.”  From there you can get a large variety of extension materials, including herbicide mode of action and pictures of herbicide symptomology.
  • Pesticide Labelswww.cdms.net/manuf/manuf.asp  
  • Greenbook: www.greenbook.net – Known in weed science circles as the ‘Green Bible’ that contains labels for most all pesticides currently labeled.

Take Advantage of Pesticide, Container Disposal Programs

Follow The APPLES Sequence When Tank Mixing

The NDSU Extension Service recommends the A.P.P.L.E.S. sequence for adding herbicide formulations to a tank partially filled with water:

Agitate

Powders soluble,

Powders dry,

Liquid flowables and suspensions,

Emulsifiable concentrates

Solutions – add surfactants, petroleum oils, MSO (methylated seed oil) type and other adjuvants last.

NDSU Grass Herbicides for Wheat and Barley Quick Reference Guide (Apr, 2007)

Axial

Discover

Everest

Puma

Rimfire

Crop

Winter and HRS wheat, barley

Wheat

Wheat

Wheat and barley

Wheat

Crop stage

2-leaf to boot

2-leaf until prior to boot

emergence to prior to jointing

Wheat: emergence to 60 days before harvest. Barley:1-4 leaf

1-leaf to flag leaf emergence

Grass weed stage

1-6 leaf + 3 tillers

1-5 leaf foxtail and  1-6 leaf wild oat

up to 4 leaves

1 leaf to 2 tiller

1 leaf to 2 tiller

Mode of Action

“ACCase Inhibitor”

“ACCase Inhibitor”

ALS inhibitor

“ACCase Inhibitor”

ALS inhibitor

Application rate/A

8.2 fl oz

3.2 and 4 fl oz; NG 12.8 and 16 fl oz

0.3-0.6 oz

0.33-0.66 pt

1.75-2.25 oz

Cost ($/A)

12.75

12.50-16.25

10.50-15.50

7.75-16

8.25-10.75

Adjuvant

Adigor 9.6 fl oz/A (co-pack) 

DSV (co-pack); MSO 0.25% may be added

NIS 0.25% or basic pH blend 1% if no EC or ester broadleaf herbicides

mefenpyr safener (prepackaged)

MSO 1.5 pt/A, or NIS 0.5% + UAN 1-2 qt/A, or basic pH blend 1%

Residual for weed control

No

No

Yes

No

Yes

GPA ground

5 - 10

10-May

5 - 10

5-10

10-15

GPA Air

5   

3   

3 - 5

5   

5   

Rainfast (hours)

0.5

0.5

1   

1   

4   

PHI (days)

60   

60   

60   

     wheat -60      
barley - 57

71   

Crop rotation restrictions beyond next crop season (months after application)

No

No

oat - 18; chickpea and lentil - 24

No

corn, CRP grass, potato and sugarbeet - 12

Grass weed control (E=90-99%, G=80-90, F=65-80, P= 40-65% control)

Wild Oat

E1

E1

G-E2

E1

G-E

Green foxtail

E1

E1

E

E1

P-F

Yellow foxtail

G-E1

G-E1

P-G

E1

P-F

Barnyardgrass

G-E

E

F-G

E

G

Downy Brome

None

None

P-F

None

P-F

Japanese Brome

None

None

G

None

G

Persian Darnel

E

G-E

F-G

NA

F-G

Foxtail Barley

None

None

F

None

F-G

Quackgrass

None

NA

P-F

None

F

Selected annual broadleaf weed control

No

No

Yes

No

Yes

Tank mixtures

see labels

1Except ACCase resistant plants.            2Except ALS resistant plants.
Developed by Greg Endres, NDSU Area Extension Agronomist, Carrington

Summary of influences of various factors on spray drift

Factor

More Drift

Less Drift

Spray particle size

Smaller

Larger

Release height

Higher

Lower

Wind speed

Higher

Lower

Spray pressure

Higher

Lower

Nozzle Size

Smaller

Larger

Nozzle Orientation (aircraft)

Forward

Backward

Nozzle Location (aircraft)

Beyond 2/3 wing span

2/3 or less wing span

Air Temperature

Higher

Lower

Relative Humidity

Lower

Higher

Nozzle Type

Produce Small Droplets

Produce Larger Droplets