Pre-Harvest Weed Control Tips

Pre-harvest weed control with glyphosate is very effective for the control of perennial weeds such as Canada thistle, perennial sow-thistle, quackgrass and dandelion.

Pre-harvest weed control also provides significant harvest management benefits such as quicker drydown, more uniform maturity, increased combine efficiency and earlier harvest.

Registered crops include wheat, barley, oats, canola, flax and peas.  Application to crops should occur when moisture content is 30% or less.  In cereals, this is at the hard dough stage when a thumbnail impression will remain on the kernel.  In flax and peas, the majority of bolls and pods are brown.

Best weed control is achieved when Canada thistle and perennial sow-thistle are sprayed at or beyond the bud stage.  Quackgrass control is best when there are 4 to 5 or more green leaves.  To control dandelion, plants should be actively growing and at the bud to bloom stage.  (Dandelion may be more effectively controlled with a post-harvest treatment due to better coverage and translocation.)

Post-Harvest Weed Control Tips

Post-harvest weed control is another great opportunity to clean up fields and prepare for next year’s crop.

Glyphosate is commonly used in post-harvest weed control programs, however with the increasing concern for glyphosate-resistant weed development, growers should be utilizing multiple modes of action.

Glyphosate tank-mixes with Express SG or Inferno allow recropping to cereals, canola, flax and soybeans next season.  For residual control of broadleaved weeds, Express Pro tank-mixed with glyphosate or PrePass XC will be effective.  Only cereals can be recropped next spring after the application of these two products.  Paradigm is another option for post-harvest application which offers “Just Go” benefits and multiple modes of action, mix Paradigm with glyphosate,  recrop to wheat or barley next spring.

New options for post-harvest weed control include Heat or Distinct tank-mixed with glyphosate.  These products provide different modes of action and broad-spectrum control.  Check product labels for recropping options as these vary by the date of the post-harvest application.

With weed and disease control generally being completed on most fields, growers have an excellent opportunity to do some “Crop CSI”.  Field observations made at this time of year can help uncover any problems and direct future improvements to crop production strategies.  Some of the key areas to pay attention to include:

• Stand Establishment: Are your crops even and uniform?  If not, perhaps adjustment to seeding equipment may be required.  Possibly seed quality or not using a seed treatment is the issue.
• Fertility: Are there yellowy streaks or areas of poor crop development?  Fertilizer application or rates may be in question.  Be sure to check for good nodulation in soybeans.
• Weed Control:  Have all herbicides performed well or are there escapes?  Do the escapes occur in patterns i.e. suggesting problems in application.  Get the escaping weeds identified, so that a better herbicide option can be used.  Check suspicious patches for development of weed resistance and make arrangements for seed collection to do a resistance test.  Make note of potential weeds that should be looked after in a pre-harvest application.  Keep fall timing in mind for post-harvest herbicides such as PrePass, Avadex, and Edge.
• Disease Control: Compare sprayed areas with any checks to verify level of control.  You may be able to detect fusarium head blight or sclerotinia symptoms especially in a bad disease year.  Be sure to check plant roots in suspicious areas for presence of root rots or clubroot.
• Insect Scouting: Summer months can bring unwanted guests to your fields such as Bertha armyworm, diamond-back moths, and lygus bugs in canola.  Soybeans may be threatened with aphids or spider mites.  Do regular checks to monitor for outbreaks.
• Varietal Performance: Keep notes on plant stature i.e. height, tendency to lodge, podding height.  Are there differences in susceptibility to disease?  These observations can help guide you with future varietal selection.

Remember to keep good records and notes of your field observations so that you can act upon the issues you have identified.  Good luck with your Crop CSI and please contact your local Shur-Gro or Munro agronomist for assistance with your investigations!

Fungicides

Cotegra (BASF), SRP $21.73 – $24.83/ac (9.8 L jug treats 35 – 40 ac)

• boscalid (Group 7) pre-formulated with prothioconazole (Group 3)
• brings together the actives in Lance and Proline
• for sclerotinia and white mold control in canola and pulses including soybeans
• apply at early flowering prior to disease development
• convenient liquid formulation

Dyax (BASF), SRP $22.99/ac (9.6 L jug treats 60 ac)

• pyraclostrobin (Group 11) and fluxapyroxad (Xemium, Group 7) for disease control in pulses including soybeans
• increased levels of (fluxapyroxad) for improved disease control
• apply at start of flowering

Nexicor (BASF), SRP $12.70/ac (8 L jug treats 40 ac)

• pyraclostrobin (Group 11), fluxapyroxad (Group 7), and propiconazole (Group 3) for disease control in cereals and canola
• broad-spectrum leaf disease control in cereals applied at stem elongation to early heading. Blackleg control in canola applied at 2 to 6 leaf stage.

Trivapro (Syngenta), SRP $15.79/ac (1 case treats 40 ac)

• azoxystrobin (Group 11), benzovindiflupyr (Solatenol, Group 7), and propiconazole (Group 3) for disease control in cereals and soybeans
• broad-spectrum leaf disease control in cereals applied at early flag leaf stage
• disease control in soybeans applied at first sign of disease

Elatus (Syngenta), SRP $20.02/ac (1 case treats 40 ac)

• azoxystrobin (Group 11) and benzovindiflupyr (Group 7) for disease control in pulses including soybeans
• maximum of one application at the beginning of flowering

Delaro (Bayer), SRP $21.70/ac – peas (7.1 L jug treats 20 ac),  SRP $14.47/ac – soybeans (7.1 L jug treats 30 ac)

• prothioconazole (Group 3) and trifloxystrobin (Group 11) for disease control in pulses including soybeans
• broad-spectrum disease control for all major pulse and soybean stem, leaf and pod diseases
• apply at the beginning of flowering or at first sign of disease

Prosaro XTR (Bayer), SRP $21.22/ac (6.5 L jug treats 20 ac)

• prothioconazole and tebuconazole (Group 3s) for disease control in cereals, the addition of mefenpyr-diethyl enhances the crop’s defense system
• broad-spectrum leaf disease control and suppression of fusarium head blight
• helps plants mitigate the effects of environmental stresses resulting in higher yield performance vs. regular Prosaro

Note:  Please refer to specific product labels before use.

Pre-seed Burndown

Paradigm (Corteva), SRP $6.44/ac (0.8 kg jug treats 106 ac)

• Group 2+4 for spring wheat, winter wheat, and barley
• prior to seeding and no later than 48 hrs after seeding
• 15 days residual control
• mix with any glyphosate product

Blackhawk (Nufarm), SRP $6.25/ac (9 L jug treats 30 ac)

• prior to seeding cereals (apply 7 days prior to seeding oats)
• contains pyraflufen (Group 14) and 2,4-D ester (Group 4)
• mix with glyphosate

Conquer (Nufarm), SRP $7.40/ac (1 case treats 80 ac)

• pre-seed weed control for canola
• carfentrazone (Group 14) and bromoxynil (Group 6), mix with glyphosate
• controls volunteer canola as well as Group 2+9 resistant weed biotypes

Aim (FMC), SRP $3.90 – $7.74/ac (2 L jug treats 67 – 133 ac)

• pre-seed for cereals, pulses, and canola
• carfentrazone (Group 14), mix with glyphosate
• can mix with 2,4-D (cereals), MCPA (flax or peas), bromoxynil (canola)

Command (FMC), SRP $7.99/ac (5.4 L jug treats 40 ac)

• pre-seed weed control for canola
• clomazone (Group 13), mix with glyphosate
• pre-emergent control of cleavers, does not control cleavers already emerged

Focus (FMC), SRP $16.31 – $24.71/ac (4.5 L jug treats 33 – 50 ac)

• pre-seed or pre-emergence for spring wheat, winter wheat, soybeans, and corn
• carfentrazone (Group 14) and pyroxasulfone (Group15)
• rate is 33-50 ac/jug. Use higher rate when organic matter is 4-7%, low rate when it is 1-4%
• controls both grassy and broadleaf weeds. Grassy weeds controlled include barnyard grass, green and yellow foxtail, downy and Japanese brome. Wild oats and foxtail barley are suppressed.  Broadleaf weeds controlled include cleavers, redroot pigweed, and wormseed mustard.  Kochia, wild buckwheat, wild mustard, and lamb’s quarters are suppressed.
• soil incorporation is not required, a minimum of 0.5 inch rainfall will get herbicide into solution and available for uptake by weeds
• tank mix with glyphosate for faster burndown of emerged weeds
• spring wheat (not durum), soybeans, and field corn can be grown in the spring following a fall application or next growing season after a spring application

Broadleaf Herbicides

Cirpreme (Corteva), SRP $10.45/ac (1 case treats 80 ac)

• for wheat and barley
• co-pak of Paradigm and Lontrel for annual and perennial broadleaf weed control including dandelion, Canada thistle and narrow-leaved hawk’s-beard
• MCPA ester tank-mix recommended to enhance broadleaf weed control
• mixes with Simplicity GoDRI, Axial, and Everest
• use Agral 90 surfactant with a Cirpreme and Simplicity GoDri tank-mix

Infinity FX (Bayer), SRP $12.52/ac (1 case treats 40 ac)

• co-pak of Infinity (Group 6+27) and fluroxypyr (Group 4) for broad-leaved weed control in wheat and barley
• provides enhanced control of cleavers, kochia and volunteer flax vs. Infinity
• mixes with Varro, Axial, Puma Advance, and Liquid Achieve

Travallas (FMC), SRP $11.70/ac (8 L jug treats 40 ac)

• Group 2 (actives from Refine SG and Ally) plus fluroxypyr (Group 4) for broad-leaved weed control in wheat and barley
• liquid formulation
• mixes with Axial, Simplicity, and Everest

Grass Herbicides

Everest 3.0 (Arysta)/Sierra 3.0 (Syngenta), SRP $20.33/ac/$22.10/ac (3.88 L jug treats 80 ac, wild oat rate)

• new formulations of Everest and Sierra for grass control in spring, durum and winter wheat
• same acres/jug, staging, and tank-mixes as Everest 2.0 and Sierra 2.0
• requires the addition of a non-ionic surfactant

Grass/Broadleaf Herbicides

Rexade (Corteva), SRP $30.95/ac (1 case treats 40 ac)

• co-pak of Rexade A – Simplicity GoDRI/Arylex and Rexade B – 2,4-D ester
• for broadleaf and grass control in spring and winter wheat
• an adjuvant is not required with Rexade

Luxxur (Bayer), SRP $19.80/ac (1 case treats 40 ac)

• Group 2 broadleaf active (tribenuron) co-packed with Group 2 grass active thiencarbazone (Varro)
• for broadleaf and grass weed control in spring wheat
• can be tankmixed with 2,4-D ester, MCPA ester, Buctril M, Infinity, Infinity FX, Octtain, Pixxaro, Paradigm, Prestige, Stellar, Trophy

Predicade (FMC), SRP $30.04/ac (1 case treats 40 ac)

• Group 2 broadleaf actives, tribenuron and thifensulfuron co-packed with Group 4 broadleaf actives fluroxypyr and MCPA ester plus the Group 2 graminicide thiencarbazone (Varro)
• for broadleaf and grass weed control in spring wheat

Adjuvants

HiActivate (WinField United), SRP $1.50/ac for 10 US gpa application        (10 L jug treats 1000 US gal)

• non-ionic spreader/activator in a low-foaming formulation
• 90% surfactant blend
• improves the properties of spray droplets for increased adhesion and wetting, resulting in enhanced pesticide absorption and efficacy

InterLock (WinField United), SRP $1.50 – $2.25/ac for 10 US gpa application (10 L jug treats 80 – 120 ac, 100 ac is common)

• crop-based adjuvant improves spray droplet coverage and helps droplets stay on target
• reduces the amount of fine particles in the spray pattern
• improves canopy penetration
• reduces drift and evaporation of spray droplets
• use higher rate for drift reduction
• works effectively with herbicides, fungicides, insecticides, dessicants and defoliants

Note:  Please refer to specific product labels before use.

• the current R/MR/MS/S (resistant, moderately resistant, moderately susceptible, susceptible) ratings as a % of Westar will remain the same, refers to minor gene resistance
• a label to identify the major resistance genes in the variety will be added i.e. Resistance A to Resistance P (see chart below). This is a voluntary label extension at this time.

e.g. Canterra CS2100 rating is “R – ACG”, which describes a resistant  variety with 3 resistance groups containing major resistance  genes Rlm1 (or LepR3), Rlm3 and RlmS, respectively

• growers can proactively manage blackleg by rotating to a variety with a different letter(s), and therefore a different source of resistance

The following exclusive WinField United products are available at Shur-Gro Farm Services, Munro Farm Supplies and South East Seeds:

Ascend SL™

 Product Type:  Ascend SL is a (soluble liquid) plant growth regulator (PGR) that contains an optimal combination of 3 plant growth regulators, which can result in vigorous early plant germination and emergence, a robust root system, and larger leaves and wider stems to help increase yield.  Ascend SL can be used as a seed treatment, in-furrow or as a foliar application.  Application can be made by ground or air.

Active ingredients:  Proprietary blend of cytokinin 0.090%, gibberellic acid 0.030% and indolebutyric acid 0.045%.  This combination of plant growth regulators promotes cell division and elongation in leaves and stems as well as vigorous root formation and elongation.

Use Rate:  Registered crops include alfalfa, canola, cereals, corn, dry beans and peas, soybeans and sunflowers.  A typical foliar use rate is 100 ml/ac (95 ac/9.46 L jug) and may be applied multiple (2-3) times in most crops.  SRP = $6.30/ac per application.

As a seed treatment for wheat, 260 ml/100 kg of seed is recommended.  Each jug will treat 134 bu of wheat seed.  SRP = $4.45/bu.

As an in-furrow treatment for corn, 177 ml/ac is recommended.  Each jug will treat 54 ac of corn.  SRP = $11.00/ac.

HiActivate™

Product Type:  Non-ionic spreader/activator adjuvant in a low-foaming formulation.  For use with most post-emergent crop protection products to improve the properties of spray droplets for enhanced efficacy.

Active ingredients:  90% blend of glycerol, sodium xylene sulfonate and alkyl phenol ethoxylate.

Use Rate:  Average use rate is 1 litre/100 US gallons or 0.25% v/v.  One 9.46 litre jug will treat 1000 US gallons of water.  SRP = $1.50/ac for 10 US gpa.

InterLock®

 Product Type:  Crop-based adjuvant that improves spray droplet coverage and helps droplets stay on target.  InterLock reduces the amount of fine particles in the spray pattern which helps to improve canopy penetration and reduce drift and evaporation of spray droplets. Works effectively with herbicides, fungicides, insecticides, dessicants and defoliants.

Active ingredients:  100% modified vegetable oil, polyoxyethylene sorbitan fatty acid ester, vegetable oil.

Use Rate:  As a deposition aid, one 9.46 L jug will treat 80-160 acres, SRP = $1.10 – $2.20/ac.  For drift reduction, one jug will treat 53-80 acres, SRP = $2.20 – $3.30/ac.  Use higher rates of InterLock at higher pressures or increased spray volume (within the 5 to 25 US gpa range).

In 2016, Hugh Beckie, Scott Shirriff and Julia Leeson of Agriculture Canada led a field survey of Manitoba to determine the incidence of weed resistance.  In late summer of that year, 150 randomly-selected fields were surveyed throughout Manitoba.  Before harvest, mature seeds from all residual weed species were sampled and subsequently plants were tested with Group 1 or 2 herbicides.  Survey results indicated:

• 68% of fields had a herbicide-resistant (HR) weed, this compared with 48% in 2008 and 32% in 2002
• 78% of fields had Group 1 resistant wild oats
• 43% of fields had Group 2 resistant wild oats
• 42% of fields had Group 1 and 2 multiple-resistant wild oats

This trend is being driven by a lack of new herbicide chemistries in the last 30 years, so growers use the same tools to manage their weed issues.  The inevitable consequence is a rise in weed resistance incidence.  Growers are also advised to be wary of HR broadleaf weeds.  Resistant populations of kochia, cleavers and chickweed to Group 2 herbicides are common.  Another weed of concern is glyphosate-resistant kochia, with Manitoba reporting its first few cases.  In the U.S. Midwest and southern states, herbicide resistant issues with the pigweed complex (Palmer amaranth, waterhemp, redroot and smooth pigweed) are causing major production challenges.  Hugh Beckie states, “It’s probably the number one global focal point for resistance now.”

Hugh Beckie has developed a “Top 10” list of the best management practices (BMPs) to address weed resistance.  Adopting these BMPs will improve weed control and slow the rate of weed resistance development:

• Crop diversity (rotation)
• Use competitive crops and practices that promote competitiveness
• Scout fields before and after herbicide applications, know your enemy
• Use multiple modes of action through herbicide mixtures and sequences
• Herbicide group rotation
• Rotate in-crop herbicide modes of action (selective mechanisms) in wheat
• Weed sanitation – border control, slow down the dispersal of HR weeds
• Site-specific (patch) weed management
• Strategic tillage – if, where, or when needed
• Accurate record-keeping of herbicides used and weeds present, invaluable reference

Please contact your local Shur-Gro, Munro, or South East Seeds agronomist to help plan an effective program to combat weed resistance.