Berries Production Guide

Blueberries
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Weeds

This section was updated - 06 September 2017

Good weed control is critical, especially in the establishment years, as weeds compete with the crop for water, light and nutrients and can seriously limit growth. Weeds can also provide shelter for field mice and encourage certain insects and diseases.

Prior to planting it is critical to control existing perennial weeds and brush. Glyphosate formulations such as Roundup or Touchdown effectively control tough weeds without leaving a soil residue.

Sawdust mulch will help to suppress annual weeds, but herbicides will also be necessary. Select a combination of herbicide treatments from the following pages based on soil type and knowledge of the major problem weeds in the field.

Do not apply residual herbicides such as Velpar, Sinbar, Chateau and simazine until plants become well established (6 months to a year after planting).

Note: Herbicide application rates are listed on pesticide labels and in the production guide for broadcast or total field coverage. If spraying a band over the row area only, then the treated area is only a portion of the whole field and rates must be reduced accordingly. For example, when spraying 1 m bands on rows 3 m apart, only one third of the field is treated. To avoid calculating areas each time you spray herbicides in bands, record the actual area sprayed in each of your fields. Also record the actual area sprayed by one sprayer tank.

BEFORE WEED EMERGENCE

Broadleaf seedling weeds Sencor 75 DF (75% metribuzin) 1.0 kg/ha (0.4 kg/acre)
  • Apply as a banded spray to the soil surface directed to the base of non-bearing blueberry bushes in a spray volume of 150 to 300 L water/ha (60 to 120 L/acre).
  • Apply preemergence to the weeds.
  • Do not use on soil with less than 2% organic matter.
  • Rainfall and/or overhead sprinkler irrigation is necessary to move the herbicide into the upper soil surface where weed seeds germinate.
  • Do not apply if heavy rainfall (more than 2.5 cm) is expected shortly after application.
  • Do not apply excessive irrigation (more than 2.5 cm) after application.
  • Triazine-resistant weeds will not be controlled.
  • Do not apply more than once per season.
  • Do not apply within 2 years of harvest.
Seedling broadleaf and grassy weeds Princep Nine-T (90% simazine) 2.5 to 3.75 kg/ha
(1.0 to 1.5 kg/acre)
  • Apply in early spring before weeds and grass emerge to control seedlings.
  • Use lower rate for coarse, sandy soil and higher rate for clay soils and soils high in organic matter content.
  • Apply in a minimum of 300 L/ha (120 L/acre) of water. • Do not apply to plantings less than a year old.
Seedling broadleaf and grassy weeds Sinbar 80W
(80% terbacil)
2.75 to 4.25 kg/ha
(1.1 to 1.7 kg/acre)
  • Apply in spring before weeds emerge to crops established at least one year.
  • Use the higher rate on organic and muck soils.
  • Do not apply to sandy soils or soils with less than 1% organic matter or to exposed roots of crop.
  • 5.5 L/ha (2.2 kg/acre) of Gramoxone may be tank-mixed with Sinbar if weeds have emerged.
  • Apply in a minimum of 200 L/ha (80 L/acre) of water.
  • Do not apply within 80 days of harvest.
  • Do not apply to plantings less than a year old.
Seedling broadleaf weeds Devrinol 50DF or Devrinol DF-XT
(50% napropamide)
9 kg/ha
(3.6 kg/acre)
  • Apply in fall through early spring (only once per season). Will not control shepherd's purse or lady's thumb. Not recommended for soils with over 10% organic matter.
  • Apply in enough water to get even distribution over the soil surface.
  • Do not apply to frozen ground.
  • If rainfall does not occur within 7 days for a spring or fall application or 2 days for a summer application, irrigate to wet the soil to a depth of 5-10 cm.
  • Do not apply within 70 days of harvest.
Seedling broadleaf weeds Devrinol 10G
(10% napropamide)

45 kg/ha
(18 kg/acre)

  • Apply in the fall through early spring prior to weed emergence (only once per season).
  • Will not control shepherd’s purse or lady’s thumb.
  • Requires mechanical incorporation, adequate irrigation or natural moisture for optimum results. The treatment must reach the zone of weed seed germination.
  • If rainfall does not occur within 7 days for a spring or fall application or 2 days for a summer application, irrigate to wet the soil to a depth of 5 to 10 cm.
  • Do not apply to frozen ground.
  • Do not apply within 70 days of harvest.
Seedling and perennial broadleaf weeds and grasses Casoron G-4 (4% dichlobenil) 175 to 225 kg/ha
(70 to 90 kg/acre)
  • Apply in the dormant period (late winter) when temperature is below 15o C. Casoron is volatile above this temperature so must be irrigated in immediately or have rains shortly after treatment at higher temperatures.
  • Do not apply the high rate more often than every other year.
Seedling broadleaf weeds Chateau WDG (51.1% flumioxazin)

280 to 420 g/ha (112 to 168 g/acre)

  • Apply in early spring before bud break and emergence of weeds.
  • Use the low rate on coarse textured soils with less than 5% organic matter and the higher rate on medium texture soils with less than 5% organic matter. Do not apply to fine-textured soils or to soils with more than 5% organic matter.
  • Use enough water to ensure good coverage of the soil surface.
  • Apply to well-drained soil as crop injury may occur from applications made to poorly drained soils and/or under cool, wet conditions.
  • At least 0.5 cm of rainfall or irrigation is necessary to activate the herbicide.
  • Do not apply after bud break unless using hooded or shielded application equipment to ensure spray drift will not come in contact with the crop.
  • Do not apply to crops established less than 2 years.
  • Do not apply more than twice in a growing season.
  • Do not make a second application within 30 days of the first spray.
  • Do not apply within 7 days of harvest.
Seedling broadleaf weeds and some grasses Authorithy (480 g/L sulfentrazone) 0.29 L/ha (0.12L/acre)
  • Apply as a broadcast spray or as a uniform band to the base of berry and beds in berries.
  • Apply a single spray in a minimum water volume of 100L/ha (40L/acre.
  • Apply to crops that have been established for one full growing season and are in good health and vigor.
  • Avoid direct or indirect spray contact to foliage and green bark (wrap trunk with nonporous wrap, grow tubes, or wax containers to keep spray solution off of green tissue).
  • At least 0.5 cm of rainfall or irrigation is necessary to activate the herbicide.
  • Do not apply in any type of soils with more than 6% organic matter.
  • Do not apply after petal fall unless a shielded sprayer is used.
  • Do not tank mix with Chateau herbicides (flumioxazin) or with other products containing sulfentrazone.
  • Do not apply within 3 days of harvest
Seedling grasses Dual Magnum or Dual II Magnum
(915 g/L S-metolachlor and R-enantiomer)
1.25 to 1.75 L/ha (0.5 to 0.7 L/acre)
  • Apply as a banded application to the base of plants in early spring before weed emergence.
  • Apply in 150 to 300 L /ha (60 to 120 L/acre) of water.
  • Avoid contact with the blueberry trunk and foliage or injury may occur.
  • Do not apply within 30 days of harvest.



 

EMERGED WEEDS
Annual Weeds Gramoxone
(200 g/L paraquat)

5.5 L/ha
(2.2 L/acre)

  • Apply thoroughly to cover weed and grass growth (up to 1100L/ha (440 L/acre) of water.
  • Apply as needed to burn off emerged vegetation but avoid spraying canes or emerging shoots as injury will occur.

Annual Weeds

(Between the rows only)
Aim EC (240 g/L carfentrazone-ethyl) 37 to 117 mL/ha (15 to 47 mL/acre)
  • Apply between the rows with a hooded sprayer to emerged weeds. Crop injury will occur if drift is allowed to come in contact with green stem tissue, leaves, blooms or fruit.
  • To improve control, apply with surfactants such as Agral 90 or Ag-Surf at 0.25% (0.25 L/100 L of water) or Merge at 1% (1 L/100 L of water).
  • Do not apply within 1 day of harvest.
Hard to control perennial weeds Casoron G-4
(4% dichlobenil)
225 kg/ha
(90 kg/acre) or 22.5 g/m2
  • High rate will suppress quackgrass, thistles, horsetail, bracken fern, etc.
  • Do not apply at this rate more often than every other year.
  • Apply in the dormant period (late winter) when temperature is below 15o C. Casoron is volatile above this temperature so must be irrigated in immediately or have rains shortly after treatment at higher temperatures.

Clover (red and white)



Vetch
Lontrel 360
(360 g/L clopyralid)

830 mL/ha
(340 mL/acre)



420 mL/ha
(170 mL/acre)
  • Apply when the weeds are actively growing but not within 45 days of harvest.
  • Avoid contact with crop foliage to prevent injury.
  • Apply in 100 to 200 L/ha (40 to 80 L/acre) of water.
  • Use the higher volume when weed density is high.
  • Apply no more than once per year.
Annual and perennial broadleaf weeds including red root pigweed, lamb's-quarters, creeping yellow cress Sandea (72.6 % halosulfuron

1-4 year old bushes:

35 to 47 g/ha  (14 to 19 g/acre)

bushes older than 4 years: 

35 to 70 g/ha (14 to 28 g/acre)

 

  • Apply as a broadcast application to the ground on either side of the row in a minumum of 140 L/ha (56 L/acre) of water.
  • If small weeds are present, tank-mix with a post-emergence herbicide to enhance the spectrum of broadleaf and grass control.
  • Contact with blueberry bushes should be avoided or temporary chlorosis of leaves will result.
  • Do not apply to plants established less than one year or to plants under stress.
  • Do not apply to Elliot plants established less than 4 years.
  • Do not apply to areas where water is known to pond for periods of time following rainfall.
  • Minimum of 45 days between applications.
  • Do not apply more than 140 g/ha (56 g/acre) per 12 month period.
  • Do not apply within 14 days of harvest.
Red root pigweed, barnyard grass and some other broadleaf and grassy weeds, quackgrass suppression Prism SG (25 % rimsulfuron)

60 g/ha          (24 g/acre)

  • Use on crops that have gone through at least one growing season and are in good health and vigour.
  • Apply to actively growing weeds.
  • Use a directed spray application to provide complete coverage of weeds while minimizing spray contact with blueberry plants.
  • Use a non-ionic surfactant such as Cittowett Plus, Agral 90 or Ag-Surf at 2 L/1000 L of spray mixture.
  • When applied as a banded treatment, Prism may be applied twice per year.
  • Do not apply within 21 days of harvest.

Red root pigweed, lamb's quarters, wild mustard and some other broadleaf weeds

Callisto 480 SC (480 g/L mesotrione) 300 mL/ha (120 mL/acre)
  • Apply in early spring before emergence of weeds or post-emergence up to the 8-leaf stage of weeds.
  • For post-emergence applications, add Agral 90 at 0.2 % (0.2 L/100 L of water).
  • Do not apply more than once per year.
  • Do not apply after bloom.
  • Do not apply within 60 days of harvest.
Broadleaf seedlings Goal 2XL (240 g/L oxyfluorfen) 1.0 L/ha (0.4 L/acre)
  • Apply as a directed spray when weeds are in the 2-4 leaf stage and actively growing.
  • Apply only once per year.
  • Do not apply within 50 days of harvest.
Grasses, broadleaf seedlings and perennials and woody weeds Velpar L (240 g/L hexazinone)


Velpar DF (750 g/kg hexazinone)
4 to 8 L/ha (1.6 to 3.2 L/acre)


1.28 to 2.56 kg/ha (0.5 to 1.0 kg/acre)
  • Apply before the weeds are 30 cm tall and prior to blueberry bloom.
  • Use lower rate on sandy soils or soils low in organic matter. Most effective under conditions of high temperature (above 27o C), high humidity and good soil moisture.
  • Apply in 100-300 L/ha (40 - 120 L/acre) of water.
  • Controls tough weeds such as trailing blackberry, hardhack, oxeye, daisy and goldenrod.
  • Do not re-enter treated areas within 48 hours of application.
  • Registered for use on Bluecrop variety only. Do not apply within 60 days of harvest.
Grassy and broadleaf weeds Ignite SN (150 g/L glufosinate ammonium)

2.7 to 5.0 L/ha

(1.1 to 2.0 L/acre)
  • Apply as a directed spray around the base of blueberry bushes in 330 to 1100 L/ha (130 to 440 L/acre) of water.
  • Do not allow spray to drift onto leaves or green bark as crop damage will occur.
  • A repeat treatment may be necessary to control new germination of annual weeds.
  • Do not make more than 2 applications per year.
  • Do not apply more than 6.7 L/ha (2.7 L/acre) total product in one season.
  • Do not apply within 14 days of harvest.
Quackgrass, perennial, and annual weeds Roundup
(356 g/L glyphosate)
2.8 to 5.6 L/ha
(1.1 to 2.3 L/acre)
  • Use as a directed or shielded spray using no more than 275 kPa pressure. Apply in 50 to 300 L/ha (20 - 120 L/acre) of water. Addition of a surfactant is required for water volumes above 150 L/ha (60 L/acre).
  • Do not let spray contact fruit, foliage, canes or exposed roots.
  • Apply only once per season and not within 30 days of harvest.
  • The listed rates are based on a formulation with 356 g/L glyphosate. There are many new formulations of glyphosate on the market with varying active ingredient concentrations. Be sure to check the label for application rates.
Quackgrass and annual grasses Centurion or Select (240 g/L clethodim)

190 to 380 mL/ha

(75 to 150 mL/acre)
  • Apply as a directed post emergence spray in at least 100 L/ha (40 L/acre) of water.
  • Use the low rate for annual grasses and the high rate for quackgrass.
  • Use in combination with 0.5-1.0% Amigo adjuvant.
  • Weeds should be in the 2 to 6 leaf stage.
  • Do not apply more than once per year.
  • Do not apply within 14 days of harvest.
Venture L
(125 g/L fluazifop- p-butyl)
2.0 L/ha
(0.8 L/acre)
  • Apply prebloom in the spring to actively growing quackgrass at the 3 to 5 leaf stage. A rate of 1.2 L/ha (0.49 L/acre) will control annual grasses (2 to 6 leaf stage).
  • Apply only once per season.
  • Apply in 100 to 300 L/ha (40 to 120 L/acre) of water. Use the higher volume when weed density is high.
  • Do not apply within 15 days of harvest.
  • Warning: women capable of bearing children should avoid exposure to Venture.
Poast Ultra
(450 g/L sethoxydim)
1.1 L/ha
(450 mL/acre)
  • Apply to actively growing quackgrass up to the 3 leaf stage (8 to 12 cm high). Merge should be added to all applications at a rate of 1% of water volume.
  • Apply in 50 to 200 L/ha (20 to 80 L/acre) of water.
  • Use the higher volume when weed density is high.
  • Maximum 2 applications per season
  • Allow a minimum of  14 days between applications
  • Do not apply within 1 day of harvest.
Yellow nutsedge Basagran (480 g/L bentazon) 1.75 L/ha
(0.7 L/acre)
  • Apply as a directed spray when nutsedge is 15 to 20 cm tall. Repeat application in 7-10 days, but do not apply more than twice per year.
  • Apply with 2.0 L/ha (0.8 L/acre) of Assist Oil Concentrate in 100 to 400 L/ha (40 to 160 L/acre) of water.
  • Do not apply within 25 days of harvest.
Broadleaf weeds Ipco 2,4-D 600 (560 g/L dimethylamine salt)

1.7 L/ha (0.7 L/acre)

  • Apply as a directed spray only (between the rows)  in early spring after weeds have emerged and are actively growing. Do not overspray.
  • Do not apply more than once per season.
  • Do not apply within 30 days of harvest.

 

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