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Green Bunching Onions

Last updated on September 18, 2024

Green bunching onions

Growing green bunching onions

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Varieties

Bunching

American type

Beltsville Bunching, Green Banner.

Japanese type

Ishikura, Kincho, Fukagawa, Ramrod, Kiyotaki Long White.

Pickling

Eclipse.

See your seed dealer for the most recent variety recommendations.

 

Germination

Germination will occur at temperatures from 8 to 30°C with the optimum range at 16° – 24° C.

 

Soils

A pH of 5.0 to 6.0 is suitable for organic soils but 6.5 to 7.0 is preferred for mineral soils.

When the pH is below the range considered suitable, lime should be applied and incorporated thoroughly to a depth of 15 cm or more.

A late summer green-manure crop of oats, plowed down or worked in, before the ground becomes too wet to work is beneficial. An application of ammonium nitrate when the green-manure crop is being turned in will help break down the material.

Soil for use in flats should have bone meal or phosphate added to it and should be sterilized before use, preferably in the early fall.

 

Fertilizer

A soil test is required to determine nutrient requirements. Phosphorus and potassium requirements are similar to onions. Use the Vegetable Production Guide: Nutrient Management (PDF) for recommendations based on soil test results.

Prior to transplanting or seeding, broadcast and incorporate 70 kg/ha (28 kg/acre) nitrogen and all the required phosphate and potash.

It may be necessary to side-dress the transplanted crop.

 

Seeding

Early crop

The early crop is seeded in flats and is germinated and grown to transplant size in greenhouses or cold frames. When ready the seedlings are planted in clumps in rows which are 30 to 37.5 cm apart.

Later crops

As soon as the soil can be worked seeding is done in the field by hand or with a Planet Junior type of seeder. Four to 7 rows are seeded per bed. Seed requirement is approximately 15 kg/ha (6 kg/acre).

 

Seed treatment

For control of Pythium damping off, use seed treated with Apron XL LS seed protectant. 

 

Storage

Green onions may be stored for 2 to 3 days. The quicker the field heat can be removed and the onions placed in storage the longer they will keep. The recommended temperature during storage is 0 to 7°C at 95% relative humidity.

 

Green bunching onion weed management

Weed control is important particularly during the early stages. If done by hand, extreme care has to be taken not to disturb or damage the young onion seedlings.

Chemical control may be done for the seeded crop by following the stale seed-bed technique found in the Vegetable Production Guide: Pest Management (PDF, 1.2 MB) or by using Dacthal W75 (chlorthal). See weed management tables below for instructions.

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Pre-emergence

Note:  there are currently no registered products for pre-emerge weed control in green bunching onions.

Pre-emergence: herbicide application rates
Product Rate PHI* Comments

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF).

 

Post-emergence

Post-emergence: herbicide application rates
Product Rate PHI* Comments

Venture L

(fluazifop-P-butyl & S-isomer)

Group 1

 barnyard grass (2-5 leaf stage):
0.8 L/ha (0.32 L/acre)

proso millet (2-5 leaf):
1.0 L/ha (0.4 L/acre)

foxtails (2-4 leaf):
1.4 L/ha (0.56 L/acre)

quackgrass (3-5 leaf):
2.0 L/ha (0.8 L/acre)

14
 

 

14
 

 

14
 

 

14
  • Annual bluegrass and broadleaved weeds are not controlled.
  • If 1.0 L/ha (400 mL/acre) or less is used, one repeat application may be applied using a 14 day interval.
  • At the higher rates only one application is permitted per season.
  • Apply in 50 to 200 L/ha (20 to 80 L/acre) water at 200 to 300 kPa.
  • Warning: Women capable of bearing children should avoid exposure to Venture.
  • Do not handle more than 50 kg a.i. (400 L product) per day.
  • Use a closed cab when applying more than 33 kg a.i. (264 L product) per day.
  • Observe a plantback interval of 12 months for crops not listed.
  • Do not re-enter treated area for 12 hours.

Poast Ultra

(sethoxydim)

Group 1

Note:  No longer produced

Annual grasses (incl. volunteer cereals):

320 mL/ha (130 mL/ac)

 

Annual grasses & quackgrass suppression:

470 mL/ha (190 mL/ac)

 

Quackgrass:

1.1 L/ha (445 mL/ac)		 30
  • Apply when annual weeds are in the 1 to 6 leaf stage and when quackgrass is in the 1 to 3 leaf stage.
  • Repeat using a 14 day application interval.
  • Do not apply more than 2 times per year.
  • Do not apply more than 1.1 L/ha (445 mL/ac) per season.
  • For control of annual grasses and quackgrass suppression, add Merge adjuvant using a rate of 0.5 - 1.0 L/ha (0.2 - 0.4 L/ac).
  • For control of quackgrass, add Merge adjuvant using a rate of 1.0 - 2.0 l/ha (0.4 - 0.8 L/ac).
  • Annual bluegrass is not controlled.
  • Apply in 50 to 200 L/ha (20 to 80 L/acre) of water at 240 kPa pressure..
  •  See label for water volume and pressure when weed infestations or crop canopies are dense.

Prowl H2O

(pendimethalin)

Group 3
Mineral soils:
2.37 L/ha
(1 L/acre)
 
Muck soils:
6.6 L/ha
(2.7 L/acre)

 

Apply in 200 L/ha (80 L/acre) of water
 30

Mineral soils:

  • Controls redroot pigweed.
  • Suppresses lamb's-quarters.
  • Destroy existing weeds before applying.
  • Apply once before weed emergence at the 2 to 3 true leaf stage of the crop.
  • Rainfall or irrigation within 7 days of application improves control.
  • Do not re-enter treated area for 24 hours.

Muck soils:

  • Planting depth must be a minimum of 2 cm when planting green bunching onions.
  • Controls barnyard grass, chickweed, lamb's-quarters and pigweed.
  • Apply between the loop stage and flag stage of green onions.
  • Should weeds develop, a shallow cultivation or rotary hoeing will generally result in better weed control.
  • Do not use on onions grown from sets.
  • Do not apply more than once during the season per field.
  • Do not apply more than one year in sequence.
  • In case of crop failure, land treated can be reseeded with dry bulb onions.
  • Carrots, direct-seeded lettuce and dry bulb onions may be planted into soil which was treated the previous year.
  • Do not re-enter treated area for 4 days for scouting, 7 days for hand-set irrigation and 15 days for hand weeding.

Aim EC

(carfentrazone-ethyl)

Group 14

 37 to 117 mL/ha
(15 to 47 mL/acre)

Apply in 100 L/ha (40 L/acre) of water		 1
  • Controls annual weeds.
  • Must be applied using hooded sprayers to weeds between the rows of the emerged crop.
  •  Use an adjuvant such as Agral 90 or Agral-Surf at 0.25% v/v (0.25 L/100 L of spray solution) or Merge at 1% v/v (1 L/100 L of spray solution).
  • Precaution:  crop injury will occur when spray drift is allowed to come in contact with green stem tissue or leaves.
  • Apply only once per growing season.

Frontier Max

(dimethenamid - P)

Group 15
Mineral soils:
963 mL/ha
(389 mL/acre)
 
Muck soils:
1.29 L/ha
(522 mL/acre)

Apply using 200 to 300 kPa spray pressure. 
 30
  • Apply alone as a single application at the loop stage only and before weeds emerge.
  • Use low rate on mineral soils to control red root pigweed and nightshade
  • Use high rate on muck soils to reduce competition from redroot pigweed and to suppress yellow nutsedge.
  • Application prior to loop stage can cause significant crop injury including possible stand reduction.
  • Avoid application under cool conditions.
  • If crop failure occurs, do not replant potato, dry bulb shallots or onions until the following year.
  • On mineral soils, observe a plantback interval (PBI) for 100 days for cereals other than corn and 11 months for all other crops not listed.
  • On muck soils, observe a PBI of 11 months for carrots, transplanted celery and onions.  See label PBI precautions for other crops grown on muck soils.
  • Early crop development may be delayed for carrots and celery used in rotation, but this should not have a negative development on yield.
  • Do not enter treated area for 24 hours.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF, 421KB)
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF, 703KB)

 

Green bunching onion insect management

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Leafminer

Please refer to the Vegetable Production Guide: Pest Management (PDF, 1.2 MB) for guidance on controlling leafminers.

Chemical control of leafminer
Product Rate PHI Comments

Coragen

(chlorantraniliprole)

Group 28

250 to 375 mL/ha
(101 to 152 mL /acre)

Apply in 100 L/ha (40 L/acre) of water

1
  • Do not apply for a minimum of 60 days following an in-furrow or soil application or planting of seed pieces treated with any Group 28 insecticide.
  • Repeat at 5 day intervals.
  • Do not apply more than 4 times per season.
  • Do not make more than 2 successive applications per generation of loopers.  The following application must be with an effective non-Group 28 insecticide.
  • Do not apply more than 1.125 L/ha (455 mL/ac) per season.
  • Do not re-enter treated area for 12 hours.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF, 421KB)
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF, 703KB)

 

Onion maggot

Small, grayish fly, smaller than a house fly, lays eggs at base of plants. Small, white maggots feed in onion bulbs. If attack occurs early, plants may be killed. If attacked later, plants live, but the bulbs are misshapen and contain maggots. Secondary rot often occurs.

Monitoring

Monitoring with white sticky traps is useful to detect both onion maggot flies and onion thrips. With this information, control can be achieved with fewer sprays. Onion flies, however, cannot be properly identified without the use of a dissecting microscope and considerable expertise.  Commercial scouting services are recommended for accurate identification.

Control

Foliage treatment

Growers should apply foliage sprays at 10 day intervals beginning April 15. Sprays are most effective when applied in the morning (8 to 10 a.m.) or early evening (6 to 9 p.m.). Use sufficient water to thoroughly wet plants and soil. 

Chemical control of onion maggot
Product Rate PHI* Comments

Mako

(cypermethrin)
 
Group 3

175 mL/ha
(70 mL/acre)

Apply in 110 L/ha (44 L/acre) of water

 3
  • Use as a foliar spray for fly control after an at-plant soil treatment has been made.
  • Repeat using 7 to 10 day intervals.
  • Maximum of 3 applications per season.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • If the field slopes downward to water, construct and maintain a vegetative filter strip.  Check label for details.
  • Observe a 30 day plantback interval for crops not listed.
  • Do not re-enter treated area for 12 hours.

Up-Cyde 2.5 EC

(cypermethrin)
 
Group 3

280 mL//ha
(115 mL/acre)

Apply in 100 to 500 L/ha (40 to 200 L/acre) of water

 3
  • Use as a foliar spray for fly control.
  • Maximum of 3 applications per season.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • If the field slopes downward to water, construct and maintain a vegetative filter strip.  Check label for details.
  • Observe a 30 day plantback interval for crops not listed.
  • Do not re-enter treated area for 12 hours.

Scorpio Ant and Insect Bait

(spinosad)
 
Group 5

25 50 kg//ha
(10.1 to 20.2 kg/acre)

 3
  • Suppression only of larvae.
  • Apply using a spreader suitable for granulars or by hand.
  • Make a broadcast application on the soil near the base of the seedlings directly after transplanting or 7 to 10 days after seeding, or as soon as seed germinates.
  • Reapply after heavy rain or watering or as the bait is consumed, or every 4 weeks.
  • Do not apply more than 3 times per year.
  • Works better when soil is moist but with little or no standing water.
  • Do not place bait in piles.
  • Toxic to bees and certain beneficials.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF, 421KB)
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF, 703KB)

 

Thrips

Thrips are very small (1 mm), slender, yellowish to brown insects which may be winged or wingless. They rasp and puncture plant tissue, causing silvery areas on leaves.

Control

Good weed control will keep thrips populations low. When thrips appear, apply three foliage sprays at 10 day intervals. Use one of the insecticides recommended in the Onion Maggot section and note the restrictions regarding days to harvest. Use sufficient water to thoroughly wet the plants.

Chemical control of thrips
Product Rate PHI* Comments

Mako 

(cypermethrin)
 
Group 3

175 mL/ha
(70 mL/acre)

Apply in 100 to 500 L/ha (40 to 200 L/acre) of water

3
  • Repeat using 10 day intervals.
  • Maximum of 3 applications per season.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • If the field slopes downward to water, construct and maintain a vegetative filter strip.  Check label for details.
  • Observe a 30 day plantback interval for crops not listed.
  • Do not re-enter treated area for 12 hours.

Up-Cyde 2.5 EC

(cypermethrin)
 
Group 3

280 mL//ha
(115 mL/acre)

Apply in 100 to 500 L/ha (40 to 200 L/acre) of water

3
  • Repeat using 10 day intervals.
  • Maximum of 3 applications per season.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • If the field slopes downward to water, construct and maintain a vegetative filter strip.  Check label for details.
  • Observe a 30 day plantback interval for crops not listed.
  • Do not re-enter treated area for 12 hours.

Decis 5 EC

(deltamethrin)

Group 3
 200 mL/ha
(80 mL/acre)

Apply in 200 to 500 L/ha (80 to 200 L/acre) water 		5
  • Apply mid-season at the proper thrips threshold. (Use the advice of a crop monitoring service).
  • Do not apply more than once per season.
  • For soils with high organic matter content (muck soils), apply prior to August 1.

Delegate WG

(spinetoram)

Group 5

200 to 336 g/ha
(81 to 136 g/acre)

Apply in 300 to 500 L/ha (120 to 200 L/acre) of water

 3
  • Suppression only.
  • For optimal performance, final solution pH should be in the range of 6 to 8.
  • Apply at egg hatch or to small larvae.
  • Ensure spray solution penetrates to leaf axils.
  • Repeat at 7 to 10 day intervals.
  • Maximum of 3 applications per year.
  • Toxic to bees. Avoid spraying when bees are foraging.
  • Do not re-enter treated area for 12 hours.

Entrust 80

(spinosad)
 
Group 5
 
Used in organics

 

131 to 158 g/ha
(53 to 64 g/acre)

Apply in 300 to 500 L/ha (120 to 200 L/acre) of water

 3
  • Suppression only.
  • Apply when onion thrips first appear targeting egg hatch or small nymphs.
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than three times per season.
  • Highly toxic to bees.  Do not apply if bees are visiting the area.  
  • Harmful to parasitoids and predatory mites.  Slightly harmful to foliage-dwelling predators.
  • Entrust products are OMRI-USA listed.  Check with your certification body before using in an organic operation.
  • Do not re-enter treated area until residues have dried.

Entrust SC

(spinosad)
 
Group 5
 
Used in organics

437 to 527 mL/ha (177 to 213 mL/acre)

Apply in 300 to 500 L/ha (120 to 200 L/acre) of water

 3
  • Suppression only.
  • Apply when onion thrips first appear targeting egg hatch or small nymphs.
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than three times per season.
  • Highly toxic to bees.  Do not apply if bees are visiting the area.  
  • Harmful to parasitoids and predatory mites.  Slightly harmful to foliage-dwelling predators.
  • Entrust SC (PCP# 30382) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.
  • Do not re-enter treated area until residues have dried.

Success

(spinosad)

Group 5

218 to 262 mL/ha
(88 to 106 mL/acre)

Apply in 300 to 500 L/ha (120 to 200 L/acre) of water

 3
  • Suppression only.
  • Apply when onion thrips first appear targeting egg hatch or small nymphs.
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than three times per season.
  • Highly toxic to bees.  Do not apply if bees are visiting the area.  
  • Harmful to parasitoids and predatory mites.  Slightly harmful to foliage-dwelling predators.
  • Do not re-enter treated area until residues have dried.

Agri-Mek 1.9% EC

(abamectin)
 
Group 6

600 to 1200 mL/ha
(245 to 485 mL/acre)

Apply in 200 L/ha (80L/acre) of water

 7
  • Repeat at 7 day intervals.
  • Do not apply more than 4 times per season.
  • Highly toxic to bees exposed to direct treatment , drift or residues from blooming plants.
  • Do not re-enter for 13 days for hand weeding, 4 days for hand-set irrigation, 1 day for thinning and 12 hours for all other activities.

Agri-Mek SC

(abamectin)
 
Group 6 

135 to 270 mL/ha
(55 to 109 mL/acre)

Apply in 200 L/ha (80L/acre) of water

Use with 0.25 to 0.5% v/v non-ionic surfactant

 7
  • Repeat at 7 day intervals.
  • Do not apply more than 4 times per season.
  • Highly toxic to bees exposed to direct treatment , drift or residues from blooming plants.
  • Do not re-enter for 13 days for hand weeding, 4 days for hand-set irrigation, 1 day for thinning and 12 hours for all other activities.

Movento 240 SC

(spirotetramat)

Group 23

365 mL/ha
(150 mL/acre)

Apply in 200 L/ha (80 L/acre) of water		 7
  • Controls Onion Thrips (larvae).
  • Repeat at 7 day intervals.
  • Do not apply more than twice per season.
  • Maximum allowed per crop season: 730 mL/ha (295 mL/acre).
  • Movento 240 SC should be used with one of the following adjuvants: non-ionic (eg. Agral 90 or Ag-Surf) or methylated seed oil (eg. Hasten).
  • Reduction in numbers of thrips larvae may take 3 to 4 days after application.
  • Do not enter treated area for 12 hours.
  • Toxic to bees.  Do not apply when flowering weeds are present.

Exirel

(cyantraniliprole)

Group 28

1000 to 1500 mL/ha
(405 to 605 mL/acre)

Apply in 200 L/ha (80 L/acre) of water

1
  • Suppression only.
  • Do not make more than 4 applications per growing season.
  • Repeat at 5 day intervals.
  • Do not apply more than 4.5 L/ha (1.8 L/acre) per season.
  • Use with an adjuvant such as Hasten NT at a rate of 0.25% v/v or MSO Concentrate with Leci-Tech at a rate of 0.5% v/v.
  • Toxic to bees and certain beneficial insects.  Apply early in the morning or late in the evening when bees are not active.
  • Note:  Do not tank-mix or apply in sequence with strobilurin-, copper- or captan-containing fungicides.
  •  Observe a plantback interval of 30 days for legume vegetables, cereals, grass, crop group 1A (inlcuding beets, carrots, radish, parsnip, turnip) and crop group 2 (inlcuding beet greens and turnip greens). 
  • Observe a plantback interval of 1 year for crops not on this label.
  • Do not enter treated area for 12 hours.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF, 421KB)
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF, 703KB)

OMRI-USA = Organic Materials Review Institute of USA

OMRI-Canada = Organic Materials Review Institute of Canada

 

Green bunching onion disease management

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Botrytis blast or leaf blight

Small white spots appear on leaves later coalescing into elongated blotches. Grey mould may appear on the dead tissue under wet conditions.

Control

  • Avoid high rates of nitrogen fertilizer.
  • Avoid sprinkler irrigation if blast is apparent in a crop.
  • Apply Bravo 500 (see table below for instructions).

Chemical control of botrytis blast or leaf blight
Product Rate PHI* Comments

Serenade Opti

(Bacillus subtilis)
Used in organics
 Leaf Blight:
(700 to 1000 g/acre)		 0
  • Suppression only.
  • Also suppresses Botrytis Neck Rot.  Check label.
  • Repeat at 7 to 10 day intervals.
  • Serenade Opti (PCP# 31666) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Serenade Max

(Bacillus subtilis)
 
Note:  no longer produced.

Used in organics
 Leaf Blight:
(1.2 to 1.8 kg/acre)		 0
  • Suppression only.
  • Also suppresses Botrytis Neck Rot.  Check label.
  • Repeat at 7 to 10 day intervals.
  • Serenade Max (PCP# 28549) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Cueva

(copper octanoate)

Group M1

Used in organics

 Use a 0.5% to 2% solution at 470 to 940 L/ha (190 to 380 L/acre) 1
  • For a 0.5% solution, mix 1 part Cueva to 200 parts water.
  • For a 2% solution, mix 1 part Cueva to 50 parts water.
  • Repeat at 7 to 10 day intervals.
  • Repeat at 5 to 7 day intervals following heavy rain or when disease pressure is high.
  • Do not make more than 15 applications per year.
  • Time applications so that 12 hours of dry weather follow application.
  • Cueva products (PCP# 31825) are OMRI-Canada listed.  Check with your certification body before using in an organic operation.
  • Do not re-enter treated area for 4 hours.

Bravo 720

(chlorothalonil)

Group M5		 1.7 to 3.3 L/ha
(0.7 to 1.3 L/acre)		 14
  • Controls Botrytis leaf blight.
  • Repeat using a 7 day interval.
  • Do not make more than 2 applications per year.
  • A closed transfer system must be used when mixing and loading.
  • Check the label for PPE requirements while mixing and handling.
  • A vegetative buffer strip is required between the field edge and adjacent, downhill aquatic habitats.  Check label for details.
  • Do not re-enter for 6 days for hand-weeding; 1 day for scouting and 12 hours for all other activities.

Bravo ZN

(chlorothalonil)

Group M5

 2.4 to 4.8 L/ha
(1.0 to 1.9 L/acre)		 14
  • Controls Botrytis leaf blight.
  • Repeat using a 7 to 10 day interval.
  • Do not apply more than 2 times per year.
  • A closed transfer system must be used when mixing and loading Bravo ZN.
  • When using Bravo ZNC, mixers and loaders cannot handle more than 680 L of product per day.
  • Check the label for PPE requirements while mixing and handling.
  • A vegetative buffer strip is required between the field edge and adjacent, downhill aquatic habitats.  Check label for details.
  • Do not re-enter for 6 days for hand-weeding; 1 day for scouting and 12 hours for all other activities.

Bravo ZNC

(chlorothalonil)

Group M5

Echo 720

(chlorothalonil)

Group M5

 1.7 to 3.3 L/ha
(0.7 to 1.3 L/acre)		 14
  • Controls Botrytis leaf blight.
  • Repeat using a 7 to 10 day interval.
  • Do not apply more than 2 times per year.
  • If handling more than 340 kg a.i. in one day, mixers and loaders must use a closed system.
  • Do not re-enter for 6 days for hand-weeding; 1 day for scouting and 12 hours for all other activities.

Lance WDG

(boscalid)

Group 7

 475 g/ha (190 g/acre)

Apply in 100 L/ha (40 L/acre) of water 		7
  • Repeat at 7 to 14 day intervals.
  • Maximum of 6 applications per season.
  • Only 2 sequential applications before alternating to a fungicide with a different mode of action.
  • Do not enter treated area for 12 hours.
  • For crops not on the label, observe a plant back interval of 14 days.

Cantus WDG

(boscalid)

Group 7		 475 g/ha (190 g/acre)

Apply in 100 L/ha (40 L/acre) of water 		7
  • Repeat at 7 to 14 day intervals.
  • Maximum of 6 applications per season.
  • Only 2 sequential applications before alternating to a fungicide with a different mode of action.
  • Do not enter treated area for 12 hours.
  • For crops not on the label, observe a plant back interval of 14 days.

Sercadis

(fluxapyroxad)

Group 7		 333 to 666 mL/ha
(135 to 270 mL/acre)

Apply in 100 L/ha (40 L/acre) of water		 7
  • Repeat at 7 to 14 day intervals.
  • Do not make more than 3 applications per season.
  • Do not apply more than 2.0 L/ha (809 mL/acre) per season
  • No more than 2 consecutive applications before alternating with a fungicide with a different mode of action.
  • Do not enter treated area for 12 hours.
  • For crops not listed, observe a plant back interval of 1 year.

Switch 62.5 WG

(cyprodinil & fludioxonil)

Group 9 &12

 775 to 975 g/ha
(314 to 395 g/acre)

Apply in 200 L/ha (80 L/acre) of water 		7
  • Repeat using a 7 to 14 day application interval.
  • Do not make more than 3 applications per season.
  • Do not enter treated area for hand weeding for 3 days, and for all other activities do not re-enter for 12 hours.
  • Do not enter treated area for 12 hours.

Scala SC

(pyrimethanil)

Group 9		 1.0 L/ha
(400 mL/acre)

Apply in 300 L/ha (121 L/acre) of water		 7
  • Do not enter treated area for 24 hours for hand thinning or 12 hours for all other activities.
  • Apply at 7 to 14 day interval.
  • Maximum application of 6 L/ha (2.4 L/acre) per season.
  • To control leaf blight: Tank mix with Bravo ZN.  Check label for directions.
  • Do not enter treated area for 24 hours for hand thinning or 12 hours for all other activities.

Acapela

(picoxystrobin)

Group 11

0.6 to 0.88 L/ha
(240 to 400 mL/acre)

Apply in 110 L/ha (45 L/ac) of water

 0
  • Suppression only.
  • Also controls Botrytis neck rot.  Check label for rate.
  • Repeat using a 7 to 14 day interval.
  • Do not apply more than 2.63 L/ha (1.06 L/ac) per season.
  • Do not make more than 2 sequential applications before switching to a fungicide that has a different group number.
  • Observe a plantback interval of 10 months for crops not listed on the label.
  • Toxic to earthworms and to certain beneficial insects.
  • Do not re-enter treated area for 12 hours.

Pristine WG

(boscalid & pyraclostrobin)

Group 7 & 11		 1.0 to 1.3 kg/ha
(400 to 520g/acre)		 7
  • Repeat at 7 to 14 day intervals.
  • Do not apply more than 6 times per season.
  • Do not make sequential applications when suppressing downy mildew, but follow up 5 to 7 days later using a fungicide from a different group.
  • Do not enter treated areas for thinning for 3 days. For all other activities, do not enter treated areas until residues have dried.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF, 421KB)
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF, 703KB)

OMRI-Canada = Organic Materials Review Institute of Canada 

 

Downy mildew

This fungus, which overwinters in trash, first appears as yellowish spots on the upper halves of leaves which are later covered by a purplish, fuzzy mildew. The disease increases rapidly under conditions of high humidity.

Control

  • Practise sanitation and rotation. Cull piles with onions growing on them are an important source of inoculum.
  • Avoid planting spring-seeded onions near overwintering or transplanted onions or near windbreaks.
  • Keep cultivations to a minimum and cultivate preferably when the leaves are dry.
  • Southport White Globe has resistance.
  • Spray every 7 to 14 days commencing June 1 for transplanted crops or June 15 for spring-seeded crops with the products listed in the table below.

Chemical control of downy mildew
Product Rate PHI* Comments

Serenade Opti

(Bacillus subtilis)
Used in organics
 1.7 to 3.3 kg/ha
(700 to 1300 g/acre)		 0
  • Suppression only.
  • Also suppresses Botrytis Neck Rot. Check label.
  • Repeat at 7 to 10 day intervals.
  • Serenade Opti (PCP# 31666) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Serenade Max

(Bacillus subtilis)
 
Note:  no longer produced.

Used in organics
 3.0 to 6.0 kg/ha
(1.2 to 2.4 kg/acre)		 0
  • Suppression only.
  • Also suppresses Botrytis Neck Rot. Check label.
  • Repeat at 7 to 10 day intervals.
  • Serenade Max (PCP# 28549) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Cueva

(copper octanoate)

Group M1

Used in organics

 Use a 0.5% to 2% solution at 470 to 940 L/ha (190 to 380 L/acre) 1
  • For a 0.5% solution, mix 1 part Cueva to 200 parts water.
  • For a 2% solution, mix 1 part Cueva to 50 parts water.
  • Repeat at 7 to 10 day intervals.
  • Repeat at 5 to 7 day intervals following heavy rain or when disease pressure is high.
  • Do not make more than 15 applications per year.
  • Time applications so that 12 hours of dry weather follow application.
  • Cueva products (PCP# 31825) are OMRI-Canada listed.  Check with your certification body before using in an organic operation.
  • Do not re-enter treated area for 4 hours.

Copper oxychloride 50

(copper oxychloride)

Group M2		 3.0 kg/ha
(1.2 kg/acre)

Apply in 500 L/ha (200 L/acre) of water		 1
  • Start applications in mid-June for spring seeded crops.
  • Repeat at 10 to 14 day intervals.
  • Do not make more than 6 applications per year.
  • Do not re-enter treated area for 48 hours.

Ridomil Gold MZ 68WG

(metalaxyl-M & S-isomer/mancozeb)

Group 4 & M3

2.5 kg/ha            (1.0 kg/ac)

 

Use sufficient water to ensure thorough coverage at 275 kPa

 14
  • Treat crop before the outbreak of disease.
  • Repeat at 7 day intervals.
  • Do not make more than 3 applications per season.
  • When changing to a contact fungicide, apply the contact fungicide within 10 days of the last Ridomil Gold MZ 68WG application.
  • May be toxic to bees.  Avoid treatment when bees are foraging in the treatment area in ground cover containing blooming weeds.
  • Check label for PPE requirements, particularly when handling more than 547 kg of product per person per day.
  • For hand weeding, do not enter treated area for 1 day.  For all other activities, do not enter treated area for 12 hours. 

Quadris Top

(azoxystrobin/ difenoconazole)

Group 11 & 3

710 to 1000 mL/ha
(290 to 400 mL/acre)

Apply in 150 L/ha (60 L/acre) of water.

 7
  • Repeat at 7 to 14 day intervals.
  • Do not apply more than 3 times per year.
  • Do not re-enter treated areas for 12 hours.
  • Observe a plant back interval of 60 days for crops not listed on this label or the Inspire label. 

Pristine WG

(boscalid & pyraclostrobin)

Group 7 & 11		 1.0 to 1.3 kg/ha
(400 to 520g/acre)		 7
  • Suppression only.
  • Repeat at 7 to 14 day intervals.
  • Do not apply more than 6 times per season.
  • Do not make sequential applications when suppressing downy mildew, but follow up 5 to 7 days later using a fungicide from a different group.
  • Do not enter treated areas for thinning for 3 days. For all other activities, do not enter treated areas until residues have dried.

Reason 500SC

(fenamidone)

Group 11		 400 mL/ha
(160 mL/acre)		 7
  • Suppression only.
  • Repeat at 5 to 10 day intervals.
  • Do not apply more than 4 times per year.
  • Do not apply more than 1600 mL/ha (648 mL/ac) per growing season.
  • Do not enter treated area until residues have dried.

Cabrio EG

(pyraclostrobin)

Group 11		 560 to 840 kg/ha
(220 to 340 g/acre)

Apply in 225 L/ha (90 L/acre) of water		 7
  • Repeat at 10 day intervals.
  • Do not make more than 3 applications per season.
  • Do not enter treated area for thinning for 3 days and for all other activities, do not re-enter for 12 hours.
  • Do not use treated crops for feed.

Torrent 400SC

(cyazofamid)

Group 21

0.20 L/ha (80 mL/acre)

Apply in 200 to 600 L/ha (80 to 240 L/acre) of water.

 0
  • Tank-mix with a non-ionic or organosilicone surfactant such as Sylgard 309 at the manufacturer's label recommendations.
  • Repeat using a 7 to 10 day interval.
  • Do not apply more than 6 times per crop per year.
  • Observe a plantback interval of 30 days for crops not listed.
  • Do not enter treated area for 12 hours.

Aliette WDG

(fosetyl-aluminum)

Group 33

2.8 kg/ha
(1.1 kg/acre)

Apply in 150 L/ha (60 L/acre) of water

 7
  • Do not make more than 5 applications per year.
  • Do not use within one week of a copper application and do not tank mix with copper compounds.
  • May cause phytotoxicity when mixed with adjuvants which enhance pesticide penetration.
  • Do not enter treated areas for 12 hours.

Phostrol

(mono- and dibasic sodium, potassium, and ammonium phosphites)
 
Group 33
2.9 to 4.3 L/ha (1.2 to 1.7 L/acre)
 
Apply in 225 L/ha (90 L/acre) of water.
 0
  • Suppression only.
  • Repeat using a 7 to 14 day application interval.
  • Do not make more than 7 applications per season.
  • Do no re-enter treated area for 12 hours.

Forum

(dimethomorph)
 
Group 40

450 mL/ha
(182 mL/acre)

Apply in 200 L/ha (80 L/acre) of water.

 0
  • Suppression only.
  • Apply as a tank mix with another fungicide registered for downy mildew. Observe most restrictive directions including rate, PHI and re-entry interval.
  • Repeat using a 5 to 7 day spray interval.
  • Maximum of 5 applications per season.
  • Do not make more than 2 sequential applications before alternating to another non-group 40 fungicide for at least 1 application.
  • Do not handle more than 81 L per day.
  • Do not re-enter treated area for 12 hours.

Zampro

(ametoctradin & dimethomorph)

Group 40 & 45

 1.0 L/ha
(400 mL  /acre)

Apply in 200 L/ha   (80 L/acre) of water. 		0
  • Repeat at 5 to 7 day intervals.
  • Do not apply more than 3 times per season.
  • Use a spreading/penetrating adjuvant.
  • Do not re-enter treated area for 12 hours.
  • Observe a plantback interval of 30 days for all crops not on the label.

Orondis Ultra

(oxathiapiprolin & mandipropamid)

Group 49 & 40

0.4 L/ha
(160 mL  /acre)

Apply in 100 L/ha (40 L/acre) of water.

 7
  • Apply with a penetrating surfactant.
  • Repeat at 7 to 10 day intervals.
  • Do not make more than 4 applications per crop.
  • Do not make more than 2 consecutive applications before switching to a non-Group 49 & 40 fungicide.
  • When 3 or more fungicide applications are made, do not use in more than 33% of the applications.  Where a total number of applications is less than 3, make no more than one application of Orondis Ultra.
  • Observe a plantback interval of 30 days for tuberous and corm vegetables (Subgroup 1C) and other crops not listed.  Observe a PBI of 180 days for legume vegetables, except succulent peas.
  • Do not re-enter treated area for 12 hours.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF, 421KB)
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF, 703KB)

OMRI-Canada = Organic Materials Review Institute of Canada 

 

Onion smut (Urocystis)

Young leaves are swollen and dark in colour, eventually breaking open to release powdery black spores. Seeded onions are susceptible to infection in the very early stages from spores in the soil. Transplanted crops are not susceptible. Failure to control smut will result in a continual buildup of the fungus in the soil until it may become impossible to grow onions successfully.

Control

Pro Gro seed treatment usually gives satisfactory control.

In fields with a minor smut problem, the Pro-Gro seed treatment or Thiram granular treatments may be adequate. The infection period for smut is relatively short from about the second day after germination until the seedling is in its first leaf. It is critical that the seed and seedling be protected through this period. Use at least one of the following:

Pro-Gro seed treatment at the rate of 25 g/kg of seed. Apply to Methocel-treated seed before any other insecticide, fungicide or coating is added:

Preparation and application of the sticker

  1. Sprinkle Methocel A15 in water at the rate of 50 g/L to make up a 2% solution. Do not stir. Let stand overnight or longer in a cold area until the material is dissolved.
  2. Place the seed in a container which can be rotated or shaken and slowly add 60 mL of the 2% solution per kilogram of seed. Mix until the seed is uniformly coated and shining. If necessary, add more of the solution, until this condition is achieved.

Application of fungicide for smut control

Slowly add Pro Gro at the rate of 25 g/kg of seed. Mix well to ensure even distribution. Do not mix with bare hands.

Other control methods

  • Set out healthy transplants (smut does not infect transplants)
  • Seed fields with a previous history of smut as late as possible as there will be less infection under conditions favourable to rapid seed germination and seedling growth
  • See table below for registered products
 

Rust (Puccinia)

Powdery, yellow to orange or reddish-brown pustules appear on leaves, usually in mid-summer, making the crop unmarketable. Spores can blow on wind currents for long distances. In Coastal B.C., the most common species of rust infects only plants in the onion family, such as onions, garlic, leeks and chives. Occasionally, asparagus rust may also infect onions. The most common sources of infection are nearby home gardens and volunteer plants or wild asparagus.

Control

  • Destroy cull onions which may sprout and become infected.
  • Destroy volunteer onions in the field and wild asparagus in ditchbanks.
  • Follow a two to three year crop rotation with plants not in the onion family.
  • Try to locate and remove the source of spores. Check nearby vegetable gardens, onion or asparagus fields, or weedy areas upwind for infected plants. If this is not possible, it may be necessary to move the onion field to another location. This should be at least one kilometer away from the source of the spores, or as far away as possible.
  • Ridomil MZ 68 WP applied for downy mildew should also help to control rust, if applied when the first few pustules are seen or before, and repeated on a 7-10 day schedule.
 

Tip dieback

Tip dieback may affect whole fields of both green bunching onions and young bulb onions. It is believed to be a physiological disorder resulting from environmental stress such as high levels of ozone in the atmosphere.

Control

No control is known for this poorly understood disorder. Varieties appear to differ in susceptibility. If good records are kept of its occurrence from year to year, it may be possible to avoid the more susceptible varieties. Sprays for Botrytis blast and downy mildew may help to prevent invasion of the dead leaf tissue by secondary fungi which are capable of causing further leaf injury.

 

White rot

(Sclerotium cepivorum)

This serious disease is now well established in the Southern Interior, Cloverdale and Burnaby onion-growing areas. Infected plants show yellowing and die-back of the leaf tips, progressing downward to the roots. Bulbs develop watery decay, eventually covered with white, fluffy, fungus growth dotted with masses of small black sclerotia.

Control

Once established in a field, white rot builds up whenever onion or garlic is grown. The sclerotia can persist in the soil for 10 years or more. Control is difficult and costly so utmost precautions should be taken to prevent spread into new fields. Avoid growing onions in fields known to be infested if at all possible. Wash down equipment in a safe area when moving from an infested to a clean field. Dispose of diseased onions, trash and containers in such a way as to minimize the chances of contaminating new areas. Take steps to reduce the danger of flood waters carrying diseased onions and sclerotia from field to field. It is especially important to avoid contaminating clean land with infected transplants or sets which were grown on infested land.

 

Root rot

RootShield WP (Trichoderma harzianum Rifai strain KRL-AG2) is a biological fungicide for the suppression of Root Rot in greenhouse vegetable transplants.  When applied to transplants, greenhouse planting mix or soil, the product grows into plant roots as they develop to protect roots  against Pythium, Rhizoctonia and Fusarium. 

Suppression

  • Suspend RootShield WP using a spray volume of 30 to 45 g/100 L and apply at the rate of 55 to 110 g per cubic metre (loose) of greenhouse potting mix, soil or planting beds. 
  • Apply using hand-held backpack or ground spray equipment. 
  • Becomes active when soil temperatures are above 10 degrees C and is not effective while soils remain cold.
  • More effective at suppression of root rot in neutral or acidic soils.  
  • Should be used within 12 months of the date of manufacture.  
  • Contains the allergens wheat and sulfites.

RootShield WP is used in organics.  It is OMRI-USA listed.  OMRI-USA = Organic Materials Review Institute of USA.  Check with your certification body before using in an organic operation.

 

Suppression of Stemphyliium leaf blight

Chemical suppression of Stemphyliium leaf blight
Product Rate PHI* Comments

Aprovia

(benzovindiflupyr)

Group 7
 750 mL/ha
(300 mL/acre)

Apply in at least 150 to 600 L/ha (60 to 240 L/acre) of water		 7
  • Apply when plants are 5 to 10 cm high.
  • Repeat using a 7 to 14 day interval.
  • Do not apply more than 4 times per season.
  • Do not apply more than 3 L/ha (1.2 L/acre) per season.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements, and consult the Vegetable Production Guide: Pesticide Regulations and Safety (PDF, 421KB)
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF, 703KB)