Dry Bulb Onions

Dry bulb onions

Growing dry bulb onions

Expand All | Collapse All
 

Varieties

Fall-seeded (trial)

Walla Walla (sweet).

Spring-seeded

Yellow (cooking)

Frontier, Copra, Tamara, Talon, Milestone, Highlander, Mountaineer.

Yellow (Spanish)

Early (trial): Brahma, Cima, Yula, Early Shipper, Golden Cascade, Magnum, Pinnacle, Zenith.

Red

Red Beauty, Red Bull, Salsa.

See your seed dealer for the most recent variety recommendations.

 

Soil temperature

The minimum temperature for germination is 9°C. The optimum range is 16 to 24 °C.

 

Soils

 Peat or muck soils are preferred, but good crops are grown on silt loams and sandy loams.

 

Seed treatment

See Onion Smut under the Dry Bulb Onion Disease Management section of this page.

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

 

Seeding and transplanting

Over-wintered onions

Direct-seeded

Seed with a precision seeder as described for spring-seeded onions. Normal seeding date is August 15 – 20.

Seed-beds for transplant production

Usually done the first week of August. Sow 2.75 kg seed for each hectare (1.1 kg/acre) to be set, approximately 35 kg/ha (14 kg/acre) of seed-bed. One hectare of seed-bed will produce enough transplants for 12 hectares of onions. Seed is drilled to a depth of 2.5 cm or slightly less.

Seed may be drilled with a wide shoe attachment which scatters the seed over a 10 cm band in rows with 40 cm centres. The second method is to use a tractor-drawn gang drill which drops the seed thickly in rows 5 to 7.5 cm apart. This results in solid beds with widths depending on tractor wheel settings.

The third method is to drill the seed thickly in single rows 20 to 22 cm apart. In the spring the plants in every other row are lifted and used for transplants. The remaining rows are thinned by hand, leaving a plant every 7.5 cm for a crop. In the Southern Interior, light sprinkler irrigation following the seeding will often be necessary to obtain a satisfactory stand.

In the spring, loosen plants before pulling and tie in bundles of 100 to 200. If being moved any distance, or if transplanting will be delayed, store at 0 to 2°C with relative humidity of 90%. Immediately before planting, trim the plants to leave 1.5 cm of the original root and 10 cm of the green top. Set in rows 40 cm apart, with 6 to 7.5 cm between plants.

Spring-seeded onions

Onions may be seeded as soon as the land can be made ready, but mid-April is considered ideal. Seeding should be completed by May 1. Approximately 3.25 kg raw seed per ha (1.3 kg/acre) is required. For precision seeding see next paragraph. When using the Planet Junior drill with 10 cm scatter shoe, the drills should be set to drop 11 seeds per 25 cm of row 2 to 2.5 cm deep. Row spacing is usually 4 rows per bed on 1.8 m centres.

Precision seeding

This method of placing individual seeds at a predetermined spacing within a row produces a crop of more uniform size, less culls and higher yield. Use coated seed and sow two lines 7.5 cm apart per row with 12 seeds per 25 cm of row. Row spacing is usually 4 rows on 1.8 m beds.

With normal coating and spacing approximately 18 kg/ha (7 kg/acre) of seed will be required. This results in a population of approximately 925,000 plants/ha (370,000 plants/acre). See “Precision Seeding” section of the Vegetable Production Guide: Planting (PDF).

 

Irrigation

Onions are shallow-rooted, and unless their moisture supply is constant, they will “bulb out” early and the resulting sizes may be small. Four or five irrigations per season are usually required. Irrigation should be discontinued after the first week in August to encourage crop maturity and limit disease development.

 

Fertilizer

A soil test is necessary to determine phosphate and potash requirements. Use the Vegetable Production Guide: Nutrient Management (PDF) for recommendations based on soil test results.

Coastal area (muck soil)

Where no manure has been applied, broadcast and disc in 70 kg/ha (28 kg/acre) nitrogen and all of the required potash and phosphate.

Interior of B.C.

Where no manure has been applied, broadcast and disc in 90 kg/ha (36 kg/acre) nitrogen and all the required phosphate and potash.

 

Onion growth stages

Diagram of onion growth stages

 

Harvesting, curing and storage

Dig when two-thirds of the tops are down, and cure by windrowing in the field if weather conditions are favourable. Running them up and over a potato digger a few days after digging will shorten the drying period. This should be done after each rainfall. Under wet conditions or after field drying has occurred, the onions should be placed in storage sheds. Under wet conditions the height of the onion pile should not exceed 3 m.

Curing is completed or accomplished by forcing air of a lower relative humidity than the air inside the storage through the bottom of the onion pile to the top; one and one-half cubic metres of air per minute for each cubic metre of onions is recommended. If the weather is cool and wet, forced air at 24 to 30°C and 70% relative humidity is recommended.

If the onions are also wet, forced air at 30°C and a relative humidity of less than 70%, should be used as soon as loading is completed. This should be continued until the outer skins and neck are dry. Then the crop should be allowed to cool gradually by slowly reducing the temperature to that of the outside air (0°C and above). After curing, the relative humidity in the storage should be maintained between 60 and 70%.

The less fluctuation the better. During dry, cold weather (above 0°C) the vents may be opened and the fans used to circulate cold outside air throughout the pile. During wet or very cold weather (below 0°C) the building should remain closed and the air within should be re-circulated periodically.

 

Dry bulb onion weed management

Expand All | Collapse All
 

Stale seedbed

Stale seedbed: herbicide application rates
Product Rate PHI* Comments

Ignite 15 SN

(glufosinate ammonium)

Group 10		 2.7 to 5.0 L/ha
(1.1 to 2.0 L/acre)

Apply in 110 to 330 L/ha (45 to 135 L/acre) of water at 275 to 310 kPa 		N/A
  • May be used for annual grasses and broad leaf weeds.
  • Do not handle with bare hands or with leather or cloth gloves.
  • Rainfall within 4 hours may reduce effectiveness.
  • See section on stale seed bed technique as described in the Vegetable Production Guide: Pest Management (PDF, 1.2 MB).

*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).

 

Pre-emergence

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

Dacthal W-75

(chlorthal)

Group 3

Note:  no longer produced.  Registration expires December 31, 2023

 9.0 to 18.0 kg/ha
(3.6 – 7.2 kg/acre)		 N/A
  • Controls lamb’s-quarters, crabgrass, purslane, foxtail and chickweed.
  • Do not use on soils with more than 5% organic matter.
  • Rate varies with soil texture and organic matter.

Chateau

(flumioxazin)

Group 14		 140 g/ha
(57 g/acre)

Transplanted onions:
2- to 6- leaf stage

Direct seed onions:
3- to 6- leaf stage		 45
  • Suppresses redroot pigweed, lamb’s-quarters, hairy nightshade and black nightshade.
  • Apply prior to emergence of weeds.
  • Apply only once during the growing season.
  • Use only on muck soils and medium textured mineral soils with <5% OM.
  • Control may be improved by irrigation with at least ½ cm of water.
  • Applications made to poorly drained soils or under cool, wet conditions may result in crop injury.
  • 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).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF).

 

Post-emergence

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

Frontier Max

(dimethenamid -P)

Group 15

1.29 L/ha
(520 mL/acre)

Apply using 200 to 300 kPa spray pressure.

 60
  • Suppresses yellow nutsedge on muck soils only.
  • Apply at the loop stage only and before yellow nutsedge emerges.
  • Apply no more than once per season.
  • On muck soils, observe a plantback interval of 11 months for carrots, transplanted celery and onions.  See label precaution for other crops on muck soils.

Goal 2XL

(oxyfluorfen)

Group 14		 Onions (2 true leaves):
Weeds (2 – 4 leaf stage):
500 mL/ha
(200 mL/acre)

Apply in 500 L/ha (200 L/acre) of water at 275 kPa 		56
  • Controls broadleaf weeds including purslane, redroot pigweed, lamb’s-quarters and wild buckwheat.
  • Apply when weeds are in 2 to 4 leaf stage.
  • Can cause necrotic lesions and twisting or pigtailing of onions which will be more severe if applied during periods of stress or following periods of rainy, cool weather.
  • Do not apply to sandy soil.
  • Additional applications may be necessary to control late germinating weeds.
  • Do not apply more than 2.0 L/ha (0.8 L/acre) in one year.
  • Do not add oil or surfactants to the spray mixture.
  • Do not enter treated area for 48 hours.

Prowl H2O

(pendimethalin)

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

Mineral soils:
2.42 L/ha
(1 L/acre)
 
Apply in 250 L/ha (100 L/acre) of water at 138 to 276 kPa.
 N/A

Muck soils: 

  • Apply, using the muck soil rate, at the loop and 2 true leaf stage of onion development, before emergence of weeds on muck soils.
  • Treatment at both stages is required for season-long weed control on muck soils. Controls barnyard grass, crab grass, green and yellow foxtail, chickweed, lamb’s-quarters and pigweed.
  • In the event of a crop failure after application, only onions may be reseeded the same year.
  • Carrots and direct-seeded lettuce may be planted into soil treated the previous year.

Mineral soils:

  • Make one application, using the indicated mineral soil rate, between the loop and 2 true leaf stage.
  • Controls only green foxtail, redroot pigweed and lamb’s-quarters.

All soils:

  • Do not use on onions grown from sets. 
  • Rain or irrigation within 7 days of application improves control.
  • Do not tank mix with Chateau.
  • Do not enter treated area for 24 hours.

Centurion/Select

(clethodim)

Group 1

 0.19 to 0.38 L/ha
(77 to 154 mL/acre

Apply in 55 to 225 L/ha (22 to 90 L/acre) of water at 275 kPa 		45
  • Also registered on dry bulb shallots.
  • Do not apply more than 1 time per season.
  • Do not apply more than 0.38 L/ha (154 mL/acre) per season.
  • Apply when crop is in the 1 to 4 leaf stage.
  • Centurion/Select is to be used only with the adjuvant Amigo at 0.5 to 1.0% v/v.
  • Arrow 240 EC is to be used only with the adjuvant X-Act at 0.5 to 1.0 % v/v.
  • See label for rates depending on weed types and weed-leaf growth stages.
  • Controls annual grasses and suppresses quack grass.
  • Allow 4 days between this application and any other chemical not found on the label.
  • Do not 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)		 50
  • 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 when annual weeds are in the 1 to 6 leaf stage and when quackgrass is in the 1 to 3 leaf stage.
  • 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.
  • Observe a 30 day plantback interval for crops not listed.
  • Do not enter treated area for 12 hours.

Excel Super

(fenoxaprop-pethyl)

Group 1		 670 mL/ha
(270 mL/acre)

Apply in at least 110 L/ha (45 L/acre) water at 275 kPa 		38
  • Apply at the 1 to 6 leaf stage of seedling grasses.
  • Controls foxtail, barnyard grass, crabgrass, fall panicum, Proso millet and old witch grass.
  • Do not apply any other pesticides, or chemicals 4 days before or after the application.
  • Does not control quackgrasses, sedges or perennial grasses.

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)

42
 

 

42
 

 

42
 

 

60
  • 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.
  • 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.
  • Apply using 425 kPa pressure for dense weed infestations or dense crop canopies.
  • 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.

Pardner

(bromoxynil)

Group 6		 500 mL/ha
(200 mL/acre)		 75
  • Make two applications per season at an interval of 10 to 18 days.
  • Make 1st application when onion are at the 2- to 3-leaf stage.
  • Apply a 2nd time when onions are at the 4- to 5- leaf stage.
  • Controls common groundsel to the four leaf stage.
  • Bromotril will also control red root pigweed.
  • Apply in 200L/ha (80 L/acre) of water at 170 kPa.
  • Pardner may cause severe leaf burn in onions if the waxy layer on the leaf has not developed.

Bromotril 240 EC

(bromoxynil)

Group 6		 600 mL/ha
(250 mL/acre)		 75
  • Make two applications per season at an interval of 10 to 18 days.
  • Make 1st application when onion are at the 2- to 3-leaf stage.
  • Apply a 2nd time when onions are at the 4- to 5- leaf stage.
  • Controls common groundsel to the four leaf stage.
  • Bromotril will also control red root pigweed.
  • Apply in 200L/ha (80 L/acre) of water at 170 kPa.
  • Pardner may cause severe leaf burn in onions if the waxy layer on the leaf has not developed.

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.

*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).

 

Dry bulb onion insect management

Expand All | Collapse All
 

Leafminer

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

 

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

Cull piles should be removed to the dump or buried to prevent onion fly breeding and subsequent field infestation.

Dry bulb onions (including silverskins) grown from seed

A combination of furrow and foliage or foliage treatments alone are required.

Furrow treatment for maggot control

Note:  Lorsban 15G is no longer produced.   Do not use on crops for export to the USA.

Growers equipped with multiple-row seeders or transplanters and granular chemical applicators should place granular insecticide in the furrow with the seed or transplant at transplanting time. For best results the granular insecticide must be in direct contact with the seed. (If seeding before March 15, the granular treatment is not necessary.)

Use Lorsban 15G at 32 grams/100 m of row (6.9 kg/ha for 4-row beds at 180 cm centres or 2.8 kg/acre for 4-row beds at 180 cm centres.) Do not apply within 109 days of harvest for dry bulb onions, or 97 days for pickling onions. Do not enter treated area for 1 day.

Do not use Lorsban 15G on green bunching onions or on onions grown from sets.

Note: If your fields are being monitored for onion flies, follow spray recommendations of the person who does the monitoring. If fields are not being monitored, apply foliage sprays four weeks after seeding or earlier if damage is observed. See under B. Do not apply sprays before April 15.

Foliage treatments

If the furrow treatments are not used, apply sprays at 7 to 10 day intervals beginning after seedling emergence, but no earlier than April 15. For crops planted in late April or May, the first spray should be applied 4 days after seeding. Spraying should begin four weeks after planting with a furrow treatment. In all cases, spraying should continue until July 15.

Note: If your fields are being monitored for onion flies, follow spray recommendations of the person who does the monitoring.

Spraying of weeds immediately surrounding onion fields will give additional protection against the onion maggot. Caution: Do not spray headland areas where water may become contaminated. 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. Try to achieve a very narrow band over the row. If maggots become bigger than 2 or 3 instars, a spray will not be effective but should control future emergence. To deter insects from developing resistance, alternate sprays between the two groups listed in the table below.

Sets, multipliers, and transplants

Use the furrow and foliage treatments or the foliage treatments alone, as given above and in the table below.

Note: The chemicals applied, as recommended, will aid in the control of thrips.

Onion maggot foliar sprays
Product Rate PHI* Comments

Dibrom

(naled)

Group 1B
 550 mL/ha
(220 mL/acre)

Apply in 100 to 300 L/ha (40 to 120 L/acre) of water		 4
  • Applications during hot weather may result in crop injury.
  • Do not apply in temperatures over 32°C.
  • Do not apply more than twice per season.
  • Do not enter treated area for 48 hours.

Mako

(cypermethrin)
 
Group 3

175 mL/ha
(70 mL/acre)

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

3
  • Repeat using 7 day intervals.
  • Maximum of 3 applications per season.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • 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
  • Maximum of 3 applications per season.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • 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).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF).

 

Thrips

Very tiny (1 mm), thin, black, brown or yellowish, active insects causing silvering of the leaves. Black fecal spots can be seen where thrips are feeding. When severe, entire plant may wilt and die. Damage may resemble Botrytis (see below).

Control

When thrips are present, using sufficient water to provide good coverage, spray three times at 10 day intervals beginning the third week of June with:

Dibrom at the rates and days to harvest restrictions given under Foliage Treatments for Maggot Control. See table below for other products.

Chemical control of thrips
Product Rate PHI* Comments

Dibrom

(naled)

Group 1B		 550 mL/ha
(220 mL/acre)

Apply in 100 to 300 L/ha (40 to 120 L/acre) of water.		 4
  • Applications during hot weather may result in crop injury.
  • Do not apply in temperatures over 32°C.
  • Do not apply more than twice per season.
  • Do not enter treated area for 48 hours.

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 7 day intervals.
  • Maximum of 3 applications per season.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • 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.
  • 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.

Malathion 85E

(malathion)

Group 1B
1.1 L/ha
(0.44 L/acre)
 
Apply in 1000 L/ha (405 L/acre) of water
3
  • Do not apply more than one time per year.
  • Best control is obtained when temperature is above 20° C.
  • Toxic to fish.
  • Do not apply where runoff is likely to occur.
  • Do not apply after expiry date on the container label.
  • Do not re-enter treated area for 12 hours.

Matador 120EC

(lambda- cyhalothrin)
 
Group 3
 188 mL (76 mL)

Apply in 500 L/ha (200 L/acre) of water 		14
  • Allow a 7 day interval between applications.
  • Do not apply more than 3 times per season.
  • Do not enter treated areas for 24 hours.

Silencer 120EC

(lambda-cyhalothrin)

 Group 3

 188 mL (76 mL)

Apply in 500 L/ha (200 L/acre) of water 		14
  • Allow a 7 day interval between applications.
  • Do not apply more than 3 times per season.
  • Do not enter treated areas for 24 hours.

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

(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 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.

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.

Movento 240 SC

(spirotetramat)

Group 23

365 mL/ha
(150 mL/acre)

Apply in 200 L/ha (80 L/acre) of water		 3
  • 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 during crop flowering period or when flowering weeds are present.

Agri-Mek 1.9% EC

(abamectin)

Group 6 

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

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

 30
  • Apply when onion thrips first appear.
  • Use a non-ionic surfactant at the rate of 0.25 to 0.5% v/v of spray mixture.
  • Repeat at 7 day intervals.
  • Do not apply more than three times per season.
  • Highly toxic to bees exposed to direct treatment, drift or residues from blooming plants.
  • Check label for re-entry.

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

 30
  • Apply when onion thrips first appear.
  • Use a non-ionic surfactant at the rate of 0.25 to 0.5% v/v of spray mixture.
  • Repeat at 7 day intervals.
  • Do not apply more than three times per season.
  • Highly toxic to bees exposed to direct treatment, drift or residues from blooming plants.
  • Check label for re-entry.

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).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF).

OMRI-USA = Organic Materials Review Institute of USA

 

Dry bulb onion disease management

Expand All | Collapse All
 

Botrytis blast or leaf blight

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

Control

  • Avoid high rates of seeding as dense crops are most severely affected.
  • Avoid high rates of nitrogen fertilizer.
  • Avoid sprinkler irrigation if blast is apparent.
  • See table below for registered products.

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

Bravo ZN

(chlorothalonil)
 
Group M5
 2.4 to 4.8 L/ha
(1.0 to 1.9 L/acre)		 7
  • 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.
  • For PPE requirements while mixing and handling Bravo products, check the labels.  
  • 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)		 7
  • 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.

Dithane
Rainshield

(mancozeb)
 
Group M3
 2.25 kg/ha
(0.9 kg/ acre)		 14
  • Do not use on green bunching onions.
  • Apply as a foliar spray at 7 day intervals.
  • Do not make more than 6 applications per year.
  • Add a suitable wetting agent.
  • Check label for PPE requirements when mixing and loading and during open-cab ground boom application.
  • Do not re-enter treated area for 1 day for hand weeding, and for 12 hours for all other activities.

Dithane F-45

(mancozeb)

Group M
 
Note:  no longer produced.  Registration expires November 2023
 
 3.8 to 5.5 L/ha
(1.5 to 2.2 L/acre)		 10
  • Apply when the disease first appears.
  • Repeat every 7 days.
  • Do not use on green bunching onions.

Penncozeb 75DF

(mancozeb)
 
Group M
 2.25 to 3.25 kg/ha
(0.9 to 1.3 kg/acre)		 10
  • Do not use on green bunching onions.
  • Repeat at 7 day intervals.
  • Do not enter treated area for 24 hours.

Penncozeb 75DF Raincoat

(mancozeb)
 
Group M
 2.25 kg/ha
(0.9 /acre)		 14
  • Do not use on green bunching onions.
  • Do not apply to exposed bulbs.
  • Repeat at 7 day intervals.
  • Do not make more than 6 applications/ha per year.
  • Do no apply more than 13.5 kg/ha (5.5 kg/ac) per year).
  • Check label for PPE requirements when mixing and loading and during open-cab ground boom application.
  • For hand weeding, do not enter treated area for 24 hours.
  • For all other activities do not re-enter for 12 hours.

Zineb 80 W

(zineb)

 

Group M

0.85 to 3.3 kg/ha
(0.34 to 1.3 kg/acre)

Apply in 1000 to 1500 L/ha (405 to 605 L/acre) of water

 7
  • Apply using a 7 to 10 day interval.

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.

Lance WDG

(boscalid)

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

Apply in 100 L/ha (40 L/acre) of water 		7
  • Will also control of purple blotch.
  • 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.
  • For crops not on the label, observe a plant back interval of 14 days.
  • Do not enter treated area for 12 hours.

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.

Miravis Duo

(pydiflumetofen & difenoconazole)

Group 7 & 3

1.0 L/ha (405 mL/ac)

 

Apply in 150 L/ha (60 L/ac) of water		 7
  • Suppression only of botrytis leaf blight.
  • Also registered on shallots (bulb).
  • Repeat using a 7 to 14 day interval.
  • Do not make more than 2 consecutive applications before switching to a non-Group 7 & 3 fungicide.
  • Do not apply more than 4.0 L/ha (1.6 L/ac) per season.
  • See label for details on plantback interval.
  • Do not re-enter treated area for 12 hours.

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.
  • Observe a 30 day plantback interval for crops not listed.
  • Do not enter treated area for hand weeding for 3 days, and for all other activities do not re-enter for 12 hours.

Scala SC

(pyrimethanil)

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

Apply in 300 L/ha (120 L/acre) of water 		7
  • Controls leaf blight.
  • Tank mix with Bravo ZN.  See this table for Bravo ZN directions.  Follow the most stringent label precautions for mixing loading and applying stated on both labels.
  • Apply using a 7 to 14 day interval.
  • Maximum application of 6 L/ha (2.4 L/acre) per season.
  • 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.
  • 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
 1000 to 1300 g/ ha
(405 to 525 g/acre)		 7
  • Begin applications prior to disease development and continue on a 7 to 14 day schedule.
  • Do not apply more than 6 times per season.
  • Do not make sequential applications when downy mildew occurs, 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 until residues have dried.

Allegro 500 F

(fluazinam)

Group 29
 1.16 L/ha
(470 mL/acre)

Apply in 100 L/ha (40 L/acre)		 7
  • Suppression only.
  • Also suppresses purple blotch.  Check label.
  • Apply as a foliar broadcast spray.
  • Repeat using a 7 to 10 day application interval.
  • Do not make more than 5 applications.
  • See label for plantback interval details.
  • Do not enter treated area for 3 days for hand weeding, and for all other activities for 24 hours.

Serenade Opti

(Bacillus subtilis)
Used in organics
 Leaf Blight:
1.7 to 2.5 kg/ha
(700 to 1000 g/acre)		 0
  • Suppression only.
  • Repeat applications using a 7 to 10 day interval.
  • Serenade Opti (PCP# 31666) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

*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).

OMRI-Canada = Organic Materials Review Institute of Canada

 

Botrytis neck rot

Rot usually begins in the neck. Rotted tissues become water-soaked and soft. A grey mould develops on the surface, later containing hard, black sclerotia. It affects bulbs during curing and storage.

Control

  • Grow early-maturing tight-necked varieties.
  • Do not irrigate after the first week in August.
  • Dig bulbs when two-thirds of the tops are down.
  • Dry thoroughly for 8 to 18 days. Artificial drying may be necessary in wetter than normal season.
  • Store in well-ventilated storage at 0 to 4°C, with low humidity of 70%.

Chemical control of botrytis neck rot
Product Rate PHI* Comments

Serenade Opti

(Bacillus subtilis)
Used in organics
 (700 to 1000 g/acre) 0
  • Suppression only.
  • Repeat applications using a 7 to 10 day interval.
  • Serenade Opti (PCP# 31666) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Acapela

(picoxystrobin)

Group 11

0.44 to 0.88 L/ha
(180 to 400 mL/acre)

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

 0
  • 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.

Scala SC

(pyrimethanil)

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

Apply in 300 L/ha (120 L/acre) of water		 7
  • Apply using a 7 to 14 day interval.
  • Maximum application of 6 L/ha (2.4 L/acre) per season.
  • Do not enter treated area for 24 hours for hand thinning or 12 hours for all other activities.

Gavel DF

(mancozeb/zoxamide)

Group M3 & 22 

1.7 to 2.25 kg

(690 to 900 g/acre)

 14
  • Repeat using a 7 day interval.
  • Do not make more than 8 applications per season.
  • Do not apply more than 18 kg/ha (7.3 kg/acre) per season.
  • Do not apply to exposed bulb.
  • Do not allow spray or drift to contact bulbs after lifting from the soil.
  • Observe a plantback interval of 30 days for leafy vegetables and root and tuber vegetables.  For all other crops not listed, observe a plantback interval of 140 days.
  • Check label for PPE requirements when mixing and loading and during open-cab ground boom application.
  • For hand weeding, do not re-enter treated areas for 1 day.
  • For all other activities do not re-enter 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).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF). 

 

Downy mildew

(Pernospora)

This fungus, which overwinters in bulbs, 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

  • Practice sanitation and rotation. Cull piles with onions growing on them are an important source of inoculum.
  • Avoid planting spring-seeded onions near overwintering onions or near onions grown from sets.
  • Keep cultivations to a minimum and cultivate preferably when the leaves are dry.
  • Spray every 7 to 14 days commencing June 1 for transplanted crops, and June 15 for spring-seeded crops, or when you are advised by your field scout. Add a spreader to obtain good coverage. Use 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.
  • Repeat applications using a 7 to 10 day interval.
  • Serenade Opti (PCP# 31666) 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 M

3.0 kg/ha
(1.2 kg/acre)

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

 1
  • Begin application in mid-June for spring seeded crops and mid-May for over wintered crops.
  • Repeat at 10 to 14 day intervals.

Zineb 80 W

(zineb)
 
Group M

0.85 to 3.3 kg/ha
(0.34 to 1.3 kg/acre)

Apply in 1000 to 1500 L/ha (405 to 605 L/acre) of water

 7
  • Apply using a 7 to 10 day interval.

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. 

Pristine WG

(boscalid & pyraclostrobin)

Group 7 & 11
 1000 to 1300 g/ ha
(405 to 525 g/acre)		 7
  • Suppression only.
  • Begin applications prior to disease development and continue on a 7 to 14 day schedule.
  • Do not apply more than 6 times per season.
  • Do not make sequential applications when downy mildew occurs, 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 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 enter treated area until residues have dried.

Cabrio EG

(pyraclostrobin)

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

Apply in 225 L/ha (90 L/acre) of water		 7
  • Repeat using a 10 day intervals.
  • No more than 3 applications per season.
  • Do not use treated crops for feed.
  • Do not re-enter for thinning for 3 days and for all other activities, do not re-enter 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 using a 7 to 14 day interval.
  • Do not apply more than 4 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. 

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.

Gavel DF

(mancozeb/zoxamide)
 
Group M3 & 22 
 1.7 to 2.25 kg                   (690 to 900 g/acre) 14
  • Repeat using a 7 day interval.
  • Do not make more than 8 applications per season.
  • Do not apply more than 18 kg/ha (7.3 kg/acre) per season.
  • Do not apply to exposed bulb.
  • Do not allow spray or drift to contact bulbs after lifting from the soil.
  • Observe a plantback interval of 30 days for leafy vegetables and root and tuber vegetables.  For all other crops not listed, observe a plantback interval of 140 days.
  • Check label for PPE requirements when mixing and loading and during open-cab ground boom application.
  • For hand weeding, do not re-enter treated areas for 1 day.
  • For all other activities do not re-enter 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
  • Apply when conditions favour disease development.
  • 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 area 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.

Revus

(mandipropamid)

Group 40
 400 to 600 mL/ha
(160 to 240 mL/acre)

Apply in 100 L/ha (40 L/acre) of water 		7
  • Use a non-ionic adjuvant (0.125% v/v).
  • Repeat at 7 day intervals.
  • Do not apply more than 4 times per year.
  • May be tank-mixed with Bravo 500. Check Bravo Label for PHI and re-entry intervals.
  • Do not 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

(oxathiapiprolin)
 
Group 49

88 to 350 mL/ha (35 to 140 mL/acre

Apply in 110 L/ha (45 L/acre) of water.

 0
  • Repeat at 5 to 10 day intervals.
  • Where multiple crop cycles are produced in the same year, do not make more than 6 applications/ha/year.
  • Do not apply more than 1.40 L/ha (570 mL/acre) 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).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF).

OMRI-Canada = Organic Materials Review Institute of Canada

 

Fusarium basal rot

Plants appear stunted and lopsided. Bulbs have soft, mealy decay at base or on one side. Rot continues in storage.

Control

  • Control onion-maggot.
  • Follow four-year crop rotation with non-susceptible crops such as carrots, celery, lettuce and beets.
  • Avoid root and bulb injury during cultivation.
  • During storage and transit, keep temperature below 4°C.
  • Use only disease-free sets. This is especially important on new land or after rotation, so as to avoid contamination.
 

Onion smut

Powdery brown to black, elongated blisters develop within the cotyledons, leaves and scales of seedling plants; most affected seedlings die while young; some persist and lesions may occur on mature bulbs.

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.

Chemical control of onion smut
Product Rate PHI* Comments

Dithane
Rainshield

(mancozeb)

Group M3
 4.4 to 8.8 kg/ha
(1.8 to 3.5 kg/acre)		 100
  • Do not use on green bunching onions.
  • Apply as a granular in the furrow at seeding time.
  • Do not apply more than 1 time per year.
  • Check label for PPE requirements when mixing and loading and during open-cab ground boom application.
  • 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).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF).

 

Pink root

(Phoma)

This is a soil-borne fungal disease. Infected roots become pink and die. Plants appear to be nutrient deficient. The disease can appear at any time of plant development, from seedling stage to maturity.

Control

No satisfactory control measure is known, but the following are good general recommendations:

  • Rotate with lettuce, celery, beets, potatoes, rutabagas or other crops unrelated to onions. The fungus will survive on cereals grown in rotation.
  • Do not plant onions in severely infested land.
  • Ensure rapid bulb growth by the use of adequate fertilizer, irrigation, cultivation, cover crops, etc.
  • Do not plant infected plants.
  • Soil fumigation is effective on sandy but not on muck soils.

Chemical suppression of pink root (Phoma terrestris)
Product Rate PHI* Comments

Serenade Soil

(QST 713 strain of dried Bacillus subtilis)
 
Used in organics

 

 2.7 to 14 L/ha (1.1 to 5.7 L/acre) 0
Surface Application:
  • Apply as a 15 cm band over the top of the seed row as a broadcast spray after planting.
  • Ensure incorporation into the seed zone within 24 hours of application via rainfall or overhead irrigation.
Post-plant applications:
  • After crop germination, additional applications may be made to the soil as a drench or spray directed towards the base of the plant.
  • Irrigate to move material into the seed or root zone.
  • Repeat at 21 to 28 day intervals.
  • Serenade Soil (PCP# 30647) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

*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).

OMRI-Canada = Organic Materials Review Institute of Canada

 

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.

 

Sprout inhibition

Sprout inhibition will extend the storage period and, therefore the selling period for storage onions. Use Royal MH 30 XTRA (maleic hydrazide) at 8.36 L/ha (3.4 L/acre) in a minimum of 300 L/ha (120 L/acre) water by ground equipment. Necessary conditions for best results are:

  • A uniform or even-growth crop.
  • 50% of the tops down, and all tops with at least 5 to 8 green leaves. This condition usually occurs about 10 days to two weeks before harvest time.
  • No rain or irrigation for 24 hours after application.
  • Plants should be healthy and reasonably free of insect or disease damage.
  • Use on storage varieties. Royal MH 30 XTRA will not make a poor-keeping variety into a storage variety.
  • Do not spray too early as spongy hollow-necked bulbs may result.
  • Spray during early morning or on cloudy days.
  • Apply at temperatures below 25 °C.
  • Observe a 10 day pre-harvest interval.
 

Suppression of Stemphylium leaf blight

Chemical suppression of Stemphylium 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.

Miravis Duo

(pydiflumetofen & difenoconazole)

 

Group 7 & 3

1.0 L/ha (405 mL/ac)

 

Apply in 150 L/ha (60 L/ac) of water		 7
  • Repeat using a 7 to 14 day interval.
  • Do not make more than 2 consecutive applications before switching to a non-Group 7 & 3 fungicide.
  • Do not apply more than 4.0 L/ha (1.6 L/ac) per season.
  • See label for details on plantback interval.
  • 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).
PESTICIDE GROUP DETAILS – see the Vegetable Production Guide: Pesticide Toxicity Table (PDF).