Vegetable Production Guide

Onions, Dry Bulb
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Table 3 Dry Bulb Onion Disease Control

This section was updated - 13 January 2018

Table 3 Dry Bulb Onion Disease Control

 

Product

Rate

PHI*

Comments

Botrytis Blast or Leaf Blight

Bravo 500


(chlorothalonil)
2.4 to 4.8 L/ha
(1.0 to 1.9 L/acre)
7
  • Apply at 7 to 10 day intervals.
  • Do not apply more than 3 times per season on bulb onions.
  • Do not re-enter for 48 hours.
  • Group M fungicide.

Echo 720


(chlorothalonil)
1.7 to 3.3 L/ha
(0.7 to 1.3 L/acre)

Dithane DG
Rainshield NT


(mancozeb)

2.25 to 3.25 kg/ha
(0.9 to 1.3 kg/ acre)
10
  • DO NOT USE ON GREEN BUNCHING ONIONS.
  • Apply at 7 day intervals.
  • Add a suitable wetting agent.
  • Group M fungicide.

Dithane F-45


(mancozeb)

Group M
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)
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.
  • Add suitable wetting agent.
  • Do not enter treated area for 24 hours.
  • Group M fungicides.

Penncozeb 75DF Raincoat

(mancozeb)

Cueva

(copper octanoate)

Group M1

Use a 0.5% to 2% solution at 470 to 940 L/ha (190 to 380 L/acre) 1
  • Also controls Downy Mildew.
  • 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.
  • Do not re-enter treated area for 4 hours.

Rovral WP


(iprodione)

Group 2
1.5kg/ha
(600 g/acre)

Apply in 300 to 500 L/ha (120 to 200 L/acre) of water.
15
  • DO NOT USE ON GREEN BUNCHING ONIONS.
  • Use a non-ionic adjuvant.
  • Apply the first spray about mid-June or at first sign of leaf spotting.
  • Apply at 7 to 10 day intervals.
  • The last application in the fall may help to reduce neck rot in storage which is caused by a closely related fungus.
  • Can be tank mixed with Manzate DF to control downy mildew. See label for rates.
  • Do not enter treated area for 12 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.

Cantus WDG


(boscalid)

Group 7

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
  • Apply at 7 to 14 day intervals.
  • Do not make more than 2 sequential applications of Switch or other fungicides in the same group (9 or 12) in a season.
  • Do not apply more than 2.9 kg of product/ha/year.
  • Observe a 30 day plantback interval for crops not listed.
  • 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 500 according to Bravo 500 directions.
  • Do not enter treated area for 24 hours for hand thinning or 12 hours for all other activities.

Botrytis Leaf Blight & Suppression of Downey Mildew

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.
  • Applications to control Botrytis leaf blight will suppress downy mildew (Peronospora destructor).
  • 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.

Serenade Opti

(Bacillus subtilis)

 

smileyUsed in organics

Leaf Blight:
1.7 to 2.5 kg/ha
(700 to 1000 g/acre)

Downey Mildew:
1.7 to 3.3 kg/ha
(700 to 1300 g/acre)
0
  • Suppression only.
  • Also suppresses Botrytis Neck Rot. Use Leaf Blight rate.
  • Repeat applications using a 7 to 10 day interval.
  • smileySerenade Opti & Serenade Max (PCP# 31666, 28549) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Serenade Max

(Bacillus subtilis)
 
Note:  no longer produced. 
 
smileyUsed in organics
Leaf Blight:
3.0 to 4.5 kg/ha
(1.2 to 1.8 kg/acre)

Downey Mildew:
3.0 to 6.0 kg/ha
(1.2 to 2.4 kg/acre)

Downy Mildew

Copper oxychloride 50


(copper oxychloride)

Group M
3.0 kg/ha
(1.2 kg/acre)
1
  • Begin application in mid-June for spring seeded crops and mid-May for over wintered crops.
  • Repeat at 10 to 14 day intervals.
  • Apply in 500 L/ha (200 L/acre) of water.

Manzate DF


(mancozeb)

Group M
2.25 to 3.25 kg/ha
(0.9 to 1.3 kg/ acre)

Apply in 200 to 1000 L/ha (80 to 405 L/acre) of water
10
  • DO NOT USE ON GREEN BUNCHING ONIONS.
  • Also controls Botrytis leaf blight.
  • Do not apply to exposed bulbs.
  • Apply at 7 to 10 day intervals.
  • Can be tank mixed with Rovral WP
  • See label for rates. Use a 15 day pre-harvest interval if using this tank mix.

Zineb 80 W
(zineb)

 

Group M

0.85 to 3.3 kg/ha
(0.34 to 1.3 kg/acre)
7
  • Also controls Botrytis leaf blight (or blast).
  • Apply at 7 to 10 day intervals.
  • Apply in 1000 to 1500 L/ha (405 to 605 L/acre) of water.

Ridomil Gold MZ 68WP


(metalaxyl/mancozeb)

Group 4M
2.5 kg/ha
(1.0 kg/acre)
7
  • than 3 times per season.
  • Repeat at 7 to 14 day intervals.
  • If rotating with a contact fungicide such as Bravo or Rovral, apply within 10 days of a Ridomil Gold MZ 68WP treatment.
  • When using the 14 day interval, intersperse with Bravo, Rovral or one of the broad spectrum protectants listed below.
  • Do not enter treated area for 24 hours.

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) 10
  • Also controls Neck Rot (Botritis allii).
  • 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.
  • Do not re-enter treated areas for 48 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 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 (40L/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 in this table that is active against downy mildew. Observe most restrictive directions including rate, PHI and re-entry interval.
  • Repeat at 5 to 7day spray intervals.
  • Maximum of 5 applications per season
  • 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 for hand harvesting or thinning for 1 day.  For all other activities, do not re-enter 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.

Onion Smut

Dithane DG
Rainshield NT


(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.

Suppression of Pink Root (Phoma terrestris)

Serenade Soil

(QST 713 strain of dried Bacillus subtilis)
 
smileyUsed in organics.

 

2.7 to 14 L/ha (1.1 to 5.7 L/acre) 0
  • smileySerenade Soil (PCP# 30647) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.
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.

*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements. See also Pesticide Regulations and Safety section of this guide.
PESTICIDE GROUP DETAILS – see Pesticide Toxicity Table of this guide.

smileyOMRI-Canada = Organic Materials Review Institute of Canada

 

Viewing Section 15 of 15