Lettuce

Lettuce

Growing lettuce

Expand All | Collapse All
 

Varieties

Iceberg (Crisphead)

Early

El Dorado.

Main season

Summertime (bolting resistant; downy mildew susceptible; requires early fertilization and irrigation to attain size).

Late

Patriot, El Dorado.

Butterhead

Optima.

Leaf green

Two Star, Shining Star, Bergman’s Green.

Red

New Red Fire, Red Fox.

Romaine (Cos)

Parris Island 454, Darkland Cos, Paramount.

See your seed dealer for the most recent variety recommendations.

 

Seeds and seed treatment

Seed

Approximately 275 g of seed will supply sufficient seedlings to transplant 1 hectare (110 g of seed/acre). For direct field seeding 1.0 to 2.25 kg/ha of raw seed (0.4 to 0.9 kg/acre) is required. For precision seeding, 3 to 4 kg/ha (1.4 to 1.8 kg/acre) of coated seed should be sufficient.

Seed treatment

Use seed treated with Thiram seed protectants.

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

 

Soil

The sandy peat mucks, deep black sandy loams and loams are the most suitable types of soil. Good moisture-holding capacity with good drainage is important.

Soil temperature

Germination occurs at as low as 4°C and may not occur at temperatures of 21°C and over unless irrigation is used to cool the soil. Crop growth is usually good between 16 and 18°C.

 

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.

Broadcast and disc in all the required phosphate and potash, and the following amounts of nitrogen (N):

Western Iceberg types (Salinas, Target, Alpha)

Muck soils

Early season

50 to 80 kg /ha N (20 to 32 kg/acre)

Main season

40 to 60 kg /ha N (16 to 24 kg/acre)

These rates are total N requirements. If application is split, the total of the preplant broadcast and the side-dress application should be within the above ranges. Use lower rates on deep mucks, higher rates on shallow muck soils.

Mineral soils

Early season

100 to 125 kg/ha N (40 to 50 kg/acre)

Main season

75 to 100 kg/ha N (30 to 40 kg/acre)

If necessary, an additional 30 to 50 kg/ha N (12 to 20 kg/acre) may be side-dressed on early plantings.

Leaf types (Romaine and green leaf) and Eastern Iceberg types (e.g. Ithaca and Summertime)

Early and main season

100 to 150 kg/ha N (40 to 60 kg/acre). Use the higher rate for mineral soils, lower rate for muck soils. Side-dress up to an additional 50 kg/ha N (20 kg/acre) on early plantings.

 

Seeding and transplanting

The earliest seedings are started in flats in greenhouses in early February. The seedlings are pricked out into other flats (about 70 per flat) and are planted out as soon as the fields can be prepared. Some producers are now using plug transplants to achieve greater product uniformity and to reduce thinning labour and weed problems. Raised beds with tractor wheels on 1.8 m centres are marked out to achieve four rows 36 cm apart with 28 to 32 cm between plants. Early transplants benefit from a soaking with a starter solution, high in phosphate, just prior to transplanting.

Precision seeding

A single coated seed placed every 5 – 7.5 cm or 3 seeds in-line 2.5 cm apart at 30 cm centres is the usual practice. The plants are thinned at the two or three leaf stage leaving a final spacing of 4 rows 36 cm apart on a raised bed with tractor wheels at 1.8 meters and with plants 28 to 32 cm apart within the row. These spacings result in a final population of approximately 77,500 plants/ha (31,000 plants/acre).

 

Lettuce weed management

Lettuce is sensitive to most herbicides, hence there are few treatments that can be recommended. Cultural weed controls are beneficial. Crop rotations, clean-up of perennial weeds in another crop before planting lettuce, using only well rotted weed-free manure, clean-up of annual weeds before planting and tilling between rows are practices that will reduce hand weeding.

Use of Ignite or Roundup as a stale seed-bed application will help control the first flush of weeds. Check the Pest Management section of the Vegetable Production Guide: Pest Management (PDF, 1.2 MB) for more information.

There is only one post-emergence recommendation, so “in season” cultivation should begin as soon as weeds emerge (see tables below).

Expand All | Collapse All
 

Pre-emergence

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

Kerb 50 WSP


(propyzamide)

Group 15		 2.2 kg/ha
(900 g/acre)

Apply in 300 to 500 L/ha (120 to 200 L/acre) of water 		Direct seeded:
55
  • Direct seeded – apply pre-plant incorporated, pre-emergence or post-emergence.
  • Transplanted – apply 7 to 10 days after transplanting.
  • Do not make more than 1 application per year.
  • Is not effective on high organic matter soils.
  • Do not replant lettuce in treated fields in the same year. See label for more plant back restrictions.
  • Does not control dandelion or Canadian thistle.

*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
  • Do not use in greenhouses.
  • Annual bluegrass and broadleaved weeds are not controlled.
  • Apply as a broadcast spray.
  • Do not apply more than once 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.

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 actively growing 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.

Poast Ultra

(sethoxydim)

Group 1

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
  • For transplanted lettuce:  apply 1 time per year.
  • For direct-seeded lettuce:  2 applications per year can be made to a total maximum application rate of 1.1 L/ha (445 mL/ac).
  • 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.
  • For direct-seeded lettuce, make 2nd application 14 to 21 days after thinning.
  •  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.

*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).

 

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.
  • Consult the section on stale seed bed technique in the Vegetable Production Guide: Pest Management (PDF, 1.2 MB) for more information.

*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).

 

Lettuce insect management

Expand All | Collapse All
 

Aphids (foliar)

Lettuce aphids are small, green or pinkish, sucking insects that feed on the inner leaves and within the lettuce heads. Other aphids feed on the undersides of leaves and curl or stunt them.

Monitoring (scouting)

The need for applying sprays can be determined by checking fields weekly to see if aphids are present. To do this, walk down the outside beds and up the centre bed of each planting, examining 4 plants at equal intervals within each bed.

Strip off all the leaves, including head leaves and inspect every one for aphids. If one or more aphids are found in the field, a control program should be undertaken throughout the growing season with products listed in the table below.

Chemical control of aphids
Product Rate PHI* Comments

Cygon 480/ Lagon 480 E

(dimethoate)

Group 1B

700 mL/ha
(280 mL/acre)

 14
  • Do not use on head lettuce.
  • Apply as a groundspray using a closed cab.
  • Use sufficient water for good coverage.
  • Repeat using a 7 day interval.
  • Do not apply more than 2 times per season.
  • Toxic to bees.  Do not apply when bees are foraging in the treatment area.
  • Do not re-enter treated area for 3 days.

Dibrom

(naled)

Group 1B

1.1 to 1.65 L/ha
(440 to 665 mL/acre)

Apply in 100 to 300 L/ha (40 to 120 L/acre) of water

 4
  • Application during hot weather may result in crop injury
  • Do not apply in temperature over 32°C.
  • Do not enter treated area for 48 hours.

Orthene 75 SP

(acephate)

Group 1B		 563 to 825 g/ha
(228 to 335 g/acre)		 7
  • Use on head lettuce only.
  • Do not feed trimmings to livestock.
  • Do not apply more than 4 times per season.
  • Do not enter treated area for 1 day. For activities involving significant foliar contact, gloves and cotton coveralls must be worn for 2 weeks.

Admire 240 F/ Alias 240 C

(imidacloprid)

Group 4
 Pre-transplant
tray plug drench:
10.2 mL/ 1000 plants		 21
  • Gloves must be worn at transplanting.
  • Do not apply more than once per season as a soil application.
  • Do not follow with any subsequent field drench or foliar application of a group 4 insecticide.

Admire 240 F

(imidacloprid)

Group 4

Post-transplant soil application:

6.0 mL per 100 m row

(see Rate Conversion Chart of label for row spacing calculations)

 21
  • Use one of the following methods:
  • Seedlings or established transplants: apply in 200 L/ha (80 L/ac) of water as a subsurface side-dress on both sides of each row. Product must be incorporated into the root zone.
  • Post-seeding drench or transplant-water drench: use higher water volumes to thoroughly wet the soil.
  • Do not apply more than once per season.
  • Do not follow with any subsequent foliar application of a group 4 insecticide.

Alias 240 C

(imidacloprid)

Group 4

Post-transplant field drench:

650 mL per ha

(see Rate Conversion Chart of label for linear application for common row spacing)

 21
  • Apply in-furrow at transplanting as a drench in the transplanting water or banded over the row directed at the root zone.
  • Do not make more than one field drench in the same field per season.
  • Do not make any subsequent application of a group 4 insecticide.

Admire 240 F/ Alias 240 C

(imidacloprid)

Group 4
 200 mL/ha
(80 mL/acre)		 7
  • Apply as a foliar spray after transplanting.
  • For Admire 240F, repeat using a 5 day interval.
  • Do not make more than 2 applications per year.
  • Do not make a foliar application following a soil or in-furrow treatment using a Group 4 insecticide.
  • Highly toxic to bees.  Do not apply or allow to drift to blooming crops or weeds if bees are visiting the treatment area.
  • Do not re-enter treated area for 24 hours.

Assail 70 WP

(acetamiprid)

Group 4		 56 to 86 grams/ha
(23 to 35 grams/acre)

Apply in 200 L/ha (80 L/acre) of water 		7
  • Thorough coverage is important.
  • Repeat at a 7 day interval.
  • Do not use more than 5 times per season, do not exceed a total of 430 g of product per hectare (174 g/acre) per season.
  • Do not enter treated area for 12 hours.

Actara 240 SC

(thiamethoxam)
 
Group 4
 375 to 625 mL/ha
(152 to 253 mL/acre)		 N/A
  • Make an in-furrow application at the seeding or transplant depth or a narrow surface band above the seedline during planting.
  • For a surface application, incorporate to the seeding depth with irrigation within 24 hours after planting.
  • Do not apply more than 625 mL/ha (253 mL/acre) per year.
  • Do not follow with any subsequent foliar applications of a group 4 insecticide.
  • Do not re-enter treated area for 12 hours.

Actara 25 WG

(thiamethoxam)

Group 4		 105 g/ha
(42 g/acre)

Apply in 100L/ha (40 L/acre) of water 		7
  • Maximum of 2 foliar applications per season.
  • Repeat using a 7 day interval.
  • Do not use if following an in-furrow or soil application of Actara 240 SC.
  • Highly toxic to bees.  Do not apply if flowering weeds are present and if bees are foraging in or adjacent to the treatment area.
  • Do not re-enter treated area for 12 hours.

Closer SC

(sulfoxaflor)
 
Group 4C
100 to 150 mL/ha
(40 to 60 mL/acre)
 
Apply in 100 L/ha (40 L/acre) of water
 3
  • Do not use in greenhouses.
  • Do not make more than 2 applications per growing season.
  • Repeat at a 7 day interval.
  • Do not apply more than 300 mL/ha (120 mL/acre) per growing season.
  • Do not apply during crop flowering period or when flowering weeds are present in treatment area.
  •  Observe a plantback interval of 30 days for crops not on this label. 
  • Do not enter treated area for 12 hours.

Sivanto Prime

(flupyradifurone)

 

Group 4D

500 to 750 mL/ha
(200 to 300 mL/acre)


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

 1
  • Do not use in the greenhouse.
  • Repeat at a 7 day interval.
  • Do not exceed a total of 2000 mL/ha (810 mL/acre) of product per season.
  • Toxic to bees.  Do not apply if flowering weeds are present and bees are visiting the treatment area.
  • Do not enter treated areas for 12 hours.

Fulfill 50 WG

(pymetorzine)

Group 9B

Note:  no longer produced

 193 g/ha
(78 g/acre)

Apply in 100L/ha (40L/acre) of water.		 14
  • Maximum of 2 applications per season.
  • Apply at a 7 day spray interval.
  • Apply with a non-ionic adjuvant such as: Agral 90, Ag Surf, LI 700, or Sylgard 309 to improve performance under drought conditions.
  • Observe a 30 day plant back restriction for all crops.
  • Do not enter treated area for 12 hours.

Versys

(afidopyropen)

Group 9D

100 mL/ha

(40 mL/acre)

Apply in 100 L/ha (40 L/acre) of water		 0
  • Do not apply in greenhouses.
  • Apply as a groundspray.
  • Repeat using a 7 day interval.
  • Do not apply more than 4 times per year.
  • Ensure thorough coverage.
  • Do not apply more than 1.25 L/ha (506 mL/acre) per year.
  • Observe a plantback interval of 30 days for crops not listed.
  • Do not re-enter for 12 hours.

Movento 240 SC

(spirotetramat)

Group 23		 220 to 365 mL/ha
(90 to 150 mL/acre)

Apply in 300 L/ha (120 L/acre) of water 		3
  • Repeat at 7 day intervals as needed.
  • Maximum allowed per crop season: 730 mL/ha (295 mL/acre).
  • Do not enter treated area for 12 hours.
  • 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).

Exirel

(cyantraniliprole)
 
Group 28
500 to 1500 mL/ha
(200 to 605 mL/acre)
 
Apply in 100 L/ha (40 L/acre) of water
1
  • 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.

Beleaf 50SG

(flonicamid)

Group 29		 120 to 160 g/ha
(50 to 65 g/acre)

Apply in 94 L/ha (38 L/acre) of water		 0
  • Repeat at 7 day intervals.
  • Do not apply more than 3 times per year.
  • Do not apply more than 600 g/ha (240 g/ac) of product per season.
  • Do not enter treated area for 12 hours.
  • Also suppresses lygus bug.  Check label for rate.

*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).

 

Lettuce root aphids

The lettuce root aphid is a “woolly” aphid with a mealy-white to light-gray appearance. It lives on several species of poplar trees and on lettuce roots. It starts out on poplar trees in spring where large numbers develop in oblong swellings (galls) on poplar leaf petioles.

In early summer these galls burst open, and aphids fly to surrounding lettuce fields where they colonize lettuce roots. Their feeding causes stunting of plants.

Control

Plantings established during late June and July are especially vulnerable. Keeping the soil moist by timely irrigation will minimize the effect of aphid feeding. 

Note: Foliar-applied products registered for control or suppression of foliar aphids will not be effective against the lettuce root aphid.

 

Leafhoppers (Interior area)

In the Interior, aster leafhoppers from nearby forage crops and weedy areas may carry the aster yellows disease into lettuce and other vegetable crops.

Growers may determine when the leafhoppers are migrating into the field by using yellow sticky traps. If past experience suggests that a chemical control program is warranted, spray at the first sign of adults with a product from the table below.

Chemical control of leafhoppers
Product Rate PHI* Comments

Mako

(cypermethrin)

Group 3
125 mL/ha
(50 mL/acre)
 
Apply in 100 to 500 L/ha (40 to 200 L/ac) of water
 14
  • Do not use in the greenhouse.
  • Repeat using 7 day intervals.
  • Do not make more than 4 applications per year.
  • 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

200 mL//ha
(80 mL/acre)

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

 14
  • Do not use in the greenhouse.
  • Repeat using 7 to 14 day intervals.
  • Do not apply more than 4 times per year.
  • Very toxic to bees. Avoid spraying when bees are foraging.
  • Do not re-enter treated area for 12 hours.

Actara 240 SC

(thiamethoxam)

Group 4		 375 to 625 mL/ha
(152 to 253 mL/acre)		 N/A
  • Make an in-furrow application at the seeding or transplant depth or a narrow surface band above the seedline during planting.
  • For a surface application, incorporate to the seeding depth with irrigation within 24 hours after planting.
  • Do not apply more than 625 mL/ha (253 mL/acre) per year.
  • Do not follow with any subsequent foliar applications of a group 4 insecticide.
  • 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).

 

 

Loopers and other caterpillars

These insect larvae feed on leaves. They are difficult to control when the lettuce head has formed.

Control

When the first caterpillars are expected or seen, use one of the insecticides listed in the table below.

Chemical control of loopers and caterpillars
Product Rate PHI* Comments

Orthene 75 SP

(acephate)

Group 1B		 750 to 1100 g/ha
(300 to 445 g/acre)

Apply in 225 to 1,650 L/ha (90 to 665 L/acre) of water 		7
  • Use on head lettuce only.
  • Do not feed trimmings to livestock or allow animals to graze on treated areas.
  • Do not apply more than 4 times per season.
  • Do not enter treated area for 1 day. For activities involving significant foliar contact, gloves and cotton coveralls must be worn for 2 weeks.

Malathion 85E

(malathion)

Group 1B
735 to 1345 mL/ha
(295 to 545 mL/acre)
 
Apply in 1000 L/ha (405 L/acre) of water
Head: 3
Leaf: 14
  • Controls loopers only.
  • Also controls aphids.  See label.
  • Do not make more than 1 application per year.
  • Provides best control at temperatures 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 24 hours.

Matador 120EC

(lambda-cyhalothrin)

Group 3

 83 mL/ha
(34 mL/acre)

Apply in 500 L/ha (200 L/acre) of water		 3
  • Controls loopers only.
  • Use on head lettuce only.
  • Apply when insects or damage first appear.
  • Allow 7 days between applications and not more than 3 applications per year.
  • Also controls cutworms.
  • Do not enter treated areas for 24 hours.

Silencer 120EC

(lambda-cyhalothrin)

Group 3

 83 mL/ha
(34 mL/acre)

Apply in 500 L/ha (200 L/acre) of water		 3
  • Controls loopers only.
  • Use on head lettuce only.
  • Apply when insects or damage first appear.
  • Allow 7 days between applications and not more than 3 applications per year.
  • Also controls cutworms.
  • Do not enter treated areas for 24 hours.

Entrust 80

(spinosad)
 
Group 5
 
Used in organics
 109 g/ha
(44 g/acre)		 1
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than 3 times per year.
  • 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 enter treated area until residues have dried.

Entrust

(spinosad)
 
Group 5
 
Used in organics
 364 mL/ha
(147 mL/acre)		 1
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than 3 times per year.
  • 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 enter treated area until residues have dried.

Success

(spinosad)

Group 5

 182 mL/ha
(74 mL/acre)		 1
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than 3 times per year.
  • 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 enter treated area until residues have dried.

Delegate WG

(spinetoram)

Group 5		 140 to 200 g/ha
(60 to 80 g/acre)		 1
  • For optimal performance, final solution pH should be in the range of 6 to 8.
  • Apply at egg hatch or to small larvae.
  • Repeat at 5 day intervals.
  • Maximum of 3 applications per year.
  • Toxic to bees. Avoid spraying when bees are foraging.

Minecto Pro

(abamectin/ cyantraniliprole)

Group 6 & 28

370 mL/ha

(150 mL/acre)

Apply in 200 L/ha (80 L/acre) of water 		7
  • Controls loopers only.
  • Use with 0.1 to 0.5% v/v non-ionic surfactant in the spray mixture.
  • Ensure thorough coverage.
  • Repeat using a 7 day interval.
  • Do not apply more than 3 times per season using the high rate.
  • Do not apply more than 5 times per season using the low rate.
  • Do not apply more than 2.010 L/ha (813 mL/acre) per season.
  • Do not apply for 60 days following an in-furrow or soil application or seed piece treatment with any group 28 insecticide.
  • Check label for plantback intervals.
  • Do not re-enter for 12 hours.

XenTari WG

(Bacillus thuringiensis, subsp. aizawai)
 
Group 11
 
Used in organics
500 to 1000 g/ha
(200 to 400 g/acre)
 
Apply in 500 L/ha
(200 L/acre) of water
 0
  • Controls loopers only.
  • Treat larvae at the early instar stage.
  • Repeat at 3 to 14 day intervals.
  • Use enough water to ensure full coverage but not to the point of run off.
  • Larvae must be actively feeding on treated, exposed plant surfaces.
  • Apply in the evening or on a cloudy day.
  • Do not allow spray mixture to stand in the tank for more than 12 hours.
  • XenTari products are OMRI-USA listed.  Check with your certiification body before using in an organic operation.

Intrepid

(methoxyfenozide)

Group 18		 300 to 600 mL/ha
(120 to 240 mL/acre)

Apply in 300 L/ha (120 L/acre) of water		 1
  • Controls loopers only.
  • Apply at first sign of feeding damage.
  • Repeat at 7 to 14 day intervals.
  • Do not re-enter for 12 hours.

Coragen

(chlorantraniliprole)

Group 28		 250 mL/ha
(100 mL/acre)

Apply in 100L/ha (40 L/acre) of water 		1
  • Controls loopers only.
  • Repeat at 3 day intervals.
  • Do not make more than 4 applications per season.
  • Do not enter treated area for 12 hours.

Exirel

(cyantraniliprole)
 
Group 28
250 to 500 mL/ha
(100 to 200 mL/acre)
 
Apply in 100 L/ha (40 L/acre) of water
 1
  • Controls loopers only.
  • Do not make more than 4 applications per growing season.
  • Repeat at 7 day intervals.
  • Do not apply more than 4.5 L/ha (1.8 L/acre) per season.
  • 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.

Harvanta 50SL

(cyclaniliprole)
 
Group 28
0.8 to 1.2 L/ha
(324 to 485 mL/acre)
 
Apply in 200 to 1000 L/ha (80 to 400 L/acre) of water
 1
  • Do not use in the greenhouse.
  • Repeat using a 5 day interval.
  • Do not make more than 6 applications per crop per year.
  • Do not apply more than 4.8 L/ha (1.9 L/acre) per year.
  • Toxic to bees.
  • Observe a plantback interval of 30 days for crops not listed.
  • Do not re-enter treated area for 12 hours.

Loopex

(Autorgrapha californica)

 2.5X1010 to 1X1011 PIBs/400L of water 0
  • Controls loopers only.
  • For use in the greenhouse on plants grown for transplanting.
  • Dilute 50 to 200 mL of product in 400 of water.
  • Apply using high volume spary systems targeting small larvae.
  • To be effective, larvae must ingest foliage with deposits of the product.
  • Repeat every 7 to 14 days.
  • The pH of the solution should range between 5 and 8.

Dipel 2X DF

(Bacillus thuringiensis)
 
Used in organics
 275 to 550 g/ha
(110 - 220 g/acre)		 0
  • Controls loopers only.
  • It is most effective when insects are young.
  • Use sufficient spray volume to ensure uniform deposition on all plant surfaces.
  • Dipel products are OMRI-USA listed.  Check with your certiification body before using in an organic operation.

Bioprotec CAF

(Bacillus thuringiensis)
 1.4 to 2.8 L/ha
(0.6 to 1.1 L/acre)		 0
  • It is most effective when insects are young.
  • Use sufficient spray volume to ensure uniform deposition on all plant surfaces.

*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
OMRI-USA = Organic Materials Review Institute of USA
 

Slugs

These slow-moving, soft-bodied, slimy, legless creatures are found in various sizes up to 10 cm. They eat holes in leaves and leave trails of slime. Damp conditions favour slugs.

Control

Where slugs may be a problem, treatment should be applied before planting or while plants are in the seedling stage (see table below).

Chemical control of slugs
Product Rate PHI* Comments

Commercial Bait

(metaldehyde)		 See label for rate. See label.
  • Do not use on leaf lettuce.
  • Treatments should be made in the evening to the soil between the rows and the headlands.
  • Avoid direct application to plants.
  • Do not apply to head lettuce after the head begins to form.

Deadline M-PS

(metaldehyde)		 14 to 27.5 kg/ha
(5.6 to 11 kg/acre)		 6
  • Apply as soil surface treatment.
  • Do not contaminate edible portion of the plant.
  • Do not apply directly to food crops.
  • Apply at a 14 day spray interval.
  • Do not apply more than 3 times per season.
  • Is very toxic to pets and other animals.

Sluggo Professional

(Ferric phosphate)
 
Used in organics.
 25 to 50 kg/ha
(10 to 20 kg/acre)		 0
  • Best applied in evenings to moist soil.
  • Do not place in piles.
  • Sluggo Professional (PCP# 30025) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Slug and Snail Bait II

(ferric sodium EDTA)		 11 – 22 kg/ha
(4.4 – 8.9 kg/acre)		 0
  • Early morning or evening is best time to apply.
  • Repeat applications at 14 day intervals.

*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
OMRI-USA = Organic Materials Review Institute of USA
 

Pea leafminer (Liriomyza huidobrensis)

Chemical control of pea leafminer (Liriomyza huidobrensis)
Product Rate PHI* Comments

Assail 70 WP

(acetamiprid)

Group 4		 86 grams/ha
(35 grams/acre)

Apply in 200 L/ha (80 L/acre) of water 		7
  • Thorough coverage is important.
  • Repeat at a 7 day interval.
  • Do not use more than 5 times per season, do not exceed a total of 430 g of product per hectare (174 g/acre) per season.
  • Do not enter treated area for 12 hours.

Actara 240 SC

(thiamethoxam)

Group 4		 375 to 625 mL/ha
(152 to 253 mL/acre)		 N/A
  • Make an in-furrow application at the seeding or transplant depth or a narrow surface band above the seedline during planting.
  • For a surface application, incorporate to the seeding depth with irrigation within 24 hours after planting.
  • Do not apply more than 625 mL/ha (253 mL/acre) per year.
  • Do not follow with any subsequent foliar applications of a group 4 insecticide.
  • Do not re-enter treated area for 12 hours.

Citation 75WP

(cyromazine)

Group 17
188 g (2.5 soluble bags)/ha 
(76 g (1 soluble bag)/acre

Apply in 200 L/ha (80 L/acre) of water
7
  • Apply as a foliar spray at first appearance of larvae.
  • Re-apply as needed, allowing at least 7 days between applications.
  • Do not make more than 5 applications per season.

Coragen

(chlorantraniliprole)

Group 28		 250 to 375 mL/ha
(100 to 150 mL/acre)

Apply in 100 L/ha (40 L/acre) of water. 		1
  • Repeat at 3 day intervals.
  • Do not make more than 4 applications per season.
  • Do not apply more than 1 L/ha (400 mL/ac) per season.
  • For control of Black Cutworm, use the lower rate and apply to smaller plants or when lower portions of the plant can receive adequate coverage.
  • Do not re-enter treated area for 12 hours.

Exirel

(cyantraniliprole)
 
Group 28
1000 to 1500 mL/ha
(405 to 605 mL/acre)
 
Apply in 100 L/ha (40 L/acre) of water
1
  • Controls Dipteran leafminer larvae.
  • 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.

Harvanta 50SL

(cyclaniliprole)

Group 28

1.2 L/ha
(485 mL/acre)

Apply in 200 to 1000 L/ha (80 to 400 L/acre) of water		 1
  • Do not use in the greenhouse.
  • Repeat using a 5 day interval.
  • Do not make more than 6 applications per crop per year.
  • Do not apply more than 4.8 L/ha (1.9 L/acre) per year.
  • Toxic to bees.
  • Observe a plantback interval of 30 days for crops not listed.
  • 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).

 

Lettuce disease management

Expand All | Collapse All
 

Anthracnose

Small, tan to straw-coloured spots on the lower leaves and mid-ribs. The leaf spots eventually fall out leaving a shot-hole appearance. This disease frequently occurs during unusually wet springs.

Control

  • Clean up all lettuce residue in and around greenhouses or cold frames where early lettuce transplants are started.
  • Avoid unnecessary overhead watering.
  • Turn under crop residue in the field after harvest.
  • Fields which produced a seriously diseased crop should be rotated out of lettuce for at least one year.
 

Bacterial slime rot

Occurs as a wet, slimy decay on lettuce in the field, in transit or in the markets. Usually the large internal leaves are affected first.

Control

  • Do not crowd plants.
  • Avoid overwatering.
  • Harvest as soon as mature.
  • Pre-cool harvested heads to 1°C and keep cool.
 

Bottom rot

The common soil fungus, Rhizoctonia, infects the basal leaves of lettuce heads as they approach maturity causing rust-coloured, sunken lesions which first appear on the midrib. Under warm, damp conditions the lesions can enlarge and rot the entire midrib. There are no obvious spores or mycelium associated with bottom rot. The fungus does, however, overwinter by producing sclerotia.

Control

  • Avoid growing head lettuce in fields with a history of bottom rot.
  • Lettuce types with an upright growth habit are more likely to escape infection.
  • Rotate with grasses, cereals or legumes.

Chemical control of bottom rot (Rhizoctonia solani)
Product Rate PHI* Comments

Taegro

(Bacillus subtilis)
 
Used in organics.

190 g/ha (77 g/acre)

Apply in 935.4 L/ha (378.6 L/acre) of water

 0
  • Suppression only.
  • Apply to the plant base and soil/growing medium surface to protect the contact between soil and leaf tissue.
  • Water-in product after applying.
  • Repeat at 7 day intervals.
  • Taegro (PCP# 30720) 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

 

Damping-off/stunt

(Pythium)

Pythium species in soil cause damping off of seedlings under wet conditions. If Pythium invades the crown, plants become stunted. Ridomil Gold 1G is registered on head lettuce as a granular application at seeding for control of damping-off and stunt. Growers wishing to evaluate this treatment should follow the same procedure as suggested for the cavity spot of carrot treatment (see Carrot section). The recommended rate is 115 g/100 m of row or 25 kg/treated ha (10.1 kg/treated acre). Make only one application per year, at seeding.

Torrent 400 SC (cyazofamid) is also registered on greenhouse lettuce transplants for control of Pythium Damping-Off and Root Rot.

 

Drop

(White mould)

Drop of lettuce, caused by Sclerotinia, is so-called because the outer leaves of infected plants tend to collapse and lie flat on the ground. Uprooting such plants reveals white mycelium and in later stages, dark sclerotia. The large (5 – 15 mm) sclerotial form of the fungus tends to predominate in the spring and spores can blow into a crop from adjacent fields and waste areas. The small (0.5 – 2 mm) sclerotial form of the disease infects directly from contact with the soil under moist conditions at any time during the growing season.

Control

  • Rotate with corn, cereals, forages, onions or potatoes.
  • Roguing is an effective means of reducing inoculum for future crops only with the small sclerotial form.
  • Incorporate diseased crop refuse promptly to reduce sclerotial production.
  • Do not dump infected produce near production fields as the large sclerotial form produces spores which can be blown back into the field.
  • Prolonged flooding will reduce survival of sclerotia.
  • See tables below. Because of its high cost, it is only recommended in fields with a history of drop or in situations of severe disease pressure.
  • Rovral WP applied for grey mould control may also help to control drop.

Chemical control of drop (white mould)
Product Rate PHI* Comments

Serenade Opti

(Bacillus subtilis)

Used in organics

 0.6 to 1.7 kg/ha
(240 to 690 g/acre)		 0
  • Suppression only.
  • Make first application at planting or immediately following planting, but prior to crop emergence.
  • Make second application within 7 days of thinning, with a directed spray to ensure thorough coverage of lower leaves and surrounding soil surface,.
  • Repeat using a 10 to 14 day interval.
  • Serenade Opti (PCP# 31666) are OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Lance WDG

(boscalid)

Group 7

 385 g/ha
(154 g/acre)

Apply in 100 L/ha (40 L/acre) of water		 14
  • Suppression only.
  • Direct-seeded:  Apply 1 to 2 days after thinning. If required apply 10 to 20 days later.
  • Transplanted:  Apply 7 to 10 days after transplanting. If required, apply 10 to 20 days later.
  • Do not apply more than 2 times per season.
  • Do not enter treated for 12 hours.
  • For crops not on the label, observe a plant back interval of 14 days.

Cantus WDG

(boscalid)

Group 7

 385 g/ha
(154 g/acre)

Apply in 100 L/ha (40 L/acre) of water 		14
  • Suppression only.
  • Direct-seeded:  Apply 1 to 2 days after thinning. If required apply 10 to 20 days later.
  • Transplanted:  Apply 7 to 10 days after transplanting. If required, apply 10 to 20 days later.
  • Do not apply more than 2 times per season.
  • Do not enter treated for 12 hours.
  • For crops not on the label, observe a plant back interval of 14 days.

Sercadis

(fluxapyroxad)

Group 7

 250 to 333 mL/ha
(101 to 135 mL/acre)

Apply in 100 L/ha (40 L/acre) of water		 1
  • Suppression only.
  • Repeat at 7 to 14 day intervals.
  • Do not make more than 3 applications per season.
  • Do not apply more than 1.0 L/ha (405 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.

Isofetamid 400SC

(isofetamid)

Group 7

0.90 L/ha
(0.37 L/acre)

 14
  • For water volume, see label details.
  • Direct seeded:  make the 1st application after emergence or thinning.
  • Transplanted lettuce:  make the 1st application immediately after transplanting.
  • Repeat at a 14 day interval.
  • Do not make more than 2 applications per year.
  • Observe a plantback interval of 30 days for crops not listed.
  • Do not re-enter treated area for 12 hours.

Kenja 400SC

(isofetamid)

Group 7

 0.90 L/ha
(0.37 L/acre)		 14
  • For water volume, see label details.
  • Direct seeded:  make the 1st application after emergence or thinning.
  • Transplanted lettuce:  make the 1st application immediately after transplanting.
  • Repeat at a 14 day interval.
  • Do not make more than 2 applications per year.
  • Observe a plantback interval of 30 days for crops not listed.
  • Do not re-enter treated area for 12 hours.

Miravis Prime

(pydiflumetofen & fludioxonil)

Group 7 & 12		 0.8 to 1.0 L/ha
(324 to 404 mL /acre)

Apply in 150 L/ha (60 L/acre) of water 		3
  • Do not use in the greenhouse.
  • Apply to transplanted crops immediately after transplanting.
  • Apply to direct-seeded crops immediately after emergence.
  • Make a 2nd application, using no closer than a 7 day interval, if soil is disturbed by cultivation or thinning or if necessary.
  • Do not make more than 2 consecutive applications before switching to a non-Group 7 & 12 fungicide.
  • For any repeat applications, use a 7 day interval.
  • Do not apply more than 2.0 L/ha (809 mL/ac) per season.
  • See label for details on plantback interval.
  • Do not re-enter treated area for 12 hours.

Double Nickel 55

(Bacillus amyloliqufaciens strain D747)

Group 44

1 to 2.5 kg/ha
(400 to 1000 g/acre)

For smaller plants or low disease pressure:  0.2 to 1 kg/ha (80 to 400 g/acre)

 0
  • Suppression only.
  • Apply as a foliar spray to head formation.
  • Repeat at 3 to 10 day intervals.
  • Do not use highly alkaline or highly acidic water to mix sprays.
  • If necessary, use a buffering agent to maintain a pH of 6 to 8 in the water of the tank. 
  • Do not re-enter treated area for 4 hours

Double Nickel LC

(Bacillus amyloliqufaciens strain D747)

Group 44

5 to 12.5 L/ha
(2 to 5.0 L/acre)

For smaller plants or low disease pressure:   1 to 5 L/ha ( 0.4 to 2 L/acre)

 0
  • Suppression only.
  • Apply as a foliar spray to head formation.
  • Repeat at 3 to 10 day intervals.
  • Do not use highly alkaline or highly acidic water to mix sprays.
  • If necessary, use a buffering agent to maintain a pH of 6 to 8 in the water of the tank. 
  • Do not re-enter treated area for 4 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

 

Downy mildew

(Bremia)

This fungus infects lettuce leaves during cool, damp weather in the spring and again in the fall causing irregularly-shaped yellow to brown lesions. The undersides of the lesions may be covered with glistening white spores. Early infections at the seedling stage can cause stunting and death of plants.

Control

  • Avoid locating early and late plantings in fields with a history of downy mildew.
  • Turn under diseased crop residues promptly to hasten breakdown of the fungus.
  • Plant resistant varieties such as Patriot, Calgary and El Dorado for the harvest period from August to the end of the season.
  • If a fungicide program is to be used it must begin before the disease becomes well established as it is only preventive, not curative. See table below.

Chemical control of downy mildew
Product Rate PHI* Comments

Ridomil Gold MZ 68WP

(metalaxyl-M/mancozeb)

Group 4M

Note:  no longer produced.  Registration expires April 2023

 2.5 kg/ha
(1.0 kg/acre)		 14
  • For use on head lettuce only.
  • Apply every 14 days beginning at thinning for a maximum of 3 applications per crop.
  • While it is highly effective against susceptible isolates of the fungus, resistance builds up rapidly and has already been identified in Cloverdale.
  • Do not use on soils with less than 2 percent organic matter or in areas where the water table may be high.
  • Must be applied before the outbreak of the disease.
  • Do not enter treated area for 24. hours.

Diplomat 5SC

(polyoxin D zinc salt)
 
Group 19
463 to 926 mL/ha
(187 to 375 mL/acre)
 0
  • Suppression only.
  • Repeat using a 7 to 14 day interval.
  • Do not apply more than 2.8 L/ha (1.1 L/acre) per season or 12 months.
  • May be used in the greenhouse.

Torrent

(cyazofamid)
Group 21
 0.2 L/ha
(80 mL /acre)

Apply in 200 to 500 L/ha (80 to 200 L/acre) of water		 0
  • Suppression only.
  • Apply as a foliar broadcast or spray directed at the base of the plant.
  • Repeat using a 7 to 14 day interval.
  • Do not apply more than 6 times per crop per year.
  • Tankmix with a non-ionic or organosilicone surfactant such as Sylgard 309 at the manufacturer's label recommendations.
  • Observe a plantback interval of 30 days for crops not listed.
  • Do not enter treated area for 12 hours.

Orondis

(oxathiapiprolin)

Group 49

75 to 350 mL/ha (70 to 140 mL/acre

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

 0
  • Repeat at 5 to 14 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.

Phostrol

(mono- and dibasic sodium, potassium, and ammonium phosphites)

 

Group 33

2.9 to 5.8 L/ha (1.2 to 2.3 L/acre)

Apply in 225 L/ha (90 L/acre) of water

 0
  • Repeat at 7 to 14 day intervals.
  • Do not make more than 7 applications per season.
  • Do not re-enter treated area for 12 hours.

Confine Extra        

(mono- and di-potassium salts of phosphorous acid)

Group 33

3 to 7 L/ha
(1.2 to 2.8 L  /acre)

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

 1
  • Suppression only.
  • Repeat using a 7 to 14 day interval.
  • Do not make more than 6 applications per growing season.
  • Tankmixing with pesticide products containing a metal base and/or micronutrients may not be compatible and could potentially cause plant injury.  See label for details.
  • Also suppresses Bacterial Leaf Spot (Xanthomonas campestris pv. vitians) in leaf lettuce - at the high rate and using a 7 day application interval.  See label for details. 

Aliette WDG

(fosetyl-aluminum)

Group 33

2.8 kg/ha
(1.1 L/acre)

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

 7
  • Do not make more than 5 applications per year.
  • May cause phytotoxicity when mixed with adjuvants which enhance pesticide penetration.
  • Do not enter treated areas 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 		1
  • Use a non-ionic adjuvant (0.125% v/v).
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than 4 times per year.
  • Do not apply to greenhouse-grown seedlings to be transplanted in the field, until after they have been transplanted out.
  • 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.
  • Tankmix with another fungicide active against downy mildew.
  • Repeat at 5 to 10 day spray intervals.
  • Do not make more than 5 applications per season.
  • Do not re-enter for 2 days for hand-harvesting and for all other activities do not re-enter 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.
  • Do not apply with adjuvant.
  • Do not re-enter treated area for 12 hours.

Presidio

(fluopicolide)

Group 43

 220 to 292 mL/ha
(89 to 118 mL/acre)

Apply in 200 to 1000 L/ha
(80 to 405 L/acre) of water		 2
  • Tank-mix with a product that has a different group number listed in this table for downy mildew, such as Aliette.
  • Follow most restrictive directions including rate, PHI and re-entry interval.
  • Repeat using a 7 to 10 day interval.
  • Do not apply more than 4 times per season.
  • Maximum of 880 mL/ha (356 mL/acre) per season.
  • Do not enter treated for 12 hours.

Double Nickel 55

(Bacillus amyloliqufaciens strain D747)

Group 44

 1 to 2.5 kg/ha
(400 to 1000 g/acre)		 0
  • Suppression only.
  • Repeat at 7 to 10 day intervals.
  • Do not use highly alkaline or highly acidic water to mix sprays.
  • If necessary, use a buffering agent to maintain a pH of 6 to 8 in the water of the tank.
  • Do not re-enter treated area for 4 hours.

Double Nickel LC

(Bacillus amyloliqufaciens strain D747)

Group 44

 5 to 12.5 L/ha
(2 to 5.1 L/acre)		 0
  • Suppression only.
  • Repeat at 7 to 10 day intervals.
  • Do not use highly alkaline or highly acidic water to mix sprays.
  • If necessary, use a buffering agent to maintain a pH of 6 to 8 in the water of the tank.
  • Do not re-enter treated area for 4 hours.

Serenade Opti

(Bacillus subtilis)
Used in organics
 1.7 to 3.3 kg/ha
( 690 to 1300 g/acre)		 0
  • Suppression only.
  • 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.

*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

 

Grey mould rot

(Botrytis)

Grey mould is a very common fungus which sporulates profusely on dead and dying plant material. It is favoured by cool, wet conditions and on lettuce is most damaging in greenhouses and in the spring and fall crops outdoors.

Control

  • Improve air and soil drainage.
  • Plow down crop refuse promptly.
  • Do not over-fertilize with nitrogen, but provide adequate calcium nutrition.
  • See table below for the recommended fungicide.

Chemical control of grey mould rot
Product Rate PHI* Comments

Botector

(Aureobasidium pullulans DSM 14940 & DSM 14941)
 1 kg/ha
(0.4 kg/acre)

Apply in 500 to 2000 L/ha (200 to 800 L/acre) water		 0
  • Suppression only.
  • May be used in the greenhouse.
  • Apply soon after emergence or transplant.
  • Repeat applications using a 7 day interval.
  • Spray plants to run-off.
  • Keep water temperature below 25ºC.
  • Apply in the morning or evening hours and during cool temperatures.
  • Do not allow mixed spray solution to stand overnight or for more than 8 hours. 
  • Do not re-enter treated area for 4 hours.

Serenade Opti

(Bacillus subtilis)

Used in organics

 0.6 to 1.7 kg/ha
(240 to 690 g/acre)		 0
  • Suppression only.
  • Repeat at 7 to 10 intervals.
  • Serenade Opti  (PCP# 31666) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Lance WDG

(boscalid)

Group 7

 285 g/ha
(114 g/acre)

Apply in 100 L/ha (40 L/acre) of water 		14
  • Direct-seeded:  Apply 1 to 2 days after thinning. If required apply again 10 to 20 days later.
  • Transplanted:  Apply 7 to 10 days after transplanting. If required, apply again 10 to 20 days later.
  • Do not apply more than 2 times per year.
  • Do not enter treated area for 12 hours.
  • For crops not listed, observe plant back interval of 14 days.

Cantus WDG

(boscalid)

Group 7

 285 g/ha
(114 g/acre)

Apply in 100 L/ha (40 L/acre) of water 		14
  • Direct-seeded:  Apply 1 to 2 days after thinning. If required apply again 10 to 20 days later.
  • Transplanted:  Apply 7 to 10 days after transplanting. If required, apply again 10 to 20 days later.
  • Do not apply more than 2 times per year.
  • Do not enter treated area for 12 hours.
  • For crops not listed, observe plant back interval of 14 days.

Fontelis

(penthiopyrad)

Group 7

 1.25 to 1.75 L/ha
(500 to 710 mL/acre)

Apply in 110 L/ha (45 L/acre) of water		 3
  • Also suppresses Sclerotinia drop.
  • Repeat at 7 to 10 day intervals.
  • Do not apply more than 5.25 L/ha (2.2 L/acre) per season.
  • Do not make more than 2 sequential applications before switching to a fungicide with a different mode of action.
  • Do not re-enter for 12 hours.

Miravis Prime

(pydiflumetofen & fludioxonil)

Group 7 & 12		 0.8 to 1.0 L/ha
(324 to 404 mL /acre)

Apply in 150 L/ha (60 L/acre) of water 		3
  • Suppression only.
  • Do not use in the greenhouse.
  • Repeat using a 7 to 10 day interval.
  • Do not make more than 2 consecutive applications before switching to a non-Group 7 & 12 fungicide.
  • Do not apply more than 2.0 L/ha (809 mL/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).

 

Tipburn

Tipburn is a physiological disorder that is related to calcium deficiency and is made worse by high soil fertility and high temperatures. The initial symptoms of tipburn are small, dark-brown spots along the margins of the interior or exterior head leaves. These spots later merge and the entire margin becomes brown.

Tipburn is more serious when it occurs on the internal leaves of the head because it cannot be detected and makes the heads unmarketable. The internal dead areas are ideal sites for the development of secondary rots that cause a watery breakdown of the tissue, sometimes known as slime.

Control

There are no procedures that the grower can use that will guarantee freedom from tipburn in field-grown lettuce. The following will minimize the problem:

  • The main control for tipburn has been the use of tolerant varieties, with Alpha, Summertime and Target showing promise locally.
  • Hold nitrogen levels as low as possible for adequate yields. Apply nitrogen in the nitrate form rather than the ammonia form, and do not apply excessive potash (K), magnesium (Mg), or other fertilizers that might compete with calcium uptake. Take soil samples if you are not sure of your pH and calcium levels. Foliar sprays of calcium will not prevent the disorder.
  • Follow good irrigation practices and avoid water stress of the crop.
  • During periods when the lettuce crop is highly susceptible to tipburn, the problem can be lessened by harvesting before full maturity and before tipburn develops sufficiently to reduce the marketability of the lettuce.
 

Root rot - suppression

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.

  • 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.

When applied after sowing seeds or transplanting, Trianum WP (Trichoderma harzianum Rifai strain T22) protects plants against infection by soil-borne pathogens via the root system.  It is a biological fungicide that out-competes plant pathogenic fungi for space and nutrients, colonizing plant roots ahead of pathogens.

  1. Suspend 1 volume of Trianum WP in 5 volumes of water and mix thoroughly. 
  2. Add suspension to required amount of water to make up final drench volume.
  3. Apply immediately after sowing seeds or transplanting.
  4. After sowing: use 1.5 kg/m2 of cultivated area in 1.33 L of water.
  5. After transplanting:  use 6 g in 1 L of water and apply in 500 L/ha of suspension.
  6. Becomes active when soil temperatures are above 10 degrees C and is not effective while soils remain cold.
  7. More effective in neutral or acidic soils.  
  8. Use within 6 months of the date of manufacture.

Chemical control of Pythium root rot (Pythium spp.)
Product Rate PHI* Comments

Torrent

(cyazofamid)
 
Group 21
 30 mL/100L water 40
  • Registered on greenhouse lettuce transplants.
  • Also controls Pythium Damping Off.
  • Apply once in the greenhouse as a soil drench to thoroughly wet the growing medium immediately after seeding.
  • Do not use a surfactant.
  • Do not enter treated area for 12 hours.

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
  • Suppression only.
  • Also suppresses Rhizoctonia damping-off. 
  • Serenade Soil (PCP# 30647) is OMRI-Canada listed.  Check with your certification body before using in an organic operation.

Transplant drench:

  • Apply as a drench at the time of transplanting.
  • Apply at a rate to thoroughly soak the growing media through the root zone or asa drench or directed spray using sufficient water to soak the root zone.

Post-plant applications:

  • 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, root or transplant zone within 24 hours.
  • Repeat at 21 to 28 day intervals.

*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