Lettuce
Growing lettuce
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.
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.
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.
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.
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).
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 |
|
*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).
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 |
|
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 |
|
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 |
|
*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).
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 |
|
*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
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.
Product | Rate | PHI* | Comments |
---|---|---|---|
Cygon 480/ Lagon 480 E(dimethoate) Group 1B |
700 mL/ha |
14 |
|
Dibrom(naled)Group 1B |
1.1 to 1.65 L/ha Apply in 100 to 300 L/ha (40 to 120 L/acre) of water |
4 |
|
Orthene 75 SP(acephate)Group 1B |
563 to 825 g/ha (228 to 335 g/acre) |
7 |
|
Admire 240 F/ Alias 240 C(imidacloprid)
Group 4 |
Pre-transplant tray plug drench: 10.2 mL/ 1000 plants |
21 |
|
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 |
|
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 |
|
Admire 240 F/ Alias 240 C(imidacloprid)
Group 4 |
200 mL/ha (80 mL/acre) |
7 |
|
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 |
|
Actara 240 SC(thiamethoxam)
Group 4
|
375 to 625 mL/ha (152 to 253 mL/acre) |
N/A |
|
Actara 25 WG(thiamethoxam)Group 4 |
105 g/ha (42 g/acre) Apply in 100L/ha (40 L/acre) of water |
7 |
|
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 |
|
Sivanto Prime(flupyradifurone)
Group 4D |
500 to 750 mL/ha
|
1 |
|
Fulfill 50 WG(pymetorzine) Note: no longer produced |
193 g/ha (78 g/acre) Apply in 100L/ha (40L/acre) of water. |
14 |
|
Versys(afidopyropen) Group 9D |
100 mL/ha (40 mL/acre) Apply in 100 L/ha (40 L/acre) of water |
0 |
|
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 |
|
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 |
|
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 |
|
*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).
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.
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.
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 |
|
Up-Cyde 2.5 EC(cypermethrin) Group 3 |
200 mL//ha Apply in 100 to 500 L/ha (40 to 200 L/ac) of water |
14 |
|
Actara 240 SC(thiamethoxam) Group 4 |
375 to 625 mL/ha (152 to 253 mL/acre) |
N/A |
|
*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).
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.
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 |
|
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 |
|
Matador 120EC(lambda-cyhalothrin) Group 3 |
83 mL/ha (34 mL/acre) Apply in 500 L/ha (200 L/acre) of water |
3 |
|
Silencer 120EC(lambda-cyhalothrin) Group 3 |
83 mL/ha (34 mL/acre) Apply in 500 L/ha (200 L/acre) of water |
3 |
|
Entrust 80(spinosad)
Group 5
Used in organics
|
109 g/ha (44 g/acre) |
1 |
|
Entrust(spinosad)
Group 5
Used in organics
|
364 mL/ha (147 mL/acre) |
1 |
|
Success(spinosad) Group 5 |
182 mL/ha (74 mL/acre) |
1 |
|
Delegate WG(spinetoram)Group 5 |
140 to 200 g/ha (60 to 80 g/acre) |
1 |
|
Minecto Pro(abamectin/ cyantraniliprole) Group 6 & 28 |
370 mL/ha (150 mL/acre) Apply in 200 L/ha (80 L/acre) of water |
7 |
|
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 |
|
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 |
|
Coragen(chlorantraniliprole)Group 28 |
250 mL/ha (100 mL/acre) Apply in 100L/ha (40 L/acre) of water |
1 |
|
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 |
|
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 |
|
Loopex(Autorgrapha californica) |
2.5X1010 to 1X1011 PIBs/400L of water | 0 |
|
Dipel 2X DF(Bacillus thuringiensis)
Used in organics
|
275 to 550 g/ha (110 - 220 g/acre) |
0 |
|
Bioprotec CAF(Bacillus thuringiensis)
|
1.4 to 2.8 L/ha (0.6 to 1.1 L/acre) |
0 |
|
*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).
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).
Product | Rate | PHI* | Comments |
---|---|---|---|
Commercial Bait(metaldehyde) |
See label for rate. | See label. |
|
Deadline M-PS(metaldehyde) |
14 to 27.5 kg/ha (5.6 to 11 kg/acre) |
6 |
|
Sluggo Professional(Ferric phosphate)
Used in organics.
|
25 to 50 kg/ha (10 to 20 kg/acre) |
0 |
|
Slug and Snail Bait II(ferric sodium EDTA) |
11 – 22 kg/ha (4.4 – 8.9 kg/acre) |
0 |
|
*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).
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 |
|
Actara 240 SC(thiamethoxam) Group 4 |
375 to 625 mL/ha (152 to 253 mL/acre) |
N/A |
|
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 |
|
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 |
|
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 |
|
Harvanta 50SL(cyclaniliprole) Group 28 |
1.2 L/ha |
1 |
|
*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
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.
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.
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.
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 |
|
*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
(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.
(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.
Product | Rate | PHI* | Comments |
---|---|---|---|
Serenade Opti(Bacillus subtilis) Used in organics |
0.6 to 1.7 kg/ha (240 to 690 g/acre) |
0 |
|
Lance WDG(boscalid) |
385 g/ha (154 g/acre) Apply in 100 L/ha (40 L/acre) of water |
14 |
|
Cantus WDG(boscalid) |
385 g/ha (154 g/acre) Apply in 100 L/ha (40 L/acre) of water |
14 |
|
Sercadis(fluxapyroxad) |
250 to 333 mL/ha (101 to 135 mL/acre) Apply in 100 L/ha (40 L/acre) of water |
1 |
|
Isofetamid 400SC(isofetamid) Group 7 |
0.90 L/ha |
14 |
|
Kenja 400SC(isofetamid) Group 7 |
0.90 L/ha (0.37 L/acre) |
14 |
|
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 |
|
Double Nickel 55(Bacillus amyloliqufaciens strain D747) Group 44 |
1 to 2.5 kg/ha For smaller plants or low disease pressure: 0.2 to 1 kg/ha (80 to 400 g/acre) |
0 |
|
Double Nickel LC(Bacillus amyloliqufaciens strain D747) Group 44 |
5 to 12.5 L/ha For smaller plants or low disease pressure: 1 to 5 L/ha ( 0.4 to 2 L/acre) |
0 |
|
*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
(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.
Product | Rate | PHI* | Comments |
---|---|---|---|
Serenade Opti(Bacillus subtilis)
Used in organics
|
1.7 to 3.3 kg/ha ( 690 to 1300 g/acre) |
0 |
|
Oxidate 2.0(hydrogen peroxide & peroxyacetic acid) Used in organics |
Dilute 1.0 L product in 100 L water (1.0% v:v) | 0 |
|
Ridomil Gold MZ 68WP(metalaxyl-M/mancozeb) Note: no longer produced. Registration expires April 2023 |
2.5 kg/ha (1.0 kg/acre) |
14 |
|
Diplomat 5SC(polyoxin D zinc salt)
Group 19
|
463 to 926 mL/ha
(187 to 375 mL/acre)
|
0 |
|
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 |
|
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 |
|
Confine Extra(mono- and di-potassium salts of phosphorous acid) Group 33 |
3 to 7 L/ha Apply in 100 L/ha (40 L/acre) of water. |
1 |
|
Aliette WDG(fosetyl-aluminum) |
2.8 kg/ha Apply in 150 L/ha (60 L/acre) of water |
7 |
|
Revus(mandipropamid) |
400 to 600 mL/ha (160 to 240 mL/acre ) Apply in 100 L/ha (40 L/acre) of water |
1 |
|
Forum(dimethomorph)
Group 40
|
450 mL/ha (182 mL/acre) Apply in 200 L/ha (80 L/acre) of water. |
0 |
|
Zampro(ametoctradin & dimethomorph) Group 40 & 45 |
1.0 L/ha (400 mL/acre) Apply in 200 L/ha (80 L/acre) of water. |
0 |
|
Presidio(fluopicolide) |
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 |
|
Double Nickel 55(Bacillus amyloliqufaciens strain D747) Group 44 |
1 to 2.5 kg/ha (400 to 1000 g/acre) |
0 |
|
Double Nickel LC(Bacillus amyloliqufaciens strain D747) Group 44 |
5 to 12.5 L/ha (2 to 5.1 L/acre) |
0 |
|
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 |
|
*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)
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.
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 |
|
Serenade Opti(Bacillus subtilis) Used in organics |
0.6 to 1.7 kg/ha (240 to 690 g/acre) |
0 |
|
Lance WDG(boscalid) |
285 g/ha (114 g/acre) Apply in 100 L/ha (40 L/acre) of water |
14 |
|
Cantus WDG(boscalid) |
285 g/ha (114 g/acre) Apply in 100 L/ha (40 L/acre) of water |
14 |
|
Fontelis(penthiopyrad) |
1.25 to 1.75 L/ha (500 to 710 mL/acre) Apply in 110 L/ha (45 L/acre) of water |
3 |
|
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 |
|
*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 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.
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.
- Suspend 1 volume of Trianum WP in 5 volumes of water and mix thoroughly.
- Add suspension to required amount of water to make up final drench volume.
- Apply immediately after sowing seeds or transplanting.
- After sowing: use 1.5 kg/m2 of cultivated area in 1.33 L of water.
- After transplanting: use 6 g in 1 L of water and apply in 500 L/ha of suspension.
- Becomes active when soil temperatures are above 10 degrees C and is not effective while soils remain cold.
- More effective in neutral or acidic soils.
- Use within 6 months of the date of manufacture.
Product | Rate | PHI* | Comments |
---|---|---|---|
Torrent(cyazofamid)
Group 21
|
30 mL/100L water | 40 |
|
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 |
Transplant drench:
Post-plant applications:
|
*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