|
Chapter 20 Lettuce and Endive
Link to IPM Elements for lettuce
Link to New
York Lettuce Crop Profile
Link to Resource
Guide for Organic Insect and Disease Management
Recommended
Varieties
|
Lettuce
|
|
|
Butterhead (Boston)
|
Leaf |
Ermosa (48)
|
Grand Rapids (45)
|
Nancy (52)
|
Red Sails (45)
|
Buttercrunch (60)
|
Tierra
|
Summer Bibb (65)
|
New Red Fire (red) (48)
|
Tania
(65)
|
Sierra (red)
|
Esmerelda
(68)
|
Slobolt (50)
|
Dark Green Boston (75)
|
Waldmann's Green
(50)
|
|
Romaine (Cos)
|
Endive |
Dark Green Cos
|
Florida Deep
Heart (75)
|
Green Towers (70)
|
Full Heart Batavia
(80)
|
Ideal Cos (75)
|
Green Curled
Ruffel
|
Parris Island Cos (76)
|
Salad King (92)
|
| Crisphead (Iceberg)
|
|
Great Lakes
|
|
Ithaca
(75)
|
|
Onondaga
|
|
Raleigh
|
|
South Bay
|
|
|
|
Numbers in parentheses: Approximate
days to harvest.
|
Table of Boston/butterhead disease resistant varieties
Table of green leaf disease resistant varieties
Table of red leaf disease resistant varieties
Planting
Methods
Lettuce is a cool-season crop, and high temperatures
(particularly at night) in midsummer are very damaging, promoting such
disorders as premature bolting, tipburn, and brown rib. Crisphead (iceberg)
lettuce is especially sensitive to heat, although some new varieties are
more tolerant.
Once-over harvesting is done on most large commercial
acreage, so every effort must be made to promote uniform maturity. Although
lettuce can be transplanted readily, most lettuce in New York is direct
seeded, usually with pelleted seed in precision seeders. Irrigation immediately
following seeding promotes uniform emergence. Where irrigation is not
possible, deep plowing followed immediately by fitting and seeding is
helpful. Rows generally are spaced about 15 inches apart, and in-row spacing
is determined by variety and desired size of marketed lettuce. Uniform
spacing is important for achieving uniform maturity.
Growers are encouraged to rotate lettuce with another
crop whenever possible. This aids in the management of many pests that
affect lettuce. Double-cropping lettuce on the same field may greatly
increase problems such as Sclerotinia drop, corky root rot, root knot
nematode, and virus diseases in the second planting.
Crop rotation and disease management article
Fertility
Maintain a pH of 6.0 to 6.2 on mineral soils. Consider
liming if pH falls below 5.5 on muck soil. If mucks require lime for lettuce
production, avoid turning up more than one inch of new muck in any one
plowing. Liming to a pH higher than 5.6 is not advisable on muck. See
Table 20.1 for the recommended rates of nitrogen, phosphorus, and
potassium.
Cornell cover crop decision tool
See Cornell
article on nutrient deficiency symptoms
Go to Cornell Nutrient Analysis Lab website to find out how to get soil samples
tested.
Cornell Soil Health website and manual
SARE Publication: "Building Soils for Better Crops"
SARE publication: "Managing Cover Crops Profitably"
|
| Table
20.1 Recommended nutrients based on soil tests. |
|
|
N
pounds/acre
|
P2O5
pounds/acre
|
|
K2O
pounds/acre
|
Comments |
|
Soil
Phosphorus Level
|
|
Soil
Potassium Level
|
|
|
low
|
med.
|
high
|
|
low
|
med.
|
high
|
|
|
100
(50-100 on muck)
|
120
|
60
|
30
|
|
150
|
100
|
50
|
Total
recommended. |
|
40
|
90
|
50
|
0
|
|
120
|
70
|
0
|
Broadcast
and disk-in. |
|
30
|
30
|
30
|
40
|
|
30
|
30
|
50
|
Apply
in band at planting or drill deep after plowing. |
|
30
|
0
|
0
|
0
|
|
0
|
0
|
0
|
Apply
3 weeks after thinning or setting. Not needed on muck soil. |
Harvesting
Care in harvesting and handling is important for these
crops since they are easily damaged. Noncrisphead varieties are more susceptible
to damage during harvest and transit and therefore have a shorter shelf
life than crisphead varieties. Vacuum cooling and/or contact icing to
remove field heat will improve market quality and shelf life. The use
of top ice when packaging acts to supply moisture and remove heat. Optimum
storage conditions are 32°F and at least 95 percent relative humidity.
Good air flow through and around boxes is essential.
See UC
Davis post harvest guide for crisphead lettuce
See UC
Davis post harvest guide for Romaine lettuce
See Cornell Report:
Food Safety Begins on the Farm
See Cornell
"Smart Marketing" series.
See USDA grade standards for lettuce.
See USDA
Marketing site
See current
wholesale prices from US markets
See "Fresh
Now from New York Farms"
SARE Publication: "Marketing Strategies for Farmers and Ranchers"
SARE Publication: "Direct Marketing Resource Guide"
|
| Table
20.2 Nonpathogenic disorders. |
|
|
Disorder
|
Cause
|
| Tipburn |
Poor water
management/calcium deficiency. Plant tipurn resistant varieties during
warmer parts of growing season. |
|
Poor stand
|
Thermodormancy.
Irrigate after seeding during periods of very hot weather. |
|
Bolting
|
High night temperatures
during midsummer |
|
Russetting
|
Ethylene exposure
during postharvest |
Disease
Management
| Anthracnose
| Botrytis gray mold | Bottom
rot | Damping-off |
| Downy mildew | Drop
| Nematode | Lettuce mosaic virus
|
| Cucumber mosaic virus | Broadbean
wilt virus | Astor yellows |
SARE Publication: "A Whole-Farm Approach to Managing Pests"
Anthracnose,
Microdochium panattonianum
|
Washington
State fact sheet on lettuce anthracnose
Time for concern: The fungus is favored by cool,
wet weather, which are normal conditions for the early-spring crop.
Key characteristics: Water-soaked, circular spots
first appear on the undersides of leaves. If bounded by large leaf veins,
these spots may be angular in shape. Later, the lesion centers dry up
and may fray or fall out giving a shot hole appearance. Lesions on the
midrib begin as water-soaked spots, but become markedly sunken. The fungus
survives in the soil and on crop debris. See
Reference 1.
| Management
Option |
Recommendation
|
| Scouting/thresholds |
Look
for spots on the outermost foliage and along the midrib on the lower
leaf surface. No thresholds have been established. |
| Resistant
varieties |
Anthracnose
affects most lettuce varieties, as well as escarole and endive.
Table of Boston/butterhead disease resistant varieties
Table of green leaf disease resistant varieties
Table of red leaf disease resistant varieties |
| Irrigation |
Wet
weather and irrigation are conducive for spore production and dispersal.Irrigation
at ground level is preferred to sprinklers. It is inadvisable to move
through the crop when the foliage is wet. |
| Crop
rotation |
Minimum
1 year rotation with a nonsusceptible crop. Crop rotation and disease management article
Cornell Forage Species Selection Tool |
| Seed selection/treatment |
Plant
disease-free seed. |
| Harvest |
Avoid
packing infected plants with healthy ones as deterioration and spread
can occur. |
| Postharvest |
The
fungus survives in the soil and on crop debris. Fields should be deep
plowed, and the debris should be inverted. Avoid packing infected
plants with healthy ones as deterioration and spread can occur. |
Site
selection and
Sanitation |
These
are not currently viable management options. |
|
Compound(s)
|
Comparing Environmental Risks of Pesticides
In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
|
Common name
Trade
Name |
Rate/A
Product |
PHI
(days) |
REI
(hours) |
Field
Use EIQ |
Comments |
|
azoxystrobin
(head, leaf and endive)
|
|
6.2-15.4 fl oz |
0 |
4 |
1-3 |
Do not apply more than 1 sequential application of these products or other strobilurin (Group 11) before alternating with a fungicide that has a different mode of action. Do not spray these products where spray drift may reach apple trees or use same sprayer to apply sprays to apple trees. |
|
2-5 oz |
0 |
4 |
2-4 |
| maneb (head, leaf and endive) |
|
1.5-2 lb |
5 |
24 |
24-32 |
Remove residues from head lettuce by stripping and trimming. |
|
1.2-1.6 qt |
5 |
24 |
19-25 |
| pyraclostrobin (head, leaf and endive) |
|
|
12-16
oz
|
0
|
12
|
|
Not for aerial application in NYS. Do not make more than 2 sequential applications before alternating to a fungicide with a different mode of action (other than group 11). |
|
Botrytis
gray mold, Botrytis cinerea
|
Picture
of lettuce gray mold
Penn
State lettuce disease fact sheet
Oregon
State gray mold ID fact sheet
Organic
management of GM on lettuce
Time for concern: Under humid conditions
in either greenhouse or plant bed locations
Key characteristics: Brownish to black
water-soaked lesions develop on leaf margins of outerleaves. Profuse
gray-brown conidia develop and may be followed with black resting bodies
(sclerotia). See Reference 1.
| Management
Option |
Recommendation
|
| Scouting/thresholds |
Record
the occurrence and severity of Botrytis gray mold. No thresholds have
been established. |
| Resistant
varieties |
No
resistant varieties are available. |
| Crop
rotation |
Rotation
is important to minimize crop residues and survival of sclerotia. Crop rotation and disease management article
Cornell Forage Species Selection Tool |
| Sanitation |
Strict
hygiene is essential in plant bed and greenhouse settings. |
Site
selection,
Seed selection/treatment,
and Postharvest |
These
are not currently viable management options. |
|
Compound(s)
|
Comparing Environmental Risks of Pesticides
In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
|
Common name
Trade
Name |
Rate/A
Product |
PHI
(days) |
REI
(hours) |
Field
Use EIQ |
Comments |
| boscalid (head and leaf lettuce) |
|
|
8-11
oz
|
14
|
12
|
15-21
|
For both head and leaf lettuce. Do not make more than 2 applications of Endura (Group 7) per crop per season. |
| cyprodinil + fludioxonil (head, leaf and endive) |
| Switch 62.5WG |
11-14 oz |
0 |
12 |
12 |
Begin at the onset of disease. After two applications of Switch 62.5WG, alternate to another fungicide with a different mode of action for two applications. |
| dicloran (head and leaf lettuce) |
|
|
2.66
lb
|
14
|
12
|
72
|
For
use on leaf lettuce only. |
|
Bottom
rot, Rhizoctonia solani
|
Picture
of bottom rot
Penn
State lettuce disease fact sheet
Organic
management of BR on lettuce
Time for concern: Under favorable
temperature and moisture conditions, this disease can appear as early
as four weeks after direct seeding or as advanced symptoms at heading.
Key characteristics: Bottom rot initially
appears as small, rust-colored spots on the underside of midribs in
direct contact with the soil. Wilting of outer wrapper leaves is often
the first symptom observed. Bottom rot may be confused with lettuce
drop and gray mold. See Reference
1.
| Management
Option |
Recommendation
|
| Scouting/thresholds |
Record
the occurrence and severity of bottom rot. No thresholds have been
established. |
| Resistant
varieties |
No
resistant varieties are available. |
| Crop
rotation |
Minimum
three year rotation away from lettuce and endive. Crop rotation and disease management article
Cornell cover crop decision tool
Cornell Forage Species Selection Tool |
| Raised
beds |
Planting
on raised beds will allow better air circulation and will reduce disease
incidence. |
|
Site selection,
Seed selection/treatment,
Postharvest, and
Sanitation
|
These
are not currently viable management options. |
|
Compound(s)
Common name
|
Comparing Environmental Risks of Pesticides
In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
|
Common name
Trade
Name |
Rate/A
Product |
PHI
(days) |
REI
(hours) |
Field
Use EIQ |
Comments |
azoxystrobin (head, leaf and endive) |
|
0.4-0.8 fl oz per 1,000 row feet |
0 |
4 |
<1 |
See warning about mixing Quadris and Amistar with certain insecticides and spray wetters. Do not spray these products where spray drift may reach apple trees or use same sprayer to apply sprays to apple trees.
. |
|
0.125-0.25 oz per 1,000 row feet |
0 |
4 |
1 |
| boscalid (head and leaf lettuce) |
|
8-11 oz |
14 |
12 |
15-21 |
For suppression of bottom rot of head and leaf lettuce. Do not make more than 2 applications of Endura (Group 7) per season |
| iprodione (head and leaf lettuce) |
|
|
1.5-2
lb
|
14
|
24
|
8-11
|
Thorough
coverage is essential for effective disease control. Apply 1 week
after transplanting or thinning and 10-20 days later if required. |
|
Damping-off,
Pythium spp.
|
UCONN
fact sheet on damping off
Time for concern: The disease is
most common when excessive moisture occurs, soils are poorly drained,
and the temperatures are unfavorable for seed germination and rapid
lettuce/endive growth.
Key characteristics: Disease can be expressed
as seed decay and pre- and postemergence damping-off of roots (hypocotyl)
and stems of young plants, leading to plant collapse and death. See
Reference 1.
| Management
Option |
Recommendation
|
| Scouting/thresholds |
Record
the occurrence and severity of damping-off. No thresholds have been
established. |
| Resistant
varieties |
No
resistant varieties are available. |
| Site
selection |
Avoid
compacted or poorly drained soils.
SARE Publication: "Building Soils for Better Crops"
SARE publication: "Managing Cover Crops Profitably"
Cornell cover crop decision tool |
| Seed selection/treatment |
Seed
treated with the appropriate fungicide for Pythiacious fungi may protect
seeds. |
Crop
rotation,
Postharvest, and
Sanitation |
These
are not currently viable management options. |
|
Compound(s)
|
Comparing Environmental Risks of Pesticides
In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
|
Common name
Trade
Name |
Rate/A
Product |
PHI
(days) |
REI
(hours) |
Field
Use EIQ |
Comments |
| mefenoxam (head, leaf and endive) |
|
|
1-2 pt
|
0
|
12
|
14-28
|
May be applied as a broadcast or banded application. See label for details. |
|
20-40 lb |
0 |
48 |
15-29 |
| propamocarb (head and leaf in field) (leaf lettuce inn greenhouse) |
|
2 pt
see label for GH use
|
21 |
12 |
|
For field application, Previcur Flex can be applied by directed nozzles to the lower portion of the plants and surrounding soil, via drip irrigation, in transplant/setting water, or by sprinklers. For greenhouse use, intended for treatment of rock wool cubes or soil or soilless seed beds only. |
|
|
Downy
mildew, Bremia lactucae
|
Penn
State lettuce disease fact sheet
Organic
management of DM on lettuce
Time for concern: Downy mildew
can be a major disease in field and greenhouse settings, and plants
are susceptible at all stages of plant growth.
Key characteristics: Young downy mildew
lesions are light green or chlorotic, and turn yellow or brown with
the onset of sporulation. Lesions are angular and delineated by large
veins. Sporangia (spores) appear primarily on the undersides of leaves.
See Reference 1.
|
Compound(s)
|
Comparing Environmental Risks of Pesticides
In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
|
Common name
Trade
Name |
Rate/A
Product |
PHI
(days) |
REI
(hours) |
Field
Use EIQ |
Comments |
azoxystrobin (head, leaf and endive) |
|
12.3-15.4 fl oz |
0 |
4 |
3 |
Do not apply more than 1 application of these products before alternating with a fungicide that has a different mode of action (other than Group 11). See comments below for maneb/mancozeb program. Do not spray these products where spray drift may reach apple trees or use same sprayer to apply sprays to apple trees
. |
|
4-5 oz |
0 |
4 |
3-4 |
|
dimethomorph (head and leaf lettuce)
|
|
|
6.4
oz
6.0 oz |
0
|
12
|
5
4
|
For head and leaf lettuce. Acrobat or Forum (Group 15) must be tank-mixed with appropriate protectant fungicide. Do not make more than 2 sequential applications before alternating to another effective fungicide with a different mode of action |
|
famoxadone
+cymoxanil (head lettuce only)
|
|
|
8
oz
|
3
|
12
|
5
|
For head lettuce. Tanos (Groups 11 + 27) must be tank-mix with appropriate protectant fungicide. Do not make more than 1 application before alternating with a fungicide with a different mode of action (other than Group 11). |
| fenamidone (head and leaf lettuce) |
|
5.5-8.2 fl oz |
2 |
12 |
3-4
|
Not for use or sale in Nassau or Suffolk Cos. For use on head and leaf lettuce. For optimal results, begin Reason (Group 11) applications as soon as environmental conditions become favorable for disease development. Do not make more than 1 application before alternating with a fungicide with a different mode of action. |
| fosetyl-Al (head, leaf and endive) |
|
|
2-5
lb
|
3
|
12
|
18-45
|
Remove
residues from head lettuce by stripping and trimming. |
| maneb (head, leaf and endive) |
|
1.5-2 lb |
5 |
24 |
24-32 |
Remove residues from head lettuce by stripping and trimming. |
|
1.2-1.6 qt |
5 |
24 |
19-25 |
| propamacarb (head and leaf lettuce) |
|
|
2pt, or 1.33 pt
|
2
|
12
|
29
|
Should be tank mixed with another fungicide registered
for downy mildew control and use a minimum of 1.33 pt/A. |
| pyraclostrobin (head, leaf and endive) |
|
|
16
oz
|
0
|
12
|
6
|
Not
for aerial application in NYS. Do
not make more than 2 applications before alternating to a fungicide
with a different mode of action. |
|
|
Drop,
Sclerotinia sclerotiorum, S. minor
|
Penn
State lettuce disease fact sheet
Organic
management of Drop on lettuce
Time for concern: The fungus is
favored by warm, wet conditions and is primarily noticed at or near
crop maturity.
Key characteristics: The fungus
attacks the outer leaves in contact with the soil, and wilting of these
leaves is the initial symptom. Infection progresses inwardly until the
entire plant wilts. Look for soft watery decay, snowy white mycelium,
and seed-size black sclerotia(mustard seed for S.M. or pea seed for
S.S.). See Reference 1.
| Management
Option |
Recommendation
|
| Scouting/thresholds |
Record
the occurrence and severity of drop. No thresholds have been established. |
| Resistant
varieties |
No
resistant varieties are available. |
| Crop
rotation |
Minimum
three year rotation with nonhosts such as grains is helpful where
practical. Crop rotation and disease management article
Cornell cover crop decision tool
Cornell Forage Species Selection Tool |
Site
selection,
Seed selection/treatment,
Postharvest, and
Sanitation |
These
are not currently viable management options. |
|
Compound(s)
|
Comparing Environmental Risks of Pesticides
In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
|
Common name
Trade
Name |
Rate/A
Product |
PHI
(days) |
REI
(hours) |
Field
Use EIQ |
Comments |
| boscalid (head and leaf lettuce) |
|
|
8-11
oz
|
14
|
12
|
15-21
|
For head and leaf lettuce. Do not make more than 2 applications of Endura (Group 7) per season. |
| Coniothyrium
minitans (head, leaf and endive) |
|
Contans
WG
|
2-4
lb/
50-100 gal water
|
0
|
4
|
NA
|
This
biological fungicide has been tested in some states; however, limited
information is available on effectiveness in our region. Apply 3
to 4 months prior to the onset of disease to allow the active agent
to reduce inoculum levels of sclerotia in soil. following application,
incorporate to a depth of 1 to2 inches but do not plow before
seeding lettuce to avoid untreated sclerotia in lower soil layers
from infesting the upper soil level.
|
| cyprodinil + fludioxonil (head, leaf and endive) |
| Switch 62.5WG |
11-14 oz |
0 |
12 |
12 |
Make first application at thinning and again two weeks later. |
| dicloran (head and leaf lettuce) |
|
|
2-3.33 lb
3 1/3-5 1/3 lb
2 2/3 lb
|
14
|
12
|
54-90
|
Apply 2 lb as preemergence in 20-50 gal water in a 4-6in band over transplant or seed row. Make a second application of 3 1/3 lb in 50-100 gal water immediately after thinning.
Use this rate for a single application immediately after thinning in 50-100 gal water.
Use this rate prior to thinning and repeat immediately after thinning. Use a sprayer with drop nozzles to direct the spray in 50-100 gal water to the lower portion of plants and surrounding soil. |
| iprodione (head and leaf lettuce) |
|
|
1.5-2
lb
|
14
|
24
|
8-11
|
Up
to 3 applications may be made. Thorough coverage is essential for
effective disease control. Do not disturb the soil after treatment.
|
|
|
See Cornell
fact sheet on RKN
Time for concern: Seedling through
harvest but control measures are only effective before or at planting
Key characteristics: Observing
root galls (spherical or beadlike) is the best way to detect root-knot
nematodes in the field. Severely infected plants are stunted and exhibit
wilting in midday, especially during hot and
sunny days.
|
Compound(s)
|
Comparing Environmental Risks of Pesticides
In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
|
Common name
Trade
Name |
Rate/A
Product |
PHI
(days) |
REI
(hours) |
Field
Use EIQ |
Comments |
| metam
sodium |
|
|
25
gal
|
0
|
|
NA
|
Rate
given is for muck soil. To achieve successful control, follow label
recommendations as to soil preparation, depth of injection, soil temperature,
and moisture. |
Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)
Penn
State lettuce disease fact sheet
Time for concern: Entire season,
from seeding to production of overlapping plantings
Key characteristics: The seedborne
"mother" plants show early mosaic symptoms, stunting, and lack
of development. Secondary infected plants show mosaic, leaf puckering,
and deep or accentuated serration of the leaf margins. Endive heads may
be stunted, but generally only show mild symptoms. See
References 1 and 2.
See Cornell
fact sheet on CMV
Penn
State lettuce disease fact sheet
Time for concern: Early aphid flights (May through
June) carry inoculum into the susceptible crop, and subsequent spread
may occur during the course of the season.
Key characteristics: This mosaic is more
intense than LMV. Veinal browning and necrosis occurs when temperatures
are in the mid-50's or lower. See
References 1 and 2.
| Management
Option |
Recommendation
|
| Scouting/thresholds |
Record
the occurrence and severity of CMV. No thresholds have been established.
|
| Resistant
varieties |
No
resistant varieties are available. |
| Site
selection |
Make
the earliest planting downwind from weedy border areas, so that older
lettuce plantings do not serve as reservoirs of virus for subsequently
planted crops. See | |