Chapter 19 Lettuce and Endive
Contents
19.5.1 Anthracnose, Microdochium panattonianum
19.5.2 Botrytis gray mold, Botrytis cinerea
19.5.3 Bottom rot, Rhizoctonia solani
19.5.4 Damping-off, Pythium spp
19.5.5 Downy mildew, Bremia lactucae
19.5.6 Drop, Sclerotinia sclerotiorum, S. minor
19.5.7 Northern root-knot nematode,
Meloidogyne hapla
19.5.8 Lettuce mosaic virus (LMV)
transmitted by aphids
19.5.9 Cucumber mosaic virus (CMV)
transmitted by aphids
19.5.10 Broadbean wilt virus (BBWV)
transmitted by aphids
19.5.11 Aster yellows (AY)
phytoplasma transmitted by aster leafhoppers
19.6.2 Aphids, primarily the green
peach aphid, Myzus persicae
19.1
Recommended Varieties
Table 19.1.1 Recommended lettuce and endive varieties.
|
LETTUCE |
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|
Butterhead (Boston) |
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Romaine (Cos) |
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Ermosa (48)1 |
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Dark Green Cos (70) |
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Nancy (52) |
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Green Towers (70) |
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Buttercrunch (60) |
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Ideal Cos (75) |
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Summer Bibb (65) |
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Parris Island Cos (76) |
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Tania (65) |
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Esmerelda (68) |
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Dark Green Boston (75) |
|
Leaf |
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Grand Rapids (45) |
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Crisphead (Iceberg) |
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Red Sails (45) |
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Great Lakes |
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Tierra (46) |
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Ithaca |
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New Red Fire (48) |
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Onondaga |
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Sierra (red, 50) |
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Raleigh |
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Slobolt (50) |
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South Bay |
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Waldmann’s Green (50) |
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ENDIVE |
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Florida Deep Heart |
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Green Curled Ruffle |
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Full Heart Batavia |
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Salad King |
1Approximate days to harvest
19.2
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.
19.3
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 19.3.1 for the recommended rates of nitrogen, phosphorus,
and potassium.
19.4
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.
|
Table 19.3.1 Recommended nutrients based on soil tests. |
||||||||
|
N pounds/acre |
P2O5
pounds/acre |
|
K2O pounds/acre |
Comments |
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Soil Phosphorus
Level |
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Soil Potassium
Level |
|
||||
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|
low |
med. |
high |
|
low |
med. |
high |
|
|
100 (50-100 on muck) |
120 |
80 |
40 |
|
150 |
100 |
50 |
Total recommended |
|
40 |
90 |
50 |
0 |
|
120 |
70 |
50 |
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 soils. |
Table 19.4.1 Nonpathogenic disorders
|
Disorder |
Cause |
|
Tipburn |
Poor water management/calcium deficiency. Plant tipurn resistant varieties during warmer parts of growing season. |
|
Poor stand |
Thermodormancy due to soil temperatures >80F. Irrigate when seeding in hot weather. |
|
Bolting |
High night temperatures during early summer |
|
Russetting |
Ethylene exposure during postharvest |
19.5
Disease Management
19.5.1 Anthracnose, Microdochium
panattonianum
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. |
|
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|
Resistant varieties |
Anthracnose affects most lettuce varieties, as well as
escarole and endive. |
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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. |
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Crop rotation |
Minimum 1 year rotation with a nonsusceptible crop. |
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Seed selection/treatment |
Plant disease-free seed. |
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Harvest |
Avoid packing infected plants with healthy ones as
deterioration and spread can occur. |
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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. |
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Site selection and
Sanitation |
These are not currently viable management options. |
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Compound(s) |
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Common name |
Rate/A |
PHI |
REI |
Field |
|
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Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
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|
azoxystrobin |
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|
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|
Quadris
F |
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. |
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|
|
Amistar
80 WDG |
2-5 oz |
0 |
4 |
2-4 |
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pyraclostrobin |
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|
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Cabrio
EG |
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). |
||
19.5.2 Botrytis gray mold, Botrytis
cinerea
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. |
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Resistant varieties |
No resistant varieties are available. |
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Crop rotation |
Rotation is important to minimize crop residues and
survival of sclerotia. |
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Sanitation |
Strict hygiene is essential in plant bed and greenhouse
settings. |
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Site selection, Seed
selection/treatment, and Postharvest |
These are not currently viable management options. |
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Compound(s) |
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Common name |
Rate/A |
PHI |
REI |
Field |
|
|||
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|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
boscalid |
|
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|
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Endura
DF |
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. |
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dicloran |
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Botran
75-W 0.75 lb/lb |
2.66 lb |
14 |
12 |
72 |
For use on leaf lettuce only. |
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19.5.3 Bottom rot, Rhizoctonia
solani
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. |
|
Raised beds |
Planting on raised beds will allow better air circulation and
will reduce disease incidence. |
|
Site selection, Seed
selection/treatment, Post-harvest, and Sanitation |
These are not currently viable management options. |
|
Compound(s) |
|
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|
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|
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|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
|
azoxystrobin |
|
|
|
|
||
|
|
Quadris
F |
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. |
|
|
Amistar
80 WDG |
0.125-0.25 oz per 1,000 row feet |
0 |
4 |
1 |
|
|
boscalid |
|
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Endura
DF |
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 |
|
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|
|
|
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Rovral
50W 0.5 lb/lb |
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. |
19.5.4 Damping-off, Pythium
spp
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. |
|
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|
Resistant varieties |
No resistant varieties are available. |
|
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|
Site selection |
Avoid compacted or poorly drained soils. |
|
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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) |
Rate/A |
PHI |
REI |
Field |
|
|||
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
mefenoxam |
|
|
|
|
|
|||
|
|
Ridomil
Gold EC or OLF |
1-2 pt |
21 |
48 |
14-28 |
May be applied as a broadcast or banded application. |
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|
Ridomil
Gold GR |
20-40 lb |
0 |
48 |
15-29 |
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propamocarb |
|
|
|
|
|
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|
*Previcur
Flex |
see
label |
2 |
12 |
|
For
greenhouse use only on leaf lettuce for prevention of root rot and
damping-off caused by Pythium spp.
and Phytophthora spp. |
||
19.5.5 Downy mildew, Bremia
lactucae
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.
|
Management
Option |
Recommendation |
|
||||||
|
Scouting/thresholds |
Spray every seven to ten days when disease appears. |
|
||||||
|
Resistant varieties |
Breeding resistant varieties is a continuing task since
the fungus readily produces new races. |
|
||||||
|
Fungicide use |
Because of the high variability of fungus, insensitivity
to the systemic fungicide metalaxyl
(mefenoxam) is widespread. |
|
||||||
|
Crop rotation, Site
selection, Seed selection/ treatment, Postharvest, and Sanitation |
These are not currently viable management options. |
|
||||||
|
Compound(s) |
|
|
|
|
|
|||
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|||
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
azoxystrobin |
|
|
|
|
||||
|
|
Quadris
F |
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. |
||
|
|
Amistar
80 WDG |
4-5 oz |
0 |
4 |
3-4 |
|||
|
dimethomorph |
|
|
|
|
|
|||
|
|
Acrobat
50 WP, Forum SC |
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 |
|
|
|
|
|
|||
|
|
Tanos
50 DF |
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 |
|
|
|
|
|
|||
|
|
*†Reason
500 SC |
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 |
|
|
|
|
|
|||
|
|
Aliette
WDG 0.8 lb/lb |
2-5 lb |
3 |
12 |
18-45 |
Remove residues from head lettuce by stripping and
trimming. |
||
|
Compound(s) |
|
|
|
|
|
|
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
|
maneb |
|
|
|
|
|
|
|
|
Maneb
75 DF 0.75 lb/lb |
1.5-2 lb |
10 |
24 |
24-32 |
Remove residues from head lettuce by stripping and
trimming. |
|
|
Manex 4 lb/gal |
1.2-1.6 qt |
10 |
24 |
19-25 |
|
|
propamocarb |
|
|
|
|
|
|
|
|
*Previcur
Flex |
2 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 |
|
|
|
|
|
|
|
|
Cabrio
EG |
16 oz |
0 |
12 |
6 |
Not for aerial application in NYS.
For head and leaf lettuce. Do not make more than 2 sequential applications
of Cabrio (Group 11) before alternating to a fungicide with a different mode
of action. |
|
*Restricted
use. |
|
|
|
|
|
|
19.5.6 Drop, Sclerotinia
sclerotiorum, S. minor
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. |
|
||||||
|
Site selection, Seed
selection/treatment, Postharvest, & Sanitation |
These are not currently viable management options. |
|
||||||
|
Compound(s) |
|
|
|
|
|
|||
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|||
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
boscalid |
|
|
|
|
|
|||
|
|
Endura
DF |
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 |
|
|
|
|
|
|||
|
|
Contans
WG |
2-4 lb/ 50-100 gal water |
0 |
4 |
|
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 to 2 inches but do not plow before seeding lettuce
crops to avoid untreated sclerotia in lower soil layers from infesting the
upper soil level. |
||
|
Compound(s) |
|
|
|
|
|
|
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
|
dicloran |
|
|
|
|
|
|
|
|
Botran
75 W 0.75 lb/lb |
2-3.33 lb |
14 |
12 |
54-90 |
|
|
|
|
|
|
|
|
|
|
iprodione |
|
|
|
|
|
|
|
|
Rovral
50W 0.5 lb/lb |
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. |
19.5.7 Northern root-knot nematode, Meloidogyne
hapla
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.
|
Management
Option |
Recommendation |
|
||||||
|
Scouting/thresholds |
Record the occurrence and severity of root-knot nematode
infection on roots. Damage threshold
to lettuce is 2 eggs/cc of organic soil. |
|
||||||
|
Resistant varieties |
No resistant varieties are available. |
|
||||||
|
Crop rotation |
Rotate with a grain crop to reduce nematode density and
damage. Green manure of Trudan 8, a
Sudan grass hybrid has been found effective against this nematode, as well as
selections of white clover and flax.
Crucifer green manures are also effective. |
|
||||||
|
Postharvest |
Fumigation in the fall when soil temperatures are still
warm is effective in controlling this nematode. |
|
||||||
|
Site selection, Seed selection/treatment,
and Sanitation |
These are not currently viable management options. |
|
||||||
|
Compound(s) |
|
|
|
|
|
|||
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|||
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
metam sodium |
|
|
|
|
|
|||
|
|
Vapam
HL |
25 gal |
0 |
|
|
Rate given is for muck soil. To achieve successful
control, follow label recommendations as to soil preparation, depth of
injection, soil temperature, and moisture. |
||
19.5.8 Lettuce mosaic virus (LMV) transmitted by aphids
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.
|
Management
Option |
Recommendation |
|
Scouting/thresholds |
Record the occurrence and severity of LMV. No thresholds
are available. |
|
Resistant varieties |
Plant resistant varieties. See Section 20.1 Recommended
Varieties. |
|
Seed selection/treatment |
LMV is seedborne in all lettuce types, but not in endive.
Purchase lettuce seed designated mosaic tolerance zero (MTO) or zero infected
seeds in 30,000. |
|
Crop rotation, Site
selection, Seed selection/ treatment, Postharvest, and Sanitation |
These are not currently viable management options. |
|
Compound(s) |
No pesticides are available to manage LMV. |
19.5.9 Cucumber mosaic virus (CMV) transmitted by aphids
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. |
|
Sanitation |
Eliminate weed hosts. Perennial weed sources for CMV include
common milkweed, marshcress, and yellow rocket. |
|
Crop rotation, Seed
selection/treatment, and Postharvest |
These are not currently viable management options. |
|
Compound(s) |
No pesticides are available to manage CMV. |
19.5.10 Broadbean wilt virus (BBWV) transmitted by aphids
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: Symptoms are similar to those of LMV and CMV,
but with low field temperatures, the infected plants develop severe veinal
necrosis. See
References 1 and 2.
|
Management
Option |
Recommendation |
|
Scouting/thresholds |
Record
the occurrence and severity of BBWV. No thresholds are available. |
|
Resistant varieties |
Some
varieties are highly susceptible. Check with your local extension agent for a
list of susceptible varieties. |
|
Sanitation |
Eliminate weed hosts. Weed sources for BBWV are broadleaf
plantain and buckhorn plantain, both of which are perennials. |
|
Crop rotation, Site
selection, Seed selection/treatment, and Postharvest |
These are not currently viable management options. |
|
Compound(s) |
No pesticides are available to manage BBWV. |
19.5.11 Aster yellows (AY) phytoplasma transmitted by aster leafhoppers
Time for concern: June through September; the occurrence of AY follows
the migration pattern of leafhoppers. Leafhoppers can remain infectious for 100
days.
Key characteristics: The disease results in strikingly yellowed
and stunted plants, which are unmarketable. See Reference 1.
|
Management
Option |
Recommendation |
|
Scouting/thresholds |
Record the occurrence and severity of aster yellows. No
thresholds have been established. |
|
Resistant varieties |
No resistant varieties are available. |
|
Crop rotation, Site
selection, Seed selection/ treatment, Postharvest, & Sanitation |
These are not currently viable management options. |
|
Compound(s) |
Management of AY depends on reducing the aster leafhopper
population which migrates into lettuce fields about mid-June. |
19.6
Insect Management
19.6.1 Aster leafhopper, Macrosteles
quadrilineatus, transmits the pathogen for aster yellows disease
Time for concern: Mid-June through the end of the growing
season
Key characteristics: This insect overwinters on wild and cultivated grasses.
|
Management
Option |
Recommendation |
|
||||||
|
Scouting/thresholds |
Begin treatment when the lettuce is 1/2 inch high or when
the first leafhoppers are observed. |
|
||||||
|
Resistant varieties |
No resistant varieties are available. |
|
||||||
|
Crop rotation |
Crop rotation is ineffective due to the leafhopper's
migratory capabilities. |
|
||||||
|
Postharvest |
Destroy all lettuce plants in the field immediately after
harvest. |
|
||||||
|
Sanitation |
Where possible, mow headlands around fields. |
|
||||||
|
Site selection, Seed
selection/treatment, and Natural enemies |
These
are not currently viable management options. |
|
||||||
|
Compound(s) |
|
|
|
|
|
|||
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|||
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
acephate |
|
|
|
|
||||
|
|
Orthene
97 0.97 lb/lb |
0.5-1.0 lb |
21 |
24 |
11-23 |
For crisphead lettuce only. Four or 5 applications at 7
day intervals are usually necessary. Apply in low gallonage sprays (35-40 gal/A). |
||
|
cypermethrin |
|
|
|
|
||||
|
|
*Ammo
2.5 EC 2.5 lb/gal |
2.5-5 fl oz |
5 |
12 |
1-3 |
For crisphead lettuce only. Four or 5 applications at 7
day intervals are usually necessary. Apply in low gallonage sprays (35-40
gal/A). |
||
|
dimethoate |
|
|
|
|
||||
|
|
Dimethoate
400 4 lb/gal |
0.5 pt |
14 |
48 |
16 |
Provides only fair control. |
||
|
Compound(s) |
|
|
|
|
|
|
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
|
disulfoton |
|
|
|
|
|
|
|
|
*Di-Syston
8 8 lb/gal |
1-2 pt /1000 ft of row @ 20-inch
spacing |
60 |
48 |
|
|
|
imidacloprid |
|
|
|
|
|
|
|
|
*Admire
Pro 4.6 lbs/gal |
4.4-10.5 fl oz |
21 |
12 |
4-10 |
|
|
lambda-cyhalothrin |
|
|
|
|
|
|
|
|
*Warrior 1 lb/gal |
2.56-3.84 fl oz |
1 |
24 |
<1-1 |
|
|
methomyl |
|
|
|
|
|
|
|
|
*Lannate
LV 2.4 lb/gal |
1-1.67 pt |
7 to 10 |
48 |
10-15 |
PHI
is 7 days for rates up to 1.5 pt; PHI
is 10 days for rates above 1.5 pt. |
|
zeta-cypermethrin |
|
|
|
|
|
|
|
|
*Mustang
MAX 0.8 lb/gal |
2.24-4.0 fl oz |
5 |
12 |
<1 |
Head lettuce only |
|
*Restricted
use only. |
|
|
|
|
||
19.6.2 Aphids, primarily the green peach aphid, Myzus persicae
Time for concern: Mid-July through the end of the growing
season
Key characteristics: Green peach adult aphids can be green, pink,
red, or dark brown. They range in length from 1/32 to 1/16 inch. Aphids may
buildup on plants and transmit viruses.
|
Management
Option |
Recommendation |
|
||||||
|
Scouting/thresholds |
Record the occurrence and severity of an aphid infestation.
No thresholds have been established. |
|
||||||
|
Natural enemies |
Natural enemies help control aphid populations. They can
be preserved using pesticides that are less harmful to them. Use Reference 3 or
www.nysaes.cornell.edu/ent/biocontrol/ for identification of natural enemies. |
|
||||||
|
Note(s) |
New York State lettuce entering the export market must be
kept clean of aphids through the use of aphicides. Even the best aphicide will
not reduce the spread of mosaic viruses transmitted by aphids from sources
outside of the field. |
|
||||||
|
Resistant varieties |
No resistant varieties are available. |
|
||||||
|
Postharvest |
Destroy all lettuce plants in the field immediately after
harvest. |
|
||||||
|
Crop rotation, Site
selection, and Sanitation |
These are not currently viable management options. |
|
||||||
|
Compound(s) |
|
|
|
|
|
|||
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|||
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
acephate |
|
|
|
|
||||
|
|
Orthene
97 0.97 lb/lb |
0.5-1.0 lb |
21 |
24 |
11-23 |
For use on crisphead lettuce only. Do not apply after the first
head begins to form. Do not feed trimmings to livestock or allow animals to
graze on treated areas. |
||
|
acetamiprid |
|
|
|
|
|
|||
|
|
Assail
30SG 0.3 lb/lb |
2.0-4.0 oz |
7 |
12 |
1-2 |
|
||
|
Compound(s) |
|
|
|
|
|
|||
|
Common name |
Rate/A |
PHI |
REI |
Field |
|
|||
|
|
Trade
name |
Product |
(days) |
(hours) |
Use EIQ |
Comments |
||
|
dimethoate |
|
|
|
|
||||
|
|
Dimethoate
400 4
lb/gal |
0.5 pt |
14 |
48 |
16 |
Provides only fair control. |
||
|
disulfoton |
|
|
|
|
|
|||
|
|
*Di-Syston
8 8 lb/gal |
1-2 pt/1000 ft. of row @ 20-inch
spacing |
60 |
48 |
|
|
||
|
imidacloprid |
|
|
|
|
||||
|
|
*Admire
Pro 4.6 lbs/gal |
4.4-10.5 fl oz |
21 |
12 |
4-10 |
|
||
|
|
*Provado
1.6F 1.6 lb/gal |
3.75 fl oz |
7 |
12 |
2 |
Do not apply >18.75 fl oz per year. |
||
|
methomyl |
|
|
|
|
|
|||
|
|
*Lannate
LV 2.4 lb/gal |
1-1.67 pt |
7 to 10 |
48 |
10-15 |
PHI
is 7 days for rates up to 1.5 pt; PHI is
10 days for rates above 1.5 pt. |
||
|
oxydemeton-methyl |
|
|
|
|
||||
|
|
*MSR 2 lb/gal |
1 qt |
21 |
48 |
38 |
For use on crisphead lettuce only. Not more than 3
applications per season. |
||
|
pymetrozine |
|
|
|
|
||||
|
|
Fulfill 0.5lb/lb |
2.75 oz |
7 |
12 |
24 |
Apply when aphids first appear but before populations
build to damaging levels. Do not
exceed 5.5 oz/A per season. Allow 7
days between applications. |
||
|
*Restricted
use only. |
|
|
|
|
||||
19.6.3 Slugs
Time of concern: Early spring and fall
Key characteristics: Adult slugs are between one and two inches in length. Slugs can overwinter at any stage of development. Although slugs cannot survive prolonged subzero temperatures or desiccation, the burrows of small mammals and worms provide insulation. Slugs begin to move, hatch, feed, and lay eggs in the spring when temperatures are consistently above 40°F. There is often little or no slug activity in the field during periods of dry weather; however, there may be extensive feeding in damp areas.
|
Management
Option |
Recommendation |
|
||||||
|
Scouting/thresholds |
Record the occurrence and severity of slug damage. No thresholds
have been established. |
|
||||||
|
Resistant varieties |
No resistant varieties are available. |
|
||||||
|
Site selection/planting,
Crop rotation, Post-harvest, and Sanitation |
Practices that help dry the soil surface (e.g. conventional
tillage and good weed control) will reduce slug populations. |
| ||||||