Insect control on vegetables

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Title: Insect control on vegetables

1
Insect control on vegetables

Jeffrey Wyman
Department of Entomology

2
Vegetable Production in Wisconsin

Important production state nationally
Good crop climate also limits pests
Production linked historically to canning
industry
Recent increase in fresh market

3
Wisconsin Vegetable Production Statistics (Wis.
Ag. Stats. 2002)
??Perspective Corn?3.3 million acres 1.0
billion, Soybeans?1.5 million acres 240 million
4
Insect Management on Vegetables

The problem
Many Insects on Many Crops
Some perspective on insects
Why is it difficult to manage insects?
Lots of insect species on the planet
Over 1 million animal species
¾ are arthropods
Remember only a few are actually pests
Each species has lots of individuals
Short life cycles
High numbers of individuals
Combination HIGH REPRODUCTIVE CAPABILITY

5
Insect Reproductive Potential

Example Fruit flies
2 week life cycle 25 generations per year
100 eggs per female
If 1 pair mate and all offspring survive for 1
year 1041 flies!!
If packed 1000 flies/cubic inch ball of flies
96 million miles in diameter ½ the distance to
the sun!
So,why have the insects not taken over?

6
Factors that regulate insect populations

Physical Factors
Environment
Temperature, rainfall
Pesticides
Biological Factors
?Influence increases at higher populations?
Competition
Food availability
Parasites, predators
disease

Insect management seeks to blend various
biological and physical factors together to hold
pests at acceptable levels.
7
Insect Management ? The 6-step Process

Identify the key pests
Look closely at
Biology
Ecology
Behavior
Impact on crop
Identify weak links
Develop management strategies to exploit
weaknesses
Tailor IPM to individual needs
Fit sporadic pests into program

8
Insect Management Trends on Vegetables

1950s to 1980s

High value Low tolerance HIGH RELIANCE ON
INSECTICIDES
9
Insect Management Trends on Vegetables

1980s to 1990s Problems

Fewer insecticides
Resistance in pests
Label cancellations
Reregistration
FQPA
Raw product residues
Worker safety
Environmental concerns
Nontarget toxicity
Groundwater

10
Insect Management Trends on Vegetables
Targeted insecticide use
Integration of non-chemical alternatives
Present and Future
Reduced risk, ecologically-based IPM
11
Insect Management Trends on Vegetables

Use 3 crops, potatoes, cole crops and snap beans,
to illustrate major trends in IPM for commercial
crops and explore linkages to smaller scale IPM
Examine insect pests, damage and approaches to
control in a range of other commonly grown crops
Sweet corn, peppers, tomatoes
Cucurbits, carrots

Potato Production in Wisconsin
85,000 Acres, value 203 million, 3rd Nationally
Most grown in Central Wisconsin

13
Potato Pest Management

IPM Success story
Many damaging pests Heavy pesticide
reliance
Major problems
Environmental groundwater, drift
Resistance to pesticides potato beetle
Industry partnership with University and World
Wildlife fund to reduce pesticide reliance
New standards developed with independently
certified eco-label
Healthy Grown label launched in 2001

14
Insect Management in Potatoes - Key Pests -
Green peach aphid
Colorado potato beetle
Potato leafhopper
15
Colorado potato beetle adult
16

Overwintering site
Close to last crop
Adults 6 to 12 deep
Protected by mulch

Adults walk to crop
Damage depends on temperature
May - June

Adults lay eggs on underside of leaves
Yellow / orange
20-40 eggs/mass

Larvae hatch 5-7 days
1st instar move to plant terminals
Little damage

Small larvae feed in terminals
4 instars, 5-7 days/stage
Large larvae (34) feed extensively

4th instar larva

Larval feeding
4th instars leave plant and pupate
in soil

Pupae in soil
2-3 weeks
Summer adults emerge (July)

Summer adults emerge in July
Very active
Very hungry

Rapid defoliation
Partial second generation
Adults leave to overwinter or
Can be partial 3rd gen.

Management on crop
Prediction
Timing
Resistance

Infesting crop
Trap crops
Trenches
Physical control

Jul
Jun
Aug
May
Colorado potato beetle ecology
Sep

Leaving crop
Trap crops
Physical control

Finding crop
Crop rotation
Cover crops
Disrupt dispersal

Apr
Oct
Mar
Nov
Feb
Dec
Jan

Adult diapause
Habitat disruption
Cold shock

27
Managing outside crop

Rotate crop to avoid adults
Trap adults moving into crop in spring
Trap adults moving out of crop in fall
Freeze adults in winter??

28
Rotate crop to avoid adults
29
Trap adults moving into crop
30
Trenching
31
Insecticide on edge to trap adults
32
Propane flaming
33
Bug Vacuum
34

Management on the crop
May September

35
Biological Controls

Predators, parasites exist but rarely effective

36
Physical Control

Prevent adults reaching plants
Row cover May-June
Hand pick adults, eggs
May early June
Freeze adults in winter??

37
Chemical Control

Must control overwintered generation in June
Ignore overwintered adults unless severe feeding
Target young larvae, 1st and 2nd instar
Look for egg hatch
5 to 10 days, depending on temperature
250 heat units from 1st eggs

38
Chemical Control
Problem beetle has developed resistance
to many insecticides e.g. carbaryl
Tools available Biological (specific)

Bacillus thuringiensis var tenebrionis
Target 1st, 2nd instar
Multiple applications
Good coverage needed
Spinosad (conserve)
Target 1st, 2nd generations
1-2 applications only

39
Chemical Control (cont.)
Synthetic (general insect control)

Pyrethroids
Cyfluthrin, esfenvalerate, permethtin
Check fact sheet x 1097 for trade names
1-2 applications
Will kill natural controls also
May be resistance

40
Potato Leafhopper

Appearance
Adults, small (1/8) wedgeshaped, bright green
Rapid movement
Nymphs, yellow-green, lack wings
Occurrence
Do not overwinter in Wisconsin
Adults migrate from gulf states
Arrive June, 2-3 generations/year
Very broad host range
includes potatoes, beans, alfalfa
Can infest very quickly

41
Potato Leafhopper - damage

Both adults and nymphs feed
Sucking mouthparts
Saliva clogs conductive tissue and
Causes yellowing leaf curl and
necrosis hopperburn
Stunting can also occur

42
Potato Leafhopper - damage
43
Potato Leafhopper Control

Cultural
Row cover (June, July)
Early plant/early harvest
Biological
No effective controls
Chemical
Monitor regularly
Treat at 1 adult/sweep net
Do not let nymphs build up
Control is effective
Carbaryl
Pyrethroids (see x1097)
Insecticidal soap

44
Aphids on potatoes
Key pests on seed potatoes only
Green-peach aphid Potato aphid Winged
aphids
45
Green peach aphid

Very wide host range (300)
Very prolific
Asexual, live young, 14 day generations
Overwinter on Prunus sp. and in south
Winged forms infest crop in June/July
Followed by multiple wingless generations
Direct damage only if very high pops

46
Potato aphid

Potatoes, tomatoes
Very prolific
Overwinter on rose
Infest potato in June/July (plant terminals)
Rarely cause serious damage

47
Aphid damage and control on seed potatoes

Aphids are primary virus vectors on potato
Green peach is the most efficient vector
Key pests in certified seed production
Intense chemical control
Low thresholds (1 aphid/10 leaves)

48
Aphid damage on fresh market or garden potatoes

Always use new certified seed (low virus)
Current season virus not a concern,BUT, do
not save seed or virus will cause severe yield
reduction in second year
Aphid control only necessary to control high
populations in late season
Allow biological control to regulate populations
(parasites and predators)

49
Biological control of aphids

Usually effective
Avoid disruption

Predators
Parasitoids
50
Sporadic pests of potato
Potato flea beetle
European corn borer
Cut worms
White grub
Wire worm
51
Flea beetle

Overwinter as adult
2 generations/year
Adults in May and July
Small holes in leaf (shothole)
Larvae feed in soil
Rarely damaging

52
Flea beetle control

Usually not needed
Cultural
Row cover
Biological
Not effective
Chemical
Not usually needed
Carbaryl, pyrethroids

53
Lepidopterous larvae (worms)

Black cutworm, variegated cutworm
Various loopers
Adults are night flying moths
Larvae feed on leaves (July-Aug)
Sample by shaking from plants.
counting in/on soil
Threshold 4-8 larvae/plant

54
Worm control

Usually not needed
Cultural
Remove weeds/debris
Biological
Parasitoids and predators
Chemical
Treat at thresholds
Btk
Pyrethroids

55
European corn borer

Overwinter in corn
2 generations/year, 1st gen. can damage potatoes
Larvae bore into stems in June
Limited damage
Norkotah, Norgold are susceptible

56
Corn borer control on potato

Cultural
Avoid Norgold, Norkotah
Do not plant close to sweet corn
Biological
Not effective
Chemical
Treat 7-10 days after 1st adult peak flight if
eggs found on 15 of leaves
Pyrethroids

57
Tuber damaging insects

White grub (June beetle)
2-3 year life cycle
Adults lay eggs in grass
Larvae feed on tubers 2-3 years
Wireworm (click beetle)
4-6 year life cycle
Adults lay eggs on grass
Larvae feed 3-5 years on tubers

58
Soil insect control

Cultural
Do not plant potatoes after sod/grass
Control grass weeds
Biological
None effective
Chemical
None available

59
Potato insect management -Summary
Pesticide reliant crop where biology and ecology
of pests is used to reduce insecticide use and
toxicity

Colorado potato beetle
Manage outside crop with rotation,
trap crops, climate
Manage on crop with prediction and
timing
Potato leafhopper
Manage with thresholds
Sporadic pests
Aphids Parasites, predators
Lepidoptera Biological insecticides/thresholds
Flea beetles Do not control
Tuber pests Clean culture

60
Cole Crop Insect Control
Many crops with same insect pest complex
Head crops
Cabbage
Cauliflower
Broccoli
Also Brussels sprouts, Kale, Kohlrabi, Collards,
Mustard greens, Chinese cabbage, etc.
Root crops Turnips, Radish, Rutabaga, etc.
61
Insect Pest Complex
Key Pests - Lepidoptera
Diamond back moth
Imported cabbage worm
Cabbage looper
Sporadic Pests
Cabbage maggot
Flea beetle
Cabbage aphid
62
Managing Insects on Cole Crops

??Excellent example of potential for biological
control ??
(Mahr et. al. NCR Regional pub. 471)
History of problem
Direct damage to marketable product by key pests
Worms on heads
Maggots on roots
Multiple insecticide applications used
Resistance developed as threat to production
Solution
IPM implementation based on biological control of
key pests
Pesticides switched to specific, soft materials
to preserve natural control

63
Key Pests of Cole Crops

Complex of 3 lepidopteran species
All feed on marketed crop
Need to identify species but can treat as a
complex

Imported cabbage worm
Cabbage looper
Diamondback moth
64
Diamondback moth life cycle

Adult
Small night flyer, short fast flights
½, wings have diamond pattern
Can monitor with pheromone trap
Eggs
Small, hard to see
Laid close to veins
Larvae
4-5 instars up to ¾ long
2-3 weeks
Cigar shaped, pointed at ends
wiggle when touched
Spin thread and hang
Pupa
Usually on underside of leaves
Neatly spun pupal case

65
Diamondback moth

Occurrence
Does not overwinter in Wisconsin
Blown in on wind or imported on plants
4-8 generations per year
Damage
Window pane feeding, may also deform heads
1st instar mine in leaf
Damage usually early-mid season (June/July)
Resistance to many insecticides
Major problem worldwide

66
Imported Cabbage Worm life cycle

Adult
White, day flying butterfly
Eggs
Laid single on undersurface
White, turning yellow at hatch
Cigar shaped
Larvae
5 instars 3-4 weeks
Velvety green with yellow dorsal line
Slow moving
Up to 1 ½ inches in length
Pupa
Distinctive angular shape
Usually on plant debris/old leaves

67
Imported Cabbage Worm

Occurrence
Overwinters as pupae in Wisconsin
3 generations per year, 1st on weeds
Damage
Usually most damaging species in Wisconsin
Large holes in leaves and heads
Often extensive frass
Peak damage mid-season (June/July)

68
Cabbage Looper life cycle

Adult
Large, night flying moth
Hour glass marks
Eggs
Laid singly on undersurface
White, turning tan at hatch
round shaped
Larvae
5 instars 4-5 weeks
Green with white stripe
Loop when moving
Up to 2 inches in length
Pupa
Roughly spun silk cocoon
Underside of old leaves or on debris

69
Cabbage Looper

Occurrence
Does not overwinter, adults blow in (June/July)
2 generations per year, persisting in late season
Damage
Damage usually late season
Extensive leaf holes and head damage

70
Managing the Lep. Complex

Cultural
Use clean transplants
Biological
Good complex of parasites
Diamondback moth 70-90 parasitized
Imported Cabbage worm 30-60
Cabbage looper 10-30
Multiple species

71
Managing the Lep. Complex

Chemical
Pest Specific
Bacillus thuringiensis (Kurstaki Btk, or Azaiwi
Bta)
Many materials registered
e.g. Dipel, Thuricide, Biobit, Cutlass, etc.
Short persistence ? timing critical
Stomach poison ? coverage important
Weak on looper
Broad Spectrum
Pyrethroids
Multiple applications
Resistance can be a problem
Eliminate biological controls

72
Key Pest of Root Crops
Cabbage Maggot Life Cycle

Adult
Small grey/black fly
Similar to housefly
Eggs
Small, white
Laid in soil at base of plants
Larvae
White, legless maggots
4 instars up to 1/4
3-4 weeks per generation
3 generations per year
Pupa
Brown, oval shaped
In or close to the roots

73
Cabbage Maggot Life Cycle

Occurrence
Overwinters in soil as pupa
Adults emerge in spring
3 flight peaks
First peak is most serious and occurs at 300 heat
units or when lilacs bloom (May)
Damage
Larvae tunnel on root surface
May be secondary rot
Major importance on root crops
Causes wilting, death on head crops

300 DD
74
Cabbage Maggot Management

Cultural
Rotate crop away from overwintering site (1/4-1/2
mile)
Prevent egg laying with barrier, row cover
Predict egg laying with heat units (300 HU with
43F base)
Plant early or late to avoid eggs
Biological
Some egg predation by beetles
Chemical
None currently available
Diazinon withdrawn

75
Sporadic Pests of Cole Crops
Flea beetle (several species)

Appearance
Small, shiny black beetles
Hind legs enlarged for jumping
Overwinter as adults
2 generations per year
Damage
Adults chew small circular holes
Can kill small plants
Larvae in soil are not damaging

76
Flea Beetle Management

Cultural
Exclude adults with row cover
Attract adults to alternate trap crop (Indian
mustard)
Avoid early planting
Biological
No effective controls
Chemical
Spray to control adults
Carbaryl, pyrethroids
DO NOT disrupt biological controls for lepidoptera

77
Sporadic Pests of Cole Crops
Cabbage aphids

Appearance
Grey, waxy covered aphids in dense colonies
Multiple generations
Damage
Feeding results in leaf distortion
Head malformation can occur
Dense colonies disfigure heads
Contamination of produce is common

78
Cabbage Aphid Management

Cultural
None available except exclusion
Biological
Parasites and predators are effective
Chemical
No effective controls
Insecticidal soap may suppress colonies

79
Cabbage Aphid Natural Controls
80
Putting together a biologically-based management
program for cole crops

3 requirements
Existing or obtainable natural enemies for key
pests
Pest specific insecticides to conserve natural
enemy control
Non-disruptive controls for sporadic pests

81
Natural Occurring Parasitization of Lepidoptera
Diadegma insulare

Diamondback moth 70-90
Imported cabbage worm 30-60
Cabbage looper 10-30

Cotesia glomerata
Pteromalus puparium
Trichogramma
Copidosoma floridanum
82
Parasites of Diamondback Moth

Diadegma insulare is primary parasite
Stings mid-stage larvae with single egg
Kills pupa
Replaces host pupa in case

83
Parasites of Imported Cabbage Worm

Cotesia glomerata
Stings small larvae and inserts several eggs
Larvae develops until parasites pupate
20-50 parasites emerge from late instar
Pteromalus puparum
Stings pupa
Eggs divide
Parasite larva kill host pupa
Up to 200 parasites emerge

84
Parasites of Cabbage Looper

Trichogramma
Tiny wasp lays egg in host egg
Parasite kills egg and emerges
Copidosoma floridanum
Tiny wasp lays egg in host egg
Host continues to develop
Parasite divides and kills late instar larvae
200-400 parasites emerge
Voria ruralis
Large fly stings small host larvae
Larva and parasites develop
Large larva killed and 2-3 parasites emerge

85
Pest Specific Insecticides for Key Pests

Control lepidoptera at thresholds when needed
Conserve beneficial organisms

86
Non-disruptive controls for sporadic pests

Cabbage maggot
Timing or avoidance
Row cover
Rotation of crop
Aphids
Predators
Parasites
Flea beetles
Trap crops (mustard)

87
Cole Crop insect control - Summary
Pesticide-reliant crop where biological control
can replace insecticides as the predominant
approach

Manage key lepidopteran pest complex with
combinations of
Biological control with parasites
Soft biological insecticides
Manage other pest with tactics which will not
interfere with biological control
Cabbage maggot ? cultural/physical
Aphids ? predators
Flea beetle ? rowcover

88
Snap beans - green, wax, lima, runner -

80,000 Acres, worth 36 million
Virtually all processed
Grown throughout the state
Janesville-Antigo
Short growing season, 55-60 days
Often multiple plantings

89
Snap bean insect control

Relatively few insect pests
Highly pest resistant plant
Insecticide use is heavy solely to meet
consumer demand
Ecology, biology of key pests has reduced
insecticide use dramatically
Fresh and home garden production requires little
insect control

90
Snap bean Key insect pests

European corn borer
Potato leafhopper
Seed corn maggot

91
Seed corn maggot life cycle

Larvae
White legless maggots
4 instars up to ¼
2-4 weeks to pupation
4-5 generations/year
Broad host range
Pupae
Brown, oval, in soil

Adult
Small grey black fly
Similar to house fly
Eggs
Small, white
Laid in soil over germinating seeds

92
Seed corn maggot host range

Wide host range
Can develop on organic matter also

Crop Susceptibility
93
Seed corn maggot

Occurrence
Overwinter in soil as pupa
Adults emerge in spring
4-5 generations/year. 2nd adult peak in May/June
is usually most serious
Damage
Larvae hatch and tunnel in germinating seeds
Larvae feed in seed and developing plant and
prevent emergence or severely distort plant.
Moderate feeding may injure 1st leaves only
giving crop a ragged appearance
Cool weather, which delays plant emergence
increases severity of damage
Plants compensate well for damage

94
Seed corn maggot management

Cultural
Prevent egg laying with row cover
Speed up germination pre-sprout, mulch, warm
soil
Avoid green manure
Biological
Predacious soil beetles
Fungal epidemics
Chemical
None available
Seed treatments used commercially

95
Potato leafhopper

Appearance
Adults, small (1/8) wedgeshaped, bright green
Rapid movement
Nymphs, yellow-green, lack wings
Occurrence
Does not overwinter in Wisconsin
Adults migrate from gulf states
Arrive June, 2-3 generations/year
Very broad host range
includes potatoes, beans, alfalfa
Can infest quickly

96
Potato leafhopper -damage

Both adults and nymphs feed
Sucking mouthparts
Saliva clogs plant, causes yellowing, leaf
necrosis
Can kill young plants quickly
May only cause stunting

Uninfested Infested
97
Potato leafhopper control

Cultural
Row cover
Plant early to avoid
Biological
No effective controls
Chemical
Monitor often
Treat only when threshold exceeded (1/sweep)
Do not let nymphs build up
Control is effective if needed
Carbaryl
Pyrethroids
Insecticidal soap

98
European corn borer
Key pest for processing industry gardeners can
ignore damage

Occurrence
Native to Wisconsin
Broad host range
Beans, sweet corn, field corn, potatoes, peppers
2-3 generations/year

99
European corn borer life cycle

Larva
Overwinter in corn stalks
5 instars (2-4 weeks)\1st and 2nd external
Large larvae are borers
Pupae
Inside stems
10-14 days

Adult
Night flyers
2 normal flight peeks June-August
600 HU and 1700 HU
Live in grass action sites
Eggs
Laid in masses (20-50)
Overlap like scales
White yellow
Black dots at hatch
5-7 days

100
European corn borer damage

If pods present they are preferred
Serious problem only if you can the worm

Later instars bore into stems
Plants easily compensate

Threshold of 1 pod/1000 for rejection

Small larvae external
Little damage

101
Snap bean self-defense against insects

Impailed larvae desiccate
98 of larvae killed!

Snap beans covered with hooked hairs
Protect against insects

Small larvae move from egg to flowers/pods

102
Cornborer management

1. Predict flight with heat units
1st 600 HU, 2nd 1700 HU
3rd generation possible in warm
years (2800 HU)
2. Monitor flights
State network of flight traps
DATCP survey
Walk action sites
3. Treat only plants with pods
30 days pre-harvest 7 days pre

103
Corn borer summary -beans

Fresh market, home owner can ignore damage
Taking advantage of natural plat defense
Processing
Use ecology, behavior to predict and monitor
Treat only when pest is present
Treat only if crop is susceptible
Applications reduced from 5-6 on all acreage to
1-2 on half acreage

104
Sporadic pests of snap beans

Need management only occasionally
Plant bugs tarnished plant bug
Aphids soybean aphid (recent)
Borers common stalk borer
Beetles bean leaf beetle, Mexican bean beetle
Mites 2-spotted spider mite

105
Sporadic pests of snap bean tarnished plant bug

Occurrence
Overwinters in field edges
May move from alfalfa
Damage
Feeds by sucking sap
May cause pod drop

106
Tarnished Plant Bug - Control

Cultural
Avoid planting next to alfalfa
Control weeds and edges
Biological
None
Chemical
Rarely needed
Threshold 2/sweep in bud stage
Pyrethroids effective

107
Sporadic pests of snap bean Soybean aphid

Occurrence
Recent introduction from China
Overwinters on buckthorn
Moves to soybean in June
Winged migration to snap bean in late July
Nymphs do not survive on snap bean
Damage
Primarily as virus vector late plantings
Large numbers of winged aphids can cause
temporary phytotoxicity

108
Soybean Aphid Management

Cultural
Plant early to avoid infestation
Biological
Predators are not effective Asian ladybeetle
only on soybeans
Chemical
Not required for fresh market

109
Sporadic pests of snap bean Common stalk borer

Occurrence
Overwinters as egg in grass
Larva tunnels in grass when small,move to crop
edge
Adult night flying moth
Larvae very active
Damage
Larva bores into stems and pods
Moves in from field edges
Primarily a contaminant

110
Common Stalk Borer Management

Cultural
Mow grass/weed edges
Can attack wide range of plants
Biological
None effective
Chemical
Rarely needed
Pyrethroids effective as edge treatments

111
Sporadic pests of snap bean Bean Leaf Beetle

Occurrence
Variable colors, spotted, brown, red
All have black V mark on wings
Overwinter as adults, 2 gens/year
Primarily a southern pest of soybean
Damage
Adults eat extensive holes
Pods also deformed
Larvae feed in soil, not damaging

112
Bean Leaf Beetle Management

Cultural
Plant late to avoid 1st generation adults
Row cover for 2nd generation
Avoid planting adjacent to soybeans
Biological
None are effective
Chemical
Treat if defoliation is over 10 or if pods are
present
Carbaryl or pyrethroids are effective

113
Sporadic pests of snap bean Mexican Bean Beetle

Occurrence
Overwinters as adult in protected locations.
Rare in Wisconsin
Adults (yellow with black spots), eggs (yellow
masses), and larvae (yellow spinney) are
distinctive
2 generations per year
Damage
Adults and larvae feed extensively on leaves
Pods deformed if present

114
Mexican Bean Beetle Management

Cultural
Avoid planting beans where beetle is established
Clean up overwintering protection
Plant late
Biological
None are effective
Chemical
Treat if defoliation is over 10 or if pods are
present
Carbaryl or pyrethroids are effective

115
Sporadic pests of snap beans spider mites

Occurrance
Usually occur in hot dry conditions
More severe in dusty, road side locations
Multiple generations on undersurface of leaf
Damage
Adults feed in large numbers on leaf surface
causing silvering
Lower surface often covered with webbing

116
Spider mite management

Cultural
Maintain good plant growth, irrigate
Avoid dusty roads
Biological
Several effective predators
Avoid broad-spectrum insecticides
Chemical
Do not use

117
Sweet corn insect control

Major canning crop in Wisconsin
Fresh market acreage increasing
Insect pests primarily ear feeders

118
Sweet corn key insect pests

Lepidopteran species complex
European corn borer (mid/late)
Corn earworm (late)
Fall armyworm (occasional)

119
European corn borer
Major pest of sweet corn, processing and fresh

Occurrence
Native to Wisconsin
Broad host range
Beans, sweet corn, field corn, potatoes, peppers
2-3 generations/year

120
European corn borer life cycle

Larva
Overwinter in corn stalks
5 instars (2-4 weeks)l
Large larvae are damaging borers
Pupae
Inside stems
10-14 days

Adult
Night flyers
2 normal flight peaks June-August
600 HU and 1700 HU
Live in grass action sites
Eggs
Laid in masses (20-50)
Overlap like scales
White yellow
Black dots at hatch
5-7 days

121
European corn borer damage
2nd generation
1st generation

1st generation (June) feeds in whorl and stalk
2nd generation (August-Sept) feeds directly on
ear

122
Corn Earworm life cycle

Larva
Brown or green with stripe
Feed primarily on ear tips
Late season

Adult
Does not overwinter in WI
Moths fly in on storms from South
Early infestation not a problem usually
2 generations
Eggs
Laid singly on silks
Hatch 5-7 days

123
Sweet corn insects managing worms

Corn borer
Predict ECB flights with heat
units 600, 1700 HU
Monitor egg masses on plants
Monitor adults with black light
Corn earworm
Monitor 2nd generation-pheromone traps
Complex
Treat only when insects and ears are present

124
Managing worms on sweet corn

Cultural
Early plantings avoid damage
Biological
Effective parasites are present, but do not
protect ears
Chemical
Protect only vulnerable crop stage (July-Sept)
when pests present
Pyrethroids are effective

125
Sporadic pests corn rootworm

Occurrence
Western (striped) and Northern (green) overwinter
in WI as eggs in soil
Southern (spotted) migrates from south
Adults lay eggs in corn fields in Aug.
Damage
Larvae from overwintered eggs feed on roots
lodging
Adults feed on silks and may cause poor
pollination

126
Corn rootworm -control

Cultural
Rotate crop (dont follow corn)
Northern RW has evolved to lay
eggs on soybean
Biological
None effective
Chemical
Treat adults only if silks present
and 5 adults/plant
Carbaryl or pyrethroids

127
Sporadic pests -corn leaf aphid

Occurrence
Build up rapidly on tasseling corn
Multiple generations
Damage
Rarely a problem
Late plantings only
Threshold 50 plants with 50 aphids

128
Corn leaf aphid control

Cultural
Early plantings avoid infestation
Biological
Very effective
Predators and parasites
Chemical
Rarely needed
Use threshold and rely on biological

129
Sporadic pests common stalk borer

Occurrence
Occasional pest on edges of crop
Overwinter as eggs in grass
Larvae move to crop
Damage
Tunnel in stems on edges

130
Common stalk borer control

Cultural
Mow edges to control grasses
Avoid grass areas
Biological
None effective
Chemical
None effective

131
Pepper Insect Control

Processing and fresh in Wisconsin
Bell and hot peppers have similar problems
Insects are usually only of minor importance

Key insect pests
European corn borer
Green peach aphid

132
European corn borer

Occurrence
Overwinters as larva in corn
Only 2nd generation infest peppers
August/September
Damage
Egg masses laid on leaves
Small larvae bore into fruit
Often near stalk
Larvae develop internally
Fruit rot is secondary

133
European Corn Borer control

Cultural
Plant early to avoid 2nd generation
Do not plant adjacent to sweet corn
Discard infested fruit
Biological
None effective
Chemical
Only use for 2nd generation protection
Only use if adult pressure is high
Pyrethroids are effective
Pymethrin, cyfluthrin

134
Green Peach Aphid

Occurrence
Winged aphids infest July/August
Multiple generations of wingless forms
Damage
Heavy infestation can wilt plants
Honeydew contaminates fruit may be sooty mold
Rarely a yield problem

135
Green peach aphid control

Cultural
Early planting
Biological
Effective
Predators and parasites
Chemical
Avoid use if possible to preserve natural control
Only esfenvalerate, acephate are effective
Soapy water may reduce

136
Tomato Insect Control

Fresh market only in Wisconsin
Staked or field
Insect problems are usually minor

137
Insect Pests of Tomato
No key pests all are sporadic

Tomato fruitworm (corn earworm)
Tomato hornworm
Aphids
Cutworms
Leafminer
Whitefly

138
Tomato Fruitworm (corn earworm, cotton bollworm)

Adult
Does not overwinter
Adults fly in
2 generations
Eggs
Laid singley on leaves
Hatch in 5-7 days
Feed externally on leaf and then bore into fruit
Larvae
Develop inside fruit
Can be brown or green

139
Tomato fruitworm

Occurrence
2nd generation only Aug/Sept
Damage
Small larvae feed on leaves
Larger bore into fruit
Develop internally
Infested fruit may color early or rot
This is a major pest in CA and FL

140
Tomato fruitworm control

Cultural
Plant early to avoid
Discard infested fruit
Biological
Effective parasites
But will not prevent damage
Chemical
Rarely necessary
Disrupts natural control of other pest (leaf
miner, aphid)

141
Tomato Hornworm Life Cycle

Adult
Large Hawk moth
Resembles hummingbird
Sips flower nectar
Eggs
Eggs large, round
Laid on leaves
Parasites and predators common
Larvae
Green with horn
Up to 2-3
Several stages
Pupae
Brown with handles
In soil

142
Tomato hornworm

Occurrence
Overwinters as pupa
Large hawk moths emerge
2 generations per year
Damage
Larvae consume lots of foliage
Occasional fruit feeding

143
Tomato hornworm control

Cultural
Remove larvae from plants and squash!
Biological
Very effective usually
Both predators (eggs) and parasites (larvae)
Chemical
Avoid if possible to preserve natural control
Bt is effective

144
Tomato insect pests - Cutworms

Occurrence
Several species involved
Early season
Damage
Cut plants at night

145
Cutworm control

Cultural
Protect plant with barrier, row cover
Control weeds/debris
Biological
Not effective
Chemical
Not effective

146
Tomato leafminer

Occurrence
Rarely damaging in Wisconsin
Biologically controlled
Avoid insecticide disruption
Major secondary pest in CA and FL

147
Aphids Potato aphid

Occurrence
Overwinter on rose
Multiple generations on tomato
Terminals usually infested
Damage
Plant wilting if populations are high
Honeydew and sooty mold on fruit,predators common

148
Aphid control

Cultural
None effective
Biological
Very effective
Predators and parasites
Fungal diseases
Chemical
None are effective
Insecticidal soap

149
Whitefly

Occurrence
Overwinters only in protected areas or
greenhouses
Multiple generations
Damage
Usually not a problem in Wisconsin
May be honeydew, sooty mold on fruit
Serious virus vector in FL and CA

150
Whitefly control

Cultural
Only use clean transplants
Biological
None effective
Chemical
None are effective

151
Insect Control on Carrots

4-5000 Acres in Wisconsin
Processing and fresh
Cut/peel carrots not yet produced here
Few serious insect problems

Key Pest Aster leafhopper
152
Aster Leafhopper

Occurrence
Overwinter as eggs on small grains and weeds
1st adult infestation from migrants in April/May
Local adults in June
1-2 generations
Damage
Vector of aster yellows disease (phytoplasm)
Red leaves
Bushy new growth
Hairy roots
Also damages other crops

153
Aster Yellows

Onions
Young plants die
Bulbs sprout in storage

Carrots

Weeds
Disease reservoir
Marestail, pineapple weed
Many species

Lettuce and celery
Very severe

154
Aster leafhopper control

Cultural
Row cover early
Discard infected plants
Rarely over 10 infested
Biological
None effective
Chemical
Necessary only if commercial production
Pyrethroids at thresholds

155
Aster leafhopper control

Monitor migration, predict arrival
Measure yellows infectivity
Scout crop
Treat at aster yellows index

156
Carrot insect pests -sporadic

Green peach aphids
Problem only if insecticide disrupts control
Not economic usually
Carrot weevil
Adults overwinter on field edge
Rare in Wisconsin
Damage in early season
1 generation/year
Damage
Adults excavate cavity, lay eggs
Larvae tunnel in roots
Control
Do not grow carrots (1-2 years)!
Pyrethroids early on edge

157
Cucurbit Insect Control
melons
Squash, pumpkins
cucumbers

Insect management
Generally similar insect pests on all
Insects may be more severe on some

158
Insect Pests of Cucurbits
Seed corn maggot
Cucumber beetles
Squash vine borer
159
Seed corn maggot life cycle

Adult
Small grey/black fly
Similar to housefly
Eggs
Small, white
Laid in soil at base of plants
Larvae
White, legless maggots
4 instars up to 1/4
3-4 weeks per generation
3-5 generations per year
Pupa
Brown, oval shaped
In soil

160
Seed corn maggot

Occurance
Overwinter in soil as pupa
Adults emerge in spring
4-5 generations/year. 2nd adult peak in May/June
is usually most serious
Damage
Larvae hatch and tunnel germinating seeds
Larvae feed in seed and developing plant and
prevent emergence or severely distort plant.
Moderate feeding may injure 1st leaves only
giving crop a ragged appearance
Cool weather, which delays plant emergence
increases severity of damage

161
Seed corn maggot management

Cultural
Prevent egg laying with row cover
Speed up germination pre-sprout, mulch, warm
soil
Avoid green manure
Biological
Predacious soil beetles
Fungal epidemics
Chemical
None available
Seed treatments used commercially

162
Cucumber beetles

Occurrence
Both striped and spotted beetles overwinter as
adults
Appear early, 2 generations/year
Striped is most severe
Damage
Adults can feed on foliage early or fruit late
Most damage is from bacterial wilt
Closely associated with beetle
Single beetle can infest plant
No cure for bacteria, control through vector
Cucumbers, most melons (not watermelon),
butternut and hubbard squash are susceptible

163
Cucumber beetle control