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.
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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
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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

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

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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

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

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

17

• Adults walk to crop
• Damage depends on temperature
• May - June

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

19

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

20

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

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• 4th instar larva

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• Larval feeding
• 4th instars leave plant and pupate
• in soil

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

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• Summer adults emerge in July
• Very active
• Very hungry

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

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• 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

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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??

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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

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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

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

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Biological control of aphids

• Usually effective
• Avoid disruption

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

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

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Flea beetle control

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

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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

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Worm control

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

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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

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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

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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

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Soil insect control

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

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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

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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.
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Insect Pest Complex
Key Pests - Lepidoptera
Diamond back moth
Imported cabbage worm
Cabbage looper
Sporadic Pests
Cabbage maggot
Flea beetle
Cabbage aphid
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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

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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
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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

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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

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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

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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)

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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

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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

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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

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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

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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

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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
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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

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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

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Cabbage Aphid Natural Controls
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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
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Parasites of Diamondback Moth

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

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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

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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

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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

• Cultural
• Plant late
• Eliminate weeds, weedy edges
• Row cover early
• Biological
• None effective
• Chemical
• Use if wilt is a problem
• Avoid flowering to protect bees
• Pyrethroids are effective

164
Squash vine borer life cycle

• Adult
• Day flyers
• Resemble wasps
• 1 generation
• Eggs
• Button shaped
• Laid near base
• June/July
• Larvae
• White
• Tunnel in stems

165
Squash vine borer

• Occurrence
• 1 generation per year
• Eggs laid in June/July
• Coincides with chickory bloom
• Damage
• Larvae tunnel in stem
• Plant wilts
• Most severe on winter squash

166
Squash vine borer control

• Cultural
• Protect base of plants (row cover)
• Physically kill larvae
• Biological
• None effective
• Chemical
• Pyrethroids,carbaryl

167
Cucurbit sporadic insect pests
Squash bug
Aphids
Spider mite
168
Sporadic pests squash bug

• Occurrence
• Adults are large black bugs which aggregate on
  plants
• Round eggs are laid in neat rows
• Nymphs are white/grey
• Damage
• Phytotoxic saliva causes wilting
• Control
• Few effective controls
• Treat early if present

169
Sporadic pests melon aphid

• Occurrence
• Winged aphids infest in mid season
• Multiple generations of wingless
• Damage
• High populations wilt plants
• Honeydew and sooty mould
• Viruses transmitted rapidly

170
Melon aphid control

• Cultural
• Reflective mulch to repel aphids
• Black plastic, white plastic, foil
• Biological
• Effective predators
• Chemical
• Few affective
• Insecticidal soap

171
Sporadic pestsspider 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

172
Spider mite management

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