Vegetable Insect Management PSS 124 Vegetable Crop Production

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Vegetable Insect ManagementPSS 124 Vegetable
Crop Production

• Jon P. Turmel, State Entomologist
• VT Agency of Agriculture
• Waterbury, Vermont
• November 30, 2006

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Transplants in the Greenhouse

• Aphids Melon, Potato, Foxglove, Green Peach
• Dipterans Fungus gnat, Shore fly, Humpbacked
  fly, Moth fly, Leafminer
• Mites Two-spotted spider, Cyclamen
• Whiteflies Greenhouse, Silverleaf aka.
  Sweetpotato

aphid
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Aphids
green peach
foxglove
melon
potato
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Aphids

• High Fecundity Rates Explosive
  Parthenogenetically, paedogenesis, sexual
• Vectors
• Oviparous, viviparous
• Resistance increased production of an enzyme

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Aphid Morphology
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Aphid MorphologyTubercles
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Aphids
Tended by ants
Vectoring potato X virus
Sooty mold
Root aphids
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Aphid Parasitoids
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Aphid predators
flower fly Adult syrphid
Adult lady bird beetles
Syrphid larva
Lady bird beetle larva
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Crucifer Insect Pests

• Cabbage Maggot
• Cabbage Aphids
• Lepidopteran complex
• Diamondback Moth
• Imported cabbageworm
• Cabbage Looper

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Cabbage MaggotDelia radicum (L.)
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Cabbage Maggotlife cycle

• Overwinters as a pupa and emerges in mid-May
• Prefers cool, moist weather
• First generation most damaging
• 2-3 generations/year
• Larva completes cycle in 3 weeks
• Feeds on all crucifers, beets, celery and onion

Adult
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Cabbage MaggotManagement

• Monitor using yellow-pan water traps
• 200 GDD
• Full bloom of Serviceberry, McIntosh and Cortland
  apples

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Cabbage MaggotManagement

• Protection of roots and stems
• Insecticide application as drench pre or post
  planting
• Drench (2-3) at five week intervals
• In furrow granular
• Spunbonded row covers (rotated only)

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Cabbage aphids

• Aggregated vs uniform
• No threshold at this time but when head is formed
  the threshold is zero
• Serious vector
• Selective insecticides
• Selective non-target insecticides
• Check for parasite pop.
• Turnip-light oil reduces mosaic virus
  transmission

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Lepidopteran ComplexDiamondback Moth, Imported
Cabbageworm and Cabbage Looper
Diamondback moth adult
Imported cabbageworm adult
Cabbage looper adult
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Diamondback MothPlutella xylostella (L.)

• Overwinters ?
• Not known to be a vector
• Larva 4 instars in 10-14 days
• Pupa 14 days
• Female lays 160 eggs in 2 weeks

larva
pupa
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Diamondback mothdamage
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Imported CabbagewormPieris rapae
egg
hatching
4-8 days
pupa
larva
24-31 days
8-20 days
Overwintering stage
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Imported Cabbagewormdamage
broccoli
cabbage
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Cabbage LooperTrichoplusia ni (Hubner)
Eggs hatch in 3-4 days
As a pupa for about 2 weeks
Larva have 5 instars in 3 weeks, most damage is
done in last 2 instars
does not overwinter in VT
adult
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Cabbage Looperdamage
cabbage
broccoli
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Lepidopteran complexmanagement

• Young plants 35 infested
• More mature 20
• 10-15 on kale, collards and mustard
• Diamondback has become resistant, alternate
  between effective treatment
• High volumes give better results (50 gal/A)

• Bt kurstaki, higher rate in cool conditions
• Bt aizawai works better on resistant DBM
• MUST alternate with synthetic insecticide or
  spinosad (aerobic fermentation by product of a
  soil bacterium)
• Avoid southern transplants

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Potato Insect Pests

• Aphids green peach, potato, foxglove,
  buckthorn, melon
• Colorado Potato Beetle
• Potato leafhopper

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Colorado Potato BeetleLeptinotarsa decemlineata

• Overwinters as an adult in and around potato
  fields
• 2 generations per year with a third in some years
• Both adult and larva feed
• Female lays 300-500 eggs
• Implicated as a vector but not yet confirmed

larval feeding
larva
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Colorado Potato Beetle
Adult feeding
Female laying eggs
Newly hatched eggs
Larval feeding
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Colorado Potato Beetle Management

• Rotate to nonhost crops. This includes
  overwintering sites that border previous season
  plantings
• Alternate different groups of insecticides
  throughout the season
• Use mechanical barriers such as trench traps
  and/or trap crops

• Determine Action Thresholds. Crop can withstand
  15 defoliation without effecting yields
• None of the present commercial cultivars of
  potato is resistant to the CPB
• Biocontrol including insects, parasitoids and
  predators

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Colorado Potato BeetleTrench Trap

• Plastic lined trench trap
• Place next to overwintering areas at least one
  week prior to adult emergence
• 1-2 feet deep and 6-24 inches wide at top
• U or V shaped with walls 65-90 degree slope

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Colorado Potato BeetleAction Threshold
Determination

• Walk the field in a V, W or X pattern
• Select 50 potato stalks at random intervals
• Count adults, large larvae (gt1/2 grown), small
  larvae (lt half grown)

• Compare counts to the table (on next slide)
• If numbers is high, treatment is warranted
• If low, no treatment
• If between, no treatment but re-check in 3-5 days

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Colorado Potato BeetleAction Thresholds
Life Stage
Number of CPB per 50 Stalks
Low
High
Adult Small Larvae Large Larvae
15 or fewer 25 or more 75 or fewer
200 or more 30 or fewer 75 or
more
Do not apply to B.t. products and are for
midseason. Late season plants can tolerate more
defoliation without affecting yields
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Colorado Potato BeetleUse of Bacillus
thuringiensis tenebrionis

• Most effective against 1st and 2nd instar.
• First spray one-3 days after there is one or more
  egg masses per lant and 30 have hatched
• If densely populated and eggs are hatching
  continuously, reapply after 5-7 days

• Or, wait for later instars to appear, treat with
  a single application of Provado or SpinTor the
  start your application a week later.
• Death with Bt may take up to 5 days but feeding
  ceases within one hour. Be patient!

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Potato leafhopperEmpoasca fabae
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Potato Leafhopper
adult
adult
nymph
adult
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Potato Leafhopper

• Overwinters along the Gulf Coast on southern pine
• Moves north on storm fronts and arrives in VT
  mid-June
• Very low numbers can cause significant crop
  losses
• Host of over 100 braod-leaved plants

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Potato Leafhopper

• Both nymphs and adults cause damage
• No disease is known to be transmitted by the
  potato leafhopper
• Causes hopper burn
• Threshold is 10 nymphs per 100 plants.
• Currently, no cultural or biological controls are
  available

sweeping
hopper burn
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1 Enemy (In my humble opinion)
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Tarnished Plant BugLygus lineolaris (Palisot de
Beavois)
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Tarnished Plant Bug

• Feeds on over 300 different plants (gt50 of
  economic importance)
• Introduces a toxic saliva into the plant while
  feeding
• Causes leaf distortion, black joint, scarring,
  discoloration, bud abortion, dwarfed and pitted
  fruit

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Tarnished Plant Bug
egg
nymph
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Bio-control
Peristenus digoneutis
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Tarnished Plant BugDamage
Celery
Tomato
Amaranth
Eggplant
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Tarnished Plant Bug Damage in Strawberry
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Corn Insect Pests

• European Corn Borer
• Corn Earworm
• Northern/Western Corn Rootworm
• Fall Armyworm
• Black Cutworm
• Common Armyworm

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European Corn BorerOstrinia nubilalis

• Feeds on over 200 wild and herbaceous plants
• Different strains cause different types of damage
  to corn
• Vector of shank, stalk and ear rot fungi
• 1-2 generations/year

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European Corn Borerdamage
Bell pepper
beans
popcorn
wheat
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European Corn Borereggs
black headed stage
egg mass on corn leaf
newly hatching eggs
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European Corn Borerlarvae
5 instars
1st instar feeding
larval feeding on ear
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European Corn Borer
larval tunnel in midrib
shot holes
larval tunnel in stalk
larval tunnel in ear stalk
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European Corn Borer
Pupae in stalks
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European Corn BorerPlowing down in fallwas the
LAW!75 of the overwintering larvae in a corn
field can be eliminated
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European Corn BorerScouting
Pulling whorl
Unfolding whorl
Blacklight trap
Scouting for eggs
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European Corn Borer

• No need to survey before corn is knee high
  because of the high concentration of DIMBOA-
  kills young larvae

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European Corn Borer

• When corn is pretassel and 15 of these young
  tassels show damage
• Earlier treatments are of no value
• 2nd generation in mid-July to Sept. will attack
  ears. Must protect developing ears

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European Corn Borer
Transgenic corn in same field
Conventional corn whorl damage
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Corn EarwormHelicoverpa zea aka. Heliothis zea

• Native to the Americas
• Most destructive after E. Corn Borer
• Does not overwinter in VT
• Molds become toxins
• Larvae may destroy silk before pollination is
  complete
• when severe

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Corn Earworm
Adult usually arrives mid-July
Eggs in silk for 3 days
pupae
Larva feeding for about one month
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Corn EarwormMonitoring for adults and treatment
schedule
Pheromone baited heliothis traps
Blacklight trap
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Any Questions?
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