Jon Turmel-Vegetable Insect Management

Vegetable Insect Management
PSS 124 Vegetable Crop Production

Jon P. Turmel, State Entomologist

VT Agency of Agriculture

Waterbury, Vermont

November 30, 2006

Transplants in the Greenhouse
Aphids Melon, Potato, Foxglove, Green PeachDipterans Fungus gnat, Shore fly, Humpbacked fly, Moth fly, LeafminerMites Two-spotted spider, CyclamenWhiteflies Greenhouse, Silverleaf aka. Sweetpotato
aphid

Aphids

green peach

foxglove

melon

potato

Aphids
High Fecundity Rates: Explosive Parthenogenetically, paedogenesis, sexualVectorsOviparous, viviparousResistance increased production of an enzyme

Aphid Morphology

Aphid Morphology
Tubercles

Aphids

Tended by ants

Vectoring potato X virus

Sooty mold

Root aphids

Aphid Parasitoids

Aphid predators

Adult lady bird beetles

Lady bird beetle larva

flower fly Adult syrphid

Syrphid larva

Crucifer Insect Pests
Cabbage MaggotCabbage AphidsLepidopteran complex
* Diamondback Moth

* Imported cabbageworm

* Cabbage Looper

Cabbage Maggot
Delia radicum (L.)

Cabbage Maggot
life cycle
Overwinters as a pupa and emerges in mid-MayPrefers cool, moist weatherFirst generation most damaging2-3 generations/yearLarva completes cycle in 3 weeksFeeds on all crucifers, beets, celery and onion
Adult

Cabbage Maggot
Management
Monitor using yellow-pan water traps200 GDDFull bloom of Serviceberry, McIntosh and Cortland apples

Cabbage Maggot
Management
Protection of roots and stems Insecticide application as drench pre or post plantingDrench (2-3) at five week intervalsIn furrow granularSpunbonded row covers (rotated only)

Cabbage aphids
Aggregated vs uniformNo threshold at this time but when head is formed the threshold is zeroSerious vectorSelective insecticidesSelective non-target insecticidesCheck for parasite pop.Turnip-light oil reduces mosaic virus transmission

Lepidopteran Complex
Diamondback Moth, Imported Cabbageworm and Cabbage Looper

Diamondback moth adult

Imported cabbageworm adult

Cabbage looper adult

Diamondback Moth
Plutella xylostella (L.)
Overwinters ?Not known to be a vectorLarva = 4 instars in 10-14 daysPupa = 14 daysFemale lays 160 eggs in 2 weeks
larva

pupa

Diamondback moth
damage

Imported Cabbageworm
Pieris rapae

egg

hatching

larva

pupa

Overwintering stage

4-8 days

8-20 days

24-31 days

Imported Cabbageworm
damage

broccoli

cabbage

Cabbage Looper
Trichoplusia ni (Hubner)

Eggs hatch in 3-4 days

Larva have 5 instars in 3 weeks, most damage is done in last 2 instars

As a pupa for about 2 weeks

adult

does not overwinter in VT

Cabbage Looper
damage

cabbage

broccoli

Lepidopteran complex
management
Young plants = 35% infestedMore mature = 20%10-15% on kale, collards and mustardDiamondback has become resistant, alternate between effective treatmentHigh volumes give better results (50 gal/A)Bt kurstaki, higher rate in cool conditionsBt aizawai works better on resistant DBMMUST alternate with synthetic insecticide or spinosad (aerobic fermentation by product of a soil bacterium) Avoid southern transplants

Potato Insect Pests
Aphids green peach, potato, foxglove, buckthorn, melonColorado Potato BeetlePotato leafhopper

Colorado Potato Beetle
Leptinotarsa decemlineata
Overwinters as an adult in and around potato fields2 generations per year with a third in some yearsBoth adult and larva feedFemale lays 300-500 eggsImplicated as a vector but not yet confirmed
larva

larval feeding


Adult feeding

Newly hatched eggs

Female laying eggs

Larval feeding

Colorado Potato Beetle Management
Rotate to nonhost crops. This includes overwintering sites that border previous season plantingsAlternate different groups of insecticides throughout the seasonUse mechanical barriers such as trench traps and/or trap crops Determine Action Thresholds. Crop can withstand 15% defoliation without effecting yieldsNone of the present commercial cultivars of potato is resistant to the CPBBiocontrol including insects, parasitoids and predators

Trench Trap
Plastic lined trench trapPlace next to overwintering areas at least one week prior to adult emergence1-2 feet deep and 6-24 inches wide at topU or V shaped with walls 65-90 degree slope

Action Threshold Determination
Walk the field in a V, W or X patternSelect 50 potato stalks at random intervalsCount adults, large larvae (>1/2 grown), small larvae (< half grown)Compare counts to the table (on next slide)If numbers is high, treatment is warrantedIf low, no treatmentIf between, no treatment but re-check in 3-5 days

Action Thresholds*

Life Stage

Number of CPB per 50 Stalks

Low

High

Adult

Small Larvae

Large Larvae

15 or fewer 25 or more



*Do not apply to B.t. products and are for midseason. Late season plants can tolerate more defoliation without affecting yields

Use 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 hatchedIf 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!

Potato leafhopper
Empoasca fabae

Potato Leafhopper

nymph

adult

adult

adult

Potato Leafhopper
Overwinters along the Gulf Coast on southern pineMoves north on storm fronts and arrives in VT mid-JuneVery low numbers can cause significant crop lossesHost of over 100 braod-leaved plants

Potato Leafhopper
Both nymphs and adults cause damageNo disease is known to be transmitted by the potato leafhopperCauses hopper burnThreshold is 10 nymphs per 100 plants. Currently, no cultural or biological controls are available
sweeping

hopper burn

#1 Enemy
(In my humble opinion)

Tarnished Plant Bug
Lygus lineolaris (Palisot de Beavois)

Tarnished Plant Bug
Feeds on over 300 different plants (>50 of economic importance)Introduces a toxic saliva into the plant while feedingCauses leaf distortion, black joint, scarring, discoloration, bud abortion, dwarfed and pitted fruit

Tarnished Plant Bug

egg

nymph

Bio-control

Peristenus digoneutis

Tarnished Plant Bug
Damage

Celery

Tomato

Amaranth

Eggplant

Tarnished Plant Bug Damage in Strawberry

Corn Insect Pests
European Corn BorerCorn EarwormNorthern/Western Corn RootwormFall ArmywormBlack CutwormCommon Armyworm

European Corn Borer
Ostrinia nubilalis
Feeds on over 200 wild and herbaceous plantsDifferent strains cause different types of damage to cornVector of shank, stalk and ear rot fungi1-2 generations/year

European Corn Borer
damage

beans

Bell pepper

popcorn

wheat

European Corn Borer
eggs

black headed stage

newly hatching eggs

egg mass on corn leaf

European Corn Borer
larvae

5 instars

1st instar feeding

larval feeding on ear

European Corn Borer

shot holes

larval tunnel in midrib

larval tunnel in ear stalk

larval tunnel in stalk

European Corn Borer

Pupae in stalks

European Corn Borer
Plowing down in fallwas the LAW!
75% of the overwintering larvae in a corn field can be eliminated

European Corn Borer
Scouting

Pulling whorl

Unfolding whorl

Scouting for eggs

Blacklight trap

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

European Corn Borer
When corn is pretassel and 15% of these young tassels show damageEarlier treatments are of no value2nd generation in mid-July to Sept. will attack ears. Must protect developing ears

European Corn Borer

Conventional corn whorl damage

Transgenic corn in same field

Corn Earworm
Helicoverpa zea aka. Heliothis zea
Native to the AmericasMost destructive after E. Corn BorerDoes not overwinter in VTMolds become toxinsLarvae may destroy silk before pollination is complete$$$ when severe

Corn Earworm

Adult usually arrives mid-July

Eggs in silk for 3 days

pupae

Larva feeding for about one month

Corn Earworm
Monitoring for adults and treatment schedule

Pheromone baited heliothis traps

Blacklight trap

Any Questions?

Documents

Jon Turmel-Vegetable Insect Management