VEGETABLE INSECT PESTSScouting Techniques & Management

Dr. Ayanava MajumdarExtension Entomologist, ACES

Gulf Coast Research & Extension Center8300 State Hwy 104, Fairhope, Alabama 36532

Cell phone: 251-331-8416azm0024@auburn.edu

Workshop Objectives Take the quiz!• Basic concepts of IPM• Types of insect injury to plants• Tomato insect pests• Insect pests of cruciferous crops• Common “on-the-shelf” insecticides• Commercial insecticidesComplete the quality survey

First know the definitions…INJURY

DAMAGE

Damage = injury + economic loss

Plant injury by INSECTS• Direct injury caused by feeding:

chewing mouthparts VS. sucking mouth parts

• Direct injury caused during oviposition: dimpling on tomato by thrips egg-laying

Image: UFL IFAS Ext.

Image: UFL IFAS Ext.

Plant injury by INSECTS

• Indirect injury from insect products: honeydew causes sooty mold (aphids, whiteflies)

Image: TopTurf.netImage: Iowa State

Plant injury by INSECTS

• Injury from disease transmission: aphids, thrips

Transmit cucumber mosaic virus (CMV), potato virus Y (PVY)

Transmit tomato spotted wilt virus (TSWV)

Images: U Wisconsin & Queensland Govt., Australia

Plant injury by INSECTS

Is it really an INSECT injury?

Image: Missouri Bot. Garden

Key steps to diagnosis:

• Define the problem

• Look for patterns: abiotic problems have patterns!

• Find a reasonable scouting technique

• How fast are symptoms spreading? (time-factor)

• Process of elimination to arrive at a diagnosis

VS.

TOMATO INSECT PESTS

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Scouting for aphids• Scout early in season, search under leaves and stem

• Winged aphids may indicate migration

• Record the number of leaves with aphids present, then mark the area (distribution is highly clumped)

• ET = 50% leaves have aphid

• Watch for presence of ants that feed on honeydew

• Watch for ladybeetles and lacewings

Scouting for thrips• Major damage: TSWV (disease)

• Mid-season damage: feeding in blossoms>>flower drop

• Late season damage: egg-laying on fruits>>dimpling + whitish spots

• Scout throughout the season, search terminal leaflets and buds. Carry 70% alcohol in vial or use beating technique.

• Resistant var. “Amelia”, “BHN 640/602”, Quincy, Taladega

Tobacco thripsWF thrips

Scouting for flea beetles• Sample the seedling plants (6-10 inch height)

• Estimate the level of defoliation

• Estimate the number of adults with a sweep net and relate it to foliar injury

• ET = 5-10% foliar injury

Scouting for CPB• Defoliation is less threatening on mature plants

• Beetle injury first on field margins

• Scout the short crop intensely (6 to 10 inch)

• Estimate the number of CPB on 10 plants

• ET = 5 beetles in short crop, 10% defoliation

Scouting for tomato fruitworm• This is a major pest. Mark the location with flag & mark your calendars!

• Use pheromone traps for monitoring flight

• ET = scout intensely for eggs/larvae if 7 adults per trap

• Scout for larvae during fruit set.

• ET = one larva per plant or one fresh injury per plant

• Improve scouting technique with experience

Emerging problem: Stink bugs

Has many host plants

Early attack can destroy blooms and late attack destroy fruits

Scouting for stink bugs

• Can you smell them in field?

• Try sweep netting to sample adults mid-morning

• Scout intensively when fruit formation begins: 10 plants per location

• ET: 0.25 stink bugs average per 10 plants during the green fruit stage

• Much research on trap crops (alfalfa, clover, sorghum)

Leaf-footed bugs

• Related to stink bugs• Emerging problem in

many states: Lousiana, Florida, California, Alabama

• Interesting behavioral issues

• Trap crops may work!

Scouting for tomato hornworm

Leave these caterpillars alone!

• Minor problem in commercial production (foliar damage only)

• Visual location, scout & hand-pick when possible

• There could be 3–4 generations per year, so late season buildup should be monitored

INSECT PESTS of COLE CROPS

Crucifer family of crops (list)• Cabbage• Broccoli• Cauliflower• Mustard greens• Brussels sprout• Kale • Collard• Turnip• Radish• Horseradish

Cabbage looper vs. Imported cabbageworm

Cabbage looper (CL) Imported cabbageworm (ICW)

Diamondback moth

• Larvae balloon from plant to plant

• Larva make shapeless holes, feeding in aggregates

• Cause head deformation

Scouting for caterpillar pestsCabbage looper Imported cabbageworm

• Look for larvae with 2-pairs of prolegs

• Look for frass at the base of head

• Use pheromone traps to monitor pop.

• ET = 10 % defoliation

• Look for white/yellow moths early in the season• Caterpillars camouflage with leaf midrib• ET = 10% defoliation

Diamondback moth

• Scout early in season• Pheromone traps• Ballooning caterpillars?• ET = 10% defoliation

Beet armyworm

Damage to pepper plant

• Early instars feed voraciously

• Are attracted to weak plants

• Damage more plants that they eat (cause early & late season problem)

• Dry weather is favorable

Cutworms

• Scout for egg masses and caterpillars

• Use a sweep net to sample moths around field edges

• Use pheromone trap for monitoring moth activity

• ET = 2-3% plants with egg masses, 1 larvae per 20 plants, 10% defoliated plants

Scouting for armyworm & cutworm

Armyworms

Cabbage aphid

Natural Enemies

CHOOSING THE RIGHT INSECTICIDE

(let’s go shopping!)

$9.76/pt

AI = horticultural oil

$7.99 for 24-oz RTU

AI = pyrethrin + canola oil or sulfur + pyrethrin

General purpose

insecticide

AI = malathion

$21/qt

+ MANY OTHER INSECTS

• Not for use on vegetables• Good fire ant control in lawn

and turf• Long residue in soil• May be expensive

AI = bifenthrin

Highly toxic to fish

AI = rotenone

Up to $9

Common soil bacterium

Best against small caterpillars

Apply when caterpillars are small

AI = Bacillus thuringiensis kurstaki

AI = Bacillus thuringiensis israelensis

Insecticidal soap• Not equal to your dish

detergent• OMRI approved• Do not apply in hot

weather• Spray on a test area

$7.85 RTU spray

2.5 Ga jug = $79

CHOOSING ENVIRONMENTALLY-

FRIENDLY INSECTICIDES(commercial veg. producers)

Spinosyn-based products

• Entrust is OMRI approved

• Very expensive ($600 per pound) but also very effective

• Entrust @ 2oz/A highest protection in Auburn trials against whitefringed beetles

• Works against many lepidopterans

• Spinetoram (2nd gen. spinosyn)• Excellent control of leps., thrips• Not for organic farming

Pyrethrin• Natural extract of

chrysanthemum flowers• OMRI approved• PyGanic for organic

producers• Pyrethrin + PBO

formulations are not organic• Pyrethrin + Rotenone not for

organic markets…

OMRI listedAI = pyrethrin + rotenone

• Natural insect growth disruptor• Effective against soft-bodied

insects

Azadirachtin

• Does not contain azadirachtin• 70% neem oil• Physical irritant• E.g., Monterey 70% (small

gardens), Trilogy 70% (large packaging)

Neem Oil

$16 per pint

Fungal microbial insecticides

$72 per quart2 quarts/A

Beauveria bassiana strain GHA

• soft-bodied insects such as whiteflies, thrips, aphids, psyllids, mealybugs, scarab beetles, plant bugs, loopers and weevils.

• Higher spore concentration than BotaniGard, 1 qt/A

Beauveria bassiana strain GHAFungal microbial insecticides

$399 per 2 gallons

Formulations by Certis USA

• Virus (occlusion bodies)• Very host specific• Heliothis spp., corn earworm, cotton bollworm,

tomato fruitworm, tobacco budworm

Bt aizawai

TRILOGY: NEEM OIL PRODUCT

Bio-based controls: are they cost effective?

Palumbo 2000

Bio-based controls: are they cost effective?

Palumbo 2000

Synthetic insecticides (old)Conventional products MOA

Aphids, flea beetles, whitefly

Stink bugs

Dimethoate, acetamiprid (Assail), imidacloprid (Admire Pro)

Bifenthrin & many pyrethroids

Pyrethroid -neonicotinoid (Nicotinic acetylcholine receptor agonists, sodium channel modulators)

Caterpillars (looper, tomato fruitworm, pinworm)

BifenthrinBeta-cyfluthrin (Baythroid)Lambda-cyhalo. (Warrior)Zeta-cyper. (Mustang Maxx)Esfenvalerate (Asana)Fenpropathrin (Danitol)

Sodium channel modulators

New chemistries MOA

Aphids, flea beetles, whitefly

Stink bugs

Flonicamid (Beleaf)Pymetrozine (Fulfill)

Spirotetramat (Movento)Spiromesifen (Oberon)

Feeding inhibitors

Acetyl CoA caboxylase inhibitor

Caterpillars (looper, tomato fruitworm, pinworm)

Thrips

Emamectin benzoate (Proclaim)

Flubendiamide (Synapse),Rynaxypyr (Coragen)

Indoxacarb (Avaunt)

Methoxyfenozide (Intrepid)

Spinetoram (Radiant)

Chloride channel activators

Ryanodine receptor modulators

Sodium channel blockers

Ecdysone receptor agonist

Spinosyn (nicotinic receptors)

Synthetic insecticides (new)

NEW RESOURCE: VEGETABLE ENTOMOLOGY DYNAMIC WEBSITE

Visit http://www.aces.edu/dept/com_veg/ or https://sites.aces.edu/group/commhort/vegetable/default.aspx

THANK YOU FOR YOUR PATIENCE

Please fill up and return the anonymous surveys that will be used to improve future workshops. Thank you again!

QUESTIONS?