Greenhouse Insect Biology and Management

Jen White & Ric BessinDept. Entomology

University of Kentucky

Pest management in greenhouses

Why are pests attracted to

greenhouses?Lots of foodGreat climateNo enemies

Outline

• Introduction to Integrated Pest Management• Biology of common greenhouse pests• Chemical controlsNext time:• Biological and Alternative controls

Integrated Pest Management

• Integration of tactics– Biological– Chemical– Cultural– Physical/mechanical

• More reliable control

Goal: Mitigate pest damage while protecting human health, the environment and economic viability

Components of an IPM Program

• Pest prevention• Pest identification• Monitoring and population assessment• Control action guidelines• Integration of tactics– Biological– Chemical– Cultural– Physical/mechanical

Prevention

Keep them out!• Inspect incoming stock– Isolation

• Mechanical exclusion• Weed removal– Inside and outside GH– No extra flowering ornamentals

• Prevent year-to-year carryover– Remove residues– Sanitize

Pest Identification

• Why is it important?– Misidentification can contribute to failure– Incorrect biological or chemical controls

Common Greenhouse Pests

• Mites• Thrips• Whiteflies• Aphids• Fungus gnats• Shore flies• Mealybugs• Others…

Characteristics–Small–Hidden–Short life cycle–Numbers build fast

Fungus gnat

Mealybug

Whitefly

Aphid

Mite

Shore fly

Thrips

Relative Sizes

Common Greenhouse Pests• Mites• Thrips• Aphids• Whiteflies• Mealybugs• Fungus gnats• Shore flies• Others…

• Tiny• Webbing

Mite identification

• Tiny• Webbing• Eight legs, no wings– NOT insects

• Two spots –• Two spotted spider mite

• Other species– Lewis, Broad, Cyclamen

Mite identification

Spider Mites

• Attack 300 + species of plants

• Life cycle in 8+ days

• Females lay 100+ eggs

• Sap feeders

• Under leaves, around buds

• Prefer tender leaves Two-spotted spider mite

Mites: Monitoring

• Scouting

– look for stippling, mottled leaves

– webbing

– premature leaf drop

• Examine under leaves

Mites: Management

• Cultural

–Reduce plant stress

– Spritz with water

Common Greenhouse Pests• Mites• Thrips• Aphids• Whiteflies• Mealybugs• Fungus gnats• Shore flies• Others…

Thrips Identification• Tiny• Yellow-ish• Linear• Most common:• Western flower thrips

Thrips Damage• Deformed leaves• Decaying flowers• Silvery, flecked scars• Black fecal spots

Thrips Biology

Pierce plant cells

Young growth and flowers

Tightly furled

Mainly females 150 to 300 eggs

Life cycle: 12+ days

Vector tospoviruses Impatiens necrotic spot virus (INSV)

Tomato spotted wilt virus (TSWV)

Western flower thrips

In soil

In plant

Thrips: Monitoring Early detection

Blue or yellow cards Minimum of 3

Placed near doors/vents

thrips sensitive plants

1 per 2000 ft2 minimum

Placed just above canopy

Can do a subset of grids

New cards periodically

Tap method

Same person, regular basis (weekly)

Thrips: Management

Cultural Control Remove weeds (that may

harbor viruses)

Crop alternation

Petunia as virus indicator plant Sensitive to virus

Not systemic

Use vegetative plants

Blue plastic plate to attract

Western flower thrips

“Summer madness”“Cascade blue”

Common Greenhouse Pests• Mites• Thrips• Aphids• Whiteflies• Mealybugs• Fungus gnats• Shore flies• Others…

Melon or cotton aphid

Aphid identification Pear shaped body

Cornicles = “tailpipes”

Most common species

Melon or cotton aphid

Potato aphid

Joseph Berger

Green peach aphid

Whitney Cranshaw

>135 plant families

>90 plant families

>125 plant families

Aphid Biology High reproductive rate

– 100 live young/female

– Asexual

– Live birth

– Life cycle 7-10 days

Remove sap

Produce honeydew

Aphid Damage

• Stunt plants

• Curling, cupping of

leaves

• Sticky honeydew

– Sooty mold

• Transmit viruses

Aphids: Monitoring

Scouting

Insects on stems,

fresh growth, under

leaves

Sticky honeydew on

leaf surface

Yellow cards: caution!

Most aphids don’t have wings!

Aphid Management

• Avoid excess Nitrogen

Whitney Cranshaw

Common Greenhouse Pests• Mites• Thrips• Aphids• Whiteflies• Mealybugs• Fungus gnats• Shore flies• Others…

Whitefly IdentificationGreenhouse

Trialeurodes vaporariorumSweet potato or Silver leaf

Bemisia tabaci

Photo credit: Gaucho

Ronald SmithUGA857007

Banded wingedTrialeurodes abutiloneus

Whitefly IdentificationGreenhouse

Trialeurodes vaporariorumSweet potato or Silver leaf

Bemisia tabaci

Whitefly Biology

All stages under leaf

Sedentary immatures

Life cycle in 1 month

Highly visible

MANY host plants

Greenhouse whitefly

Whitefly Damage

Yellowing and discoloration

Stunt plants

Honeydew and mold

Virus transmission

Whiteflies: Monitoring

– yellow cards

–plant inspection

• Undersides of leaves

• Honeydew

• Sooty mold

• Shake plant for adults

Sweet Potato Whitefly

Whiteflies: Management Cultural control

Plant-free periods

Time depends on

temperature

->cooler temps,

keep plant-free

longer

Common Greenhouse Pests• Mites• Thrips• Aphids• Whiteflies• Mealybugs• Fungus gnats• Shore flies• Others…

Mealybugs

“Big”: ¼ inch

Waxy, cottony, fringed

Sucking insects

– produce honeydew

– stunt plants

Attack all parts of plant

Life cycle: 1 month

Reduce marketability

Mealybugs: Monitoring

Scouting White flecks on

midribs, leaf axils, leaf

underside

Honeydew and sooty

mold

Common Greenhouse Pests• Mites• Thrips• Aphids• Whiteflies• Mealybugs• Fungus gnats• Shore flies• Others…

Fungus Gnats

Small, delicate flies

Feed on root, stems,

decaying debris

Need damp media

Life cycle 1 month

May promote diseases

– Pythium, Verticillium, Botrytis

Watch pet (wet) plants !

Fungus Gnats: Monitoring

Yellow cards Horizontal orientation

Potato disks

http://www.omafra.gov.on.ca/english/crops/facts/06-079.htm

Fungus Gnats: Management

Cultural control Less water!

Remove standing water

Sterilize/contain compost

Common Greenhouse Pests• Mites• Thrips• Aphids• Whiteflies• Mealybugs• Fungus gnats• Shore flies• Others…

Shore Flies

• Small, robust flies

• Feed on algae

• Must have damp media

• Leave frass on plants

• May move Pythium

spores

Shore Flies: Management

• Cultural Control

– Eliminate algae

Build an IPM Monitoring Program• Start simple• Careful inspection• Scout at least once per week• Designate pest management units (PMU)• Have some prior knowledge of problems• Keep good written records (database)

Thresholds

• Why use them?– Help maintain pesticide efficacy– Reduce disruption of cultural practices– Minimize phytotoxicity– Increase profit

• How to establish thresholds– From research– Systematic monitoring, historic records– Experiment

Greenhouse Insecticides/Miticides

• Food crops vs. ornamentals• Read labels carefully• Must have crop on label and no greenhouse

restrictions• Crop safety (new plant types/chemicals)

• Prefer selective materials– More compatible with biocontrol

Active Ingredients• pyriproyfen: Distance/Distance• spiromesofen: Judo/Oberon• spirotetramat: Kontos/Movento• pyridaben: Sanmite/Nexter• acetamiprid: Tristar/Assail• thiamthoxam: Flagship/Platinum• abbamectin: Avid/AgriMek• pymethozine: Endeavour/Fulfill• dinotefuran: Safari/Venom• imidacloprid: Marathon II/Admire

Ornamental formulation/ Vegetable formulation

Ornamental Products with Vegetable Uses

• Tristar (acetamiprid): Some transplants• Kontos (spirotetramat): Some transplants• Distance (pyriproxyfen): Tomatoes• Talus (buprofezin): Tomatoes• Pylon (chlofenapyr): Fruiting vegetables• Floramite (bifenazate): Tomatoes• Tetrasan (etoxazole): Tomatoes

Vegetable insecticides/miticides

Without GH restriction• Sevin• Malathion• Orthene• Mustang max• Pounce• Baythroid• Asana XL• Proaxis• Danitol• Warrior

Without GH restriction• Admire• Belay• Venom• Distance/Knack• Fulfill• Dipel• Courier• Agri-Mek• Acramite

These can be used in the greenhouse so long as the crop is on the label

Prohibited Vegetable InsecticidesWith GH prohibition• Diazinon• Endosulfan• Assail• Platinum/Actara• Radiant• Proclaim• Beleaf• Rimon• Intrepid

With GH prohibition• Avaunt• Oberon• Movento• Coragen• Portal• Belt/Synapse

Systemics for Ornamentals

Product Systemic Target pests IRAC Class

Marathon II Yes (↑) Aphids, WF, soft scale, fungus gnats, leafminers 4A

Flagship 25WG Yes (↑) Aphids, WF, fungus gnats, leafminers 4A

Safari 20 SG Yes (↑) WF, mealybugs, aphids, soft scale, fungus gnats, leafminers, armored scale

4A

Kontos Yes(↑↓) WF, mealybugs, aphids, soft scale, leafhoppers, scale crawlers(vegetable transplants: Fruiting and leafy)

23

Tristar 30 SG No WF, mealybugs, aphids, leafhoppers, thrips, leafminers, scale(Vegetable transplants: Fruiting, leafy, cucurbit, cole, and bulb)

4A

IGR Foliar Sprays for Ornamentals

Product Type Target pests IRAC Class

Distance 0.86EC IGR WF, scale, fungus gnats, shoreflies(Greenhouse tomatoes (>1”), bell pepper, eggplant)

7D

Talus 40 SC IGR WF, mealybug, leafhoppers, scale crawlers(Greenhouse tomatoes)

16

Pedestal 0.83EC IGR WF, thrips, caterpillars, leafminers 15

Ornazin 3% EC IGR WF supression, many other pest groups(brassica crops, cucurbits, eggplants, herbs and spices, legumes, peppers, tomatoes, and other miscellaneous crops grown in greenhouses)

UN

Foliar Sprays for Ornamentals

Product AI Pests targeted IRAC class

Aria 50SG flonicamid Aphids, WF, leafhoppers, mealybugs, scale stink bugs

9C

Conserve 1SC spinosad Caterpillars, thrips, leafminers 5

Decathlon 20 WP cyfluthrin Thrips, beetles, caterpillars * 3A*

TalstarOne 0.67 EC bifenthrin Thrips, beetles, caterpillars, plant bug, broad mites *

3A*

Tame 2.4EC fenpropathrin Thrips, beetles, caterpillars, plant bugs* 3A*

Hachi-Hachi tolfenpyrad Thrips, aphids, scale, leafhoppers, whitefly, caterpillars

21A

Pylon chlofenapyr Spider mites, broad mite, rust mites, cyclamen mite, beet armyworm, loopers, thrips, caterpillars(greenhouse fruiting vegetables 0-PHI)

13

Endeavor 50 WDG pymetrozine WF, aphids 9B

Mavrik Aquaflow Tau-fluvalinate Aphids, WF, mites, thrips, caterpillars 3A*

Mesurol 75W methiocarb Thrips, slugs, snails 1A

Miticides for OrnamentalsProduct AI Mites/Pests targeted IRAC Class

Akari 5SC fenpyroximate Spider mites, broad mites, cyclamen mites, rust mites, WF, mealybugs

21A

Judo 4SC spiromesifen Spider mites, broad mites, cyclamen mites, rust mites, WF

23

Avid 0.15EC abamectin Spider mites, broad mites, cyclamen mites, rust mites, WF, aphids, thrips, leafminers

6

Floramite 2 SC bifenazate Spider mites(greenhouse tomatoes)

UN

Shuttle O Acequinocyl Spider mites 20B

Tetrasan 5 WDG Etoxazole Spider mites(greenhouse tomatoes)

10B

Ultiflor Milbamectin Spider mites 6

Pylon chlofenapyr Spider mites, broad mites, cyclamen mites, rust mites

13

Ovation Clofentezine Spider mites 10A

Sanmite pyridaben Spider mites, broad mite, WF 21A

Hexygon Hexythiazox Spider mites 10A

Ornamental Insects - Chemigation

• Products that allow for some chemigation uses– Marathon II– Flagship– Safari– Kontos– Conserve– Ornazin

-- Sevin-- malathion-- Mustang Max-- Pounce-- Baythroid-- Asana XL-- Proaxis

-- Warrior-- Admire-- Venom-- Dipel

Resistance Management

• Only treat if needed• Rotate to a different IRAC class with each pest

generation• Do not tank mix products in the same

chemical class• Utilize biological control