Transcript Insect Pests in a GH

Insects and Related Pests in
the Greenhouse
Presented by Terry Ferriss, PhD
University of Wisconsin—River Falls
Common Pests in the Greenhouse
Aphids
Thripse
Fungus gnats
Shore flies
Whiteflies
Red spider mites
Cyclamen mites
Leafminer
Mealy bugs
Scales
Aphids

Description: 1/8” in size





black to green in color
winged and wingless
“tail-pipes”
“Y” shaped vein at wing tip
Location on plant:





Feeding:

piercing - sucking mouth

Found on entire plant
(growing tips to roots)
Primarily buds
Underside of leaves
Stems
Signs/Symptoms:



Distorted new growth /
chlorosis
Chlorotic pin-point spots on
older leaves
Honeydew and sooty mold
Honeydew and Sooty Mold
Aphids & many other insects frequently
excrete: Honeydew” --- shiny, sticky
Ants love to eat “honeydew”
Sooty mold grows vigorously on “honeydew”
Aphids (cont.)
Reproduction:

Female nymphs give birth to other
females without mating
Males and females appear outdoor as
winter approaches – mate



eggs overwinter
7 day life cycle possible !!!
Aphid’s Lifecycle
From: Nelson, Greenhouse Mgmt book
Aphid
From: Nelson, Greenhouse Mgmt book
Aphid damage to a
chrysanthemum
Controlling Aphids

Common crops:


impatiens, dahlia, cineraria , peppers, tomatoes
Management:







Avoid high N fertilization
wash aphids off plant
Aphidied parasitic wasp
Enstar (IGR)
Horticultural Oil
Orthene
Others …..
Thrips

Description: 1/32”-1/25”




Feeding:


Rasping - sucking mouth
Location on plant:


2 pairs of wings
dark brown / cigar shaped
may be confused with a speck of dirt on sticky card
in buds, in flowers, in leaf axils,
between bulb scales
Signs/symptoms:

White to silver feeding scars/streaks on new growth (turn tan to brown)
 Distorted or malformed foliage/flowers
 Stunted growth
 Carry virus (TSWV, INSV)
Thrips
Reproduction:
 Can complete in 2 weeks
 Warm or cool temps
 Pupates in soil
Thrips’s Lifecycle
From: Nelson, Greenhouse Mgmt book
Thrips
Thrips damage
Controlling Thrips

Common crops:


geraniums, chrysanthemums, impatiens
Management:




Build resistance to chemicals quickly
Sugar bait to increase exposure
CO2 = irritant and increases exposure
Contact chemicals: deliver as small particle size to reach thrips
hidden in leaf axils and buds.


(several including Marathon, Avid)
Biological control
Is it a fungus gnat or a shore fly???
Fungus gnat
Short fly
Resemblance
Tiny mosquito
Tiny fruit fly
Legs/antennae
Long
Short
Wings
Clear w/ a distrinct Y
shaped vein
Five light spots on
each gray wing
Food source
Plants, organic matter
in soil, fungi
algae
Fungus gnat vs. Shore fly
From: Nelson, Greenhouse Mgmt book
Fungus gnats

Description: 1/16”-1/8”



Location :



Larvae are in soil feeding on decaying OM
Adults do not feed but fly around plants and lay eggs in soil
Signs/symptoms:




adult looks like a tiny mosquito
larvae: worm-like white with black head (1/4 “)
Larvae can injure roots if high populations
Adults do not cause direct damage to the plant but can carry fungal
spores and are very undesirable.
Possible lack of vigor, chlorosis
Common crops: any plant in high organic media
Fungus gnat lifecycle (20 – 30 days)
From: Nelson, Greenhouse Mgmt book
Fungus gnat
From: Nelson, Greenhouse Mgmt book
Controlling Fungus gnats

Management:






Avoid algae in the area
Keep floors as dry as possible
Clean up spilled media
Eliminate weeds
BT (Bacillis thurengiensis)
Chemical options
Shore Fly
From: Nelson, Greenhouse Mgmt book
Shore Flies

Description: 1/8”


Location on plant:


No direct injury to plants, but shore flies may carry plant pathogens
Common crops:


Favor damp areas and algal growth
Signs/symptoms:


dark in color, looks like tiny fruit fly
Found on any crop around damp areas
Management:

Keep algae growth down, watch fertilizer and water runoff, chemical
and biological control
Shore Fly’s Lifecycle
From: Nelson, Greenhouse Mgmt book
Whiteflies

Description: 1/16”-1/8”





Location on plant:



Underside of leaves (10 young lvs)
fly when disturbed
Feeding:


wings covered with white waxy powder
yellow-orange body
Breed in oxalis and other weeds
Life cycle of 4-5 weeks
Piercing-sucking mouth part
Signs/symptoms:


Chlorosis
may leave honeydew
Whitefly’s Life cycle
From: Nelson, Greenhouse Mgmt book
Whitefly
From: Nelson, Greenhouse Mgmt book
Whiteflies (cont.)

Sweet potato WF vs Poinsettia WF
SPWF: moves slower / larger enstar /
flies further / grayer
PWF: reproduces 30% faster

Common crops: poinsettia, geranium,
tomato, pepper, fuschia
Controlling Whiteflies

Management:





Weed control
Enstar (IGR)
Encarsia formosa
Horticultural oil
Chemical control (in nymph or adult stage)
Marathon
 Pyrethrum
 others

Red Spider Mite
(2 –spotted red spider mite)

Description: .007”-.015”


Location on plant:


Underside of leaves and on flowers
Favorable conditions:


Red or orange in color
Low relative humidity and high temperatures
Signs/symptoms:



Chlorotic stippling on upper leaf surface
Yellow / bronzing of foliage – dry lvs
If severe will see webbing
cthr.hawaii.edu
Red Spider Mite Lifecycle
From: Nelson, Greenhouse Mgmt book
Red spider mite
Photo: NCSU
Photo: mumsanddahlias.com
gardenscure.com
Controlling Red Spider Mites

Common crops:


English ivy, marigold, foliage plants, ivy
geranium
Management:





Wash underside of leaves
Humidity / temp control
Parasitic mites
kenyon.edu
Biological sprays
Miticides effective only on adults
Cyclamen Mite


Description: .007”-.015”
Location on plant:


Signs/symptoms:



Distorted or stunted new growth,
blackened shoot tips
Common crops:


Growing tips
African violet, new guinea impatients, ivy, clematis
Management:

Rouge out infested plants, chemical control
Cyclamen Mite
From: Nelson, Greenhouse Mgmt book
Leafminer

Description: 1/16”,



stout bodied flies that are
black and may have a bright
yellow thorax
Location on plant:

High nitrogen levels
Signs/symptoms:



Leaves
Favorable conditions:


Common crops:


Punctured leaves where
females lay eggs
“Mines” through leaves after
eggs hatch
marigold, chrysanthemum,
petunia
Management:

Resistant varieties,
chemical/biological controls
Leafminer’s Lifecycle
From: Nelson, Greenhouse Mgmt book
Leafminer
Leafminer damage
From: Nelson, Greenhouse Mgmt book
Mealybug

Description: 1/8”-1/4”


Location on plant:


soft-bodied insect covered in a white, waxy secretion
Leaf axils, leaf midribs, underside of leaves
Signs/symptoms:




Honeydew on leaves,
leaf yellowing and leaf drop,
cottony white masses in leaf axils and underside of leaves,
new growth is distorted
Mealybug

Common crops:


Foliage plants
Signs / symptoms:




“spitballs” in leaf axils and
along veins
Stunted growth
Chlorosis of adjacent plant
parts
Feeding:


Piercing-sucking mouth part
Management:




Rouge out infested plants,
wash off plants,
chemical control (nymphs are
most susceptible),
biological control
Mealybug Lifecycle
Mealybug
From: Nelson, Greenhouse Mgmt book
Scales

Description: 2-5mm


soft and white to hard and
dark bodied
Signs/symptoms:



Feeding:

piercing sucking mouth

Common crops:


Location on plant:

Stem, flowers, fruits, roots,
crown

Silver streaking honeydew on
plant,
Chlorosis
woody interiorscape plants,
amaranthus
Management:


Destroy infested plants
chemical and biological
controls
Scales’s Lifecycle
From: Nelson, Greenhouse Mgmt book
Scales
University of Wisconsin—River Falls
Thank you
Terry Ferriss, PhD