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Top 10 Notorious Landscape Pests (and How to Deal With Them)
Daniel A. Potter, ProfessorUniversity of Kentucky
You
Insects
# 9 & 10 Web‐making Caterpillars
Eastern tent caterpillar
Fall webworm
Mimosa webworm
Non‐Chemical Control
Scrape off egg masses
Bag nests in small trees
Pole pruner
Tent Caterpillar outbreak of 2000‐2002
Mare Reproductive Loss Syndrome
Tent caterpillars can cause horse abortions
Remove cherry trees near pastures or paddocks
Tree injection
• Bidrin®
• Abacide 2®
• Tree‐age ®
Treated
Not Treated
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#8 BagwormsMajor Pest of Landscape Evergreens
Bagworms Behaving Badly
Female bagworm is wingless, legless; never leaves her bag
Adult male is a furry moth that emerges in late summer
Male Female lays eggs in her bag, where they overwinter
Male moths mate with female in late summer
Female
Eggs hatch, young bagworms begin feeding in May
Bagworm Control Tips
• Handpick bags with egg masses in winter or early spring and destroy
• Target small larvae with reduced‐risk insecticide in late May or June)
Pyrethroid sprays will control all defoliating pests
bifenthrin
lambda‐cyhalothrincyfluthrin
Reduced‐Risk Products for Defoliators
Bacillus thuringiensis: caterpillars only
Controls caterpillars, beetles, and sawfly larvae
Controls caterpillars and sawfly larvae
Must match the product to the target!
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#7 Sawfly Larvae
Sawfly: 6 or more pairs of fleshy abdominal “prolegs” (enough to spell SAWFLY)
No little hooks on prolegs
Caterpillar: 5 or fewer pairs with little hooks
Sawflies versus caterpillars
S A W F L Y
Red‐headed Pine Sawfly
European Pine Sawfly
Sawflies behaving badly
Sawfly pupal cases(present in winter) Sawfly adult
“Roseslug” – a Sawfly!
Controlling Sawflies
Effective sprays include:‐ Acelepryn®‐ Provaunt®‐ Pyrethroids
Or, prune out small infestations!
#6 Lacebugs, Leafminers, Psyllids
Boxwood psyllid
Boxwood leafminer
Azalea lace bug
Boxwood pests
Boxwood psyllid: cupped leaves
Boxwood leafminer
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Boxwood Pests Lay Eggs in Expanding Young Leaves in Spring
Boxwood Psyllid Boxwood Leafminer
Adult
Adult
Nymphs on new growth
Lace bugs
Nymphs on Cotoneaster Azalea Lace Bugs
Lace bugs damage many plants:
Sycamore OakHawthorn
Pyracantha, cotoneaster, andromeda Azalea
Systemics are the way to go for lace bug, leaf miner, and psyllid control!
#5 Mite Pests
Tiny: about the size of a period (.) of 12‐pt text
Eight legs
Leaf undersides
Stippling
Fine webbing
“Warm‐Season” Mites
“Cool‐Season” Mites
Twospotted spider mite Boxwood spider mite
Spruce spider mite Southern red mite Maple spider mite
European red mite
Spider Mite Symptoms
Stippled leaves
Bronzed or browned foliage
Mite damage to burning bush
Going…..
Going…….
Gone!
Beating foliage over paper to dislodge and detect mites
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Mite Control Tips:
Use a Miticide!
(Most insecticides won’t work for mites)
Good ones include:
Akari , Avid, Floramite, Forbid, Hexygon, Kontos, Promite, Pylon, Shuttle, Sanmite, TetraSan, Ultiflora
Neonicotoids can flare mite problems on woody landscape plants
‐ Stimulates mite egg‐laying‐ Kills natural predators
Haircut for Potter’s bug lectures
#4 Japanese Beetle
Adults active from mid‐June to mid‐August
Feed on >300 plant species!
Japanese Beetle Damage to Linden Tree, Lexington, KY, 2007
July 8July 18
Susceptible:
• Linden• Purple leaf plum• Purple sandcherry• Japanese maple• Certain crabapples• Roses
Resistant:
• Red maple• Dogwood• Redbud• Beech• Tuliptree• Sweet gum
Avoid Over‐planting Japanese Beetle‐Susceptible Species!
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Traps contain two lures: a floral scent, and the female sex pheromone
Trap placement was evaluated in 24 home landscapes
Test Plant
Trap
Traps often increase troubles with Japanese beetles!!
Japanese beetle adult control
• Acelepryn (4 weeks residual) • Pyrethroids
‐ Onyx (4 weeks)‐ Talstar (2‐3 wks)‐ Scimitar‐ Tempo
• Sevin (1‐2 weeks residual)• Systemics
# 3: Scale Insects
Armored Scales
Soft Scales
Armored Scales have a detachable, shell‐like cover made from shed skins and waxy secretions
Obscure scale on oak –an armored scale Covers flipped to
expose insects
Armored scales encrust branches or leaves; cause dieback and death of plant
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Some common armored scales
Obscure scale
Pine needle scale
Oystershell scale
Euonymus scale
Pine Needle Scale
Euonymus Scale
Dieback from Euonymus Scale
Soft Scales
Cottony maple scale
Magnolia scale Calico scale
Soft Scales
Soft scale damage:
• Sticky honeydew• Sooty mold • Crown thinning, dieback
Crawler Hatch
Scale Insect Control: Spring/Summer
• Monitor for crawler hatch
• Pyrethroids (Talstar, Scimitar, Tempo) effective if properly timed
Timing Scale Crawler Hatch by Plant Bloom:
Oystershell scale coincides with full bloom of Sargent crabapple
Euonymus scale coincides with 50% bloom of Kousadogwood
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Trunk injection Soil Treatment
Systemic Control for Scale Insects (variably effective):
Scale Control by Ant Exclusion Ants “tend” soft scales to get honeydew
They defend their “livestock” from predators
When ants were excluded….Predators reduced soft scales by 60‐80%!
Sticky band excludes ants
Predators gobble up the undefended scales
#2 Borers in trees and shrubs Some Borer‐Prone Woody Plants
Dogwood Recently transplanted or stressed hardwood trees
Ash
White birch
Flowering peach, cherry and plum
Lilac
Moth (“Clearwing”) borers
Lilac Borer
Dogwood borer
Peachtree and Lesser Peachtree borers
Banded ash borer
Clearwing borer larvae are whitish caterpillars with a brown head
Crown thinning
Cleawing Borer symptoms
Sawdust‐like frass expelled from cracks in bark
Pupal case of clearwing borer moth that has emerged
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Clearwing Borer Treatment Apply preventive bark spray (pyrethroid or Acelepryn) 1‐2 weeks after adults emerge
Residues intercept newly‐hatched larvae as they chew through bark
Treat main trunk to runoff
Timing Borer Control By Bloom of Indicator Plants:
• Lilac borer: Common lilac; full bloom
• Dogwood borer: Oakleaf hydrangea; first bloom
Flat‐headed Borers Adults are metallic‐colored beetles
Larvae flattened
Tunnels under bark girdle branches and trunk
Flat‐headed borers leave D‐shaped holes when adult emerges
Bronze Birch Borer:
Most destructive Insect Pest of White Birch
Flatheaded Appletree Borer:
Most destructive pest of maple trees in production nurseries
Flatheaded appletree borer also attacks many species of stressed landscape trees Crabapples, maples, hawthorn, dogwood, many others are susceptible
Newly transplanted trees Stressed trees
Flatheaded Appletree Borer:
Bark spray with Onyx in May prevents infestation of nursery liners
Systemic insecticides are effective against flat‐headed borers
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Managing wood borers:
• Minimize tree stress
• Avoid trunk wounds
• Plant well‐adaptedcultivars
# 1 Emerald Ash Borer Emerald Ash BorerToledo, Ohio, USA
Before (2006) After (2009)
Emerald Ash BorerAttacks & kills all sizes and species of ash
Bowling Green State University golf course
Ontario, Canada
Emerald Ash Borer Distribution: 2015
Suckering
D‐shaped holes
Diagnosing Emerald Ash Borer
Tunnels under bark
Thinning, dieback starting at top of tree
Not Treated
Systemic Treatments CAN Protect Trees from Emerald Ash Borer!
Treated
Tree can still be saved Too far gone to save
Rule of thumb: Under 30% canopy dieback, tree can be saved Systemic insecticides for
Emerald Ash Borer
2‐3 year’s protection 1 year protection
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MOST EFFECTIVE:Injection or Infusion with Tree‐Age™(Emamectin benzoate)
Several different delivery systems are available
Other systemic insecticide delivery techniques for emerald ash borer control
Soil drench
Soil injection
Lower trunk spray
www.emeraldashborer.info
You
Insects
You can access EntFacts through the University of Kentucky
Entomology web site
Turf & Landscape Entomology