Garden Pests - notes

1/7/2013

Out of the Wilds and Into Your Garden Pests, Pests, Pests

C.M. Vadheim and T. Drake
CSUDH & Madrona Marsh Preserve

Madrona Marsh Preserve
Gardening with Western L.A. County Native Plants March 7 & 10, 2009
Project SOUND - 2009
© Project SOUND © Project SOUND

What is a pest?  An organism which has Predator/prey relationships in nature
characteristics that are
regarded by humans as
injurious or unwanted
 Eats a desired plant
 Causes disease in a desired
plant
 Carries disease to a desired
plant
 May be:
 A vertebrate (deer; rabbit)
 An insect/mollusk (snail)
 A bacterium, virus or fungus
 A pest in one setting may be
beneficial in another; like a
weed, a pest may be an
organism ‘in the wrong place’
http://www.champaignschools.org/science/images/foodweb.gif

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In nature, plants fight back… A recipe for disaster
 Native plants evolved
with insects, other  Plant species not native to
animals, microorganisms area; often ‘cultivars’
– ecosystems in balance
 Some produce  Planted in mono-culture
noxious chemicals or
physical barriers to http://jenmill.blogspot.com/2006_04_01_archive.html  Heavily watered &
‘ward off’ natural fertilized – ‘plants on
pests steroids’
 Some attract  Using overhead watering
‘helper species’ –
insects & even birds
during warm summer days
 Some simply
tolerate normal
levels of predation  Globalization of pests
http://farm2.static.flickr.com/1118/814174806_a1348ae709.jpg


The ‘Old California Garden’ requires an
arsenal of ammunition…
And the consequences are not pretty…
 Human/animal health
risks
 Contaminated soils &
http://www.mindfully.org/Pesticide/2002/Flawed-Frogs-Pesticide-Deformed9jul02.htm water (including street
http://www.improvementscatalog.com/home/improvements water runoff)
/792923315-spray-doc-wheel-garden-sprayers.html

 High cost of pesticides
 Beneficial species killed
Issues:
 Improper use  Effects on animals up
the food chain
 Overuse
 Pesticide resistance
 Storage
http://grapes.msu.edu/images/pesticResist.gif

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Many of us have found that just including more
The ‘New California Garden’ is based on native species improves the ‘pest problems’ in the
a better strategy entire garden
 Plant the plants that are ‘programmed’ to be successful in your
area – these will:
 Be less stressed – and therefore healthier
 Be prepared to ‘fight’ the natural enemies
 Attract natural ‘helpers’ in their fight against pests

 Plant a variety of species – more like a natural ecosystem (not a
monoculture)
 Give the plants the appropriate gardening care:
 Appropriate levels of water
 Appropriate (often little to no) fertilizer
 Protection from other stress & injury

 Have an appropriate strategy to deal with true pests


But you need to have a sound strategy to
dealing with certain pests…even on
native plants Integrated Pest Management (IPM)

 "Optimum combination of control methods
including biological, cultural, mechanical,
physical and/or chemical controls to reduce
pest populations to an economical
acceptable level with as few harmful
effects as possible on the environment and
nontarget organisms."
R.L. Hix,CA Agric. Magazine, 55:4 (2001)
And that’s where the concept of Integrated Pest
Management (IPM) provides useful guidelines

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The IPM Pyramid – ‘first do no harm’
What is Integrated Pest Management?  Use the least invasive – and
often most effective - means
first:
 IPM programs use current, comprehensive  Prevention – cultural practices
 Mechanical Controls
information on the life cycles of pests and their
 Naturally occurring biological
interaction with the environment. controls (native predators)
 Consider using non-native
 This information, in combination with available predators
pest control methods, is used to manage pest  Use chemical controls sparingly,
damage by the most economical means, and with http://www.team.ars.usda.gov/ipm.html
as a last resort:
 Naturally occurring elements
the least possible hazard to people, property, and  Biologics – chemicals made by
the environment.’ Non-native predators and chemical plants that are toxic to
controls have the important drawback of pests/diseases
non-specificity – they kill the good pests  Non-biologic pesticides:
http://www.epa.gov/opp00001/factsheets/ipm.htm with the bad.  Insecticides
 Fungicides
 Miticides

An IPM system is designed around six
Some of the benefits of an integrated basic components
approach are as follows:
1. Set Action Thresholds
 Before taking any pest control action, IPM first sets an action
 Promotes natural controls; ‘ecosystem approach’. threshold, a point at which pest populations or environmental
conditions indicate that pest control action must be taken. Sighting
 Protects human health. a single pest does not always mean control is needed. The level at
which pests will either become an economic threat is critical to
guide future pest control decisions.
 Minimizes negative impacts to non-target
organisms. 2. Monitor and Identify Pests
 Not all insects, weeds, and other living organisms require control.
Many organisms are innocuous, and some are even beneficial. IPM
 Enhances the general environment. programs work to monitor for pests and identify them accurately,
so that appropriate control decisions can be made in conjunction
with action thresholds. This monitoring and identification removes
 Is most likely to produce long-term, beneficial the possibility that pesticides will be used when they are not really
results. needed or that the wrong kind of pesticide will be used.
3. Preventive Cultural Practices
 Often is easily and efficiently implemented.  As a first line of pest control, IPM programs work to manage the
crop, lawn, or indoor space to prevent pests from becoming a
 Cost-effective in the short and long-term. threat. These control methods can be very effective and cost-
efficient and present little to no risk to people or the environment.

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An IPM system is designed around six IPM plan for your garden – a work in
basic components progress

4. Mechanical controls: Should a pest reach an unacceptable level,
 Requires observation &
mechanical methods are the first options to consider. They knowledge – specific for
include simple hand-picking, erecting insect barriers, using traps,
vacuuming, and tillage to disrupt breeding.
your garden
5. Biological controls: Natural biological processes and materials can  Will vary somewhat with:
provide control, with minimal environmental impact, and often at
low cost. The main focus here is on promoting beneficial insects  Yearly weather conditions
that eat target pests. Biological insecticides, derived from  Maturity of plants
naturally occurring microorganisms (e.g.: Bt, entomopathogenic http://www.hoodcountymastergardeners.org/Demo_2006/Demo_Construction.html

fungi and entomopathogenic nematodes), also fit in this category.  New plants

6. Chemical controls: Synthetic pesticides are generally only used  Will be modified based on
as required and often only at specific times in a pests life cycle. your previous experiences
Many of the newer pesticide groups are derived from plants or
naturally occurring substances (e.g.: nicotine, pyrethrum and  Suggestion: keep a garden
insect juvenile hormone analogues), and further 'biology-based'
or 'ecological' techniques are under evaluation. notebook/journal

Many resources to help you University of California
Statewide IPM Project (UCIPM)
 Books – check out your  Goals of the IPM Project are to:
local library, or add to your  reduce the pesticide load in the
own environment,
 increase the predictability and
 On-line resources thereby the effectiveness of pest
control techniques,
 develop pest control programs that
 County Master Gardeners are economically, environmentally and
socially acceptable,
 Other Governmental  marshal agencies and disciplines into
resources: (see list) integrated pest management
program, and
 U.S.  increase the utilization of natural
 State & Local pest controls.
 Educational component:
 Print & on-line resources
 UC IPM Pesticide Education Program

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Set Acceptable Pest Levels
Monitor & Identify Pests
 Find out what pests/  Base monitoring on garden
conditions: temperature &
diseases occur in your humidity
garden – observation  Look for pests on vulnerable
tissues
 Learn more about the pests,  Shake out the pests, then view
with magnifying glass
their effects  Decide if action is needed
http://waterroots.com/imagespests/whitefly03.jpg  What are their life-stages  Suggestion: keep a log of dates,
 What seasons/conditions are conditions in your garden journal
they associated with
 What plant species are
susceptible

 Learn how to determine
when action should be taken
http://www.ctahr.hawaii.edu/noni/spiralling%20whitefly.asp


Prevention/Cultural Practices are the first
Criteria for selecting a treatment
line of defense against pests
strategy are:
 Cultural practices: just good old garden management
practices
1. Least hazardous to human health
 Providing alternate hosts for pests
 No monoculture 2. Least disruptive of natural controls
 Preventing over-wintering
 Sanitation
3. Least toxic to non-target organisms
 Proper water & nutrient management 4. Most likely to be permanent
 Correct watering
 Physical barriers 5. Easiest to carry out safely and effectively
 Pruning to improve air circulation
 Weeding 6. Most cost-effective
 Mulching
7. Most site-appropriate


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Pest challenges vary with the season…. Sticky (Bush) Monkey Flower -
Mimulus/Diplacus aurantiacus
 Warmer weather & new growth
– spring/early summer
 Sucking insects
 Chewing insects
 Gall & Blister Mites

 Warm weather – summer/fall
 Foliage fungal diseases
 Borers (insects) Scarlet Monkeyflower
 Root/stem rots Musk Monkeyflower
(fungal/bacterial)

 Cool, wet weather –
winter/early spring
 Mollusks
 Anthracnose (fungal)

http://www.baynatives.com/plants/Mimulus-aurantiacus/


Sucking insects
Any perennial or shrub/tree with fresh
 Definition: Insects that insert their mouthparts
into the sugary phloem (conducting tissue) & suck new foliage can attract sucking insects
the ‘sap’
 Examples:
 Aphids
 Mealy Bugs
 Whiteflies
 Psyllids
 Scales
 Leafhoppers
 Damage:
 Often confined to the young, succulent
growth (leaves, shoot-tips and buds
 Tissues appear puckered or crinkled
 Monitoring: watch for:
 Signs of the insects themselves –check
particularly undersides of leaves, other
protected areas
 Ants – tend to be ‘nurse’ species
 Abnormal plant growth
http://scienceblogs.com/neurophilosophy/Ant_cultivating_aphids.jpg © Project SOUND © Project SOUND

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Aphids: where there’s one there are many….. Aphids – Ugly but not usually murderers...

 Often called plant lice, are small,  Preventive cultural
soft-bodied insects. practices:
 Control ants
 They range in color from black to http://pmo.umext.maine.
 Control weeds –
green to yellow.
edu/factsht/Suck.htm

particularly Brassica
species
 Their numbers may greatly
increase in a short time and  Mechanical Controls:
crowding stimulates the  Blast off with a stream of
production of winged forms. water
 Use sticky strips around
 They may cover the entire trunks to manage ants
surface of a leaf or stem.
 Biological Controls:
 They (and other sucking pests)  Lady bugs; Lacewings
can be vectors of plant viruses
(crop & ornamental plants).  Chemical controls:
 Insecticidal Soap is usually
 They can also weaken plants, adequate
making them susceptible to other
diseases
http://ipm.ncsu.edu/cotton/insectcorner/photos/aphid.htm
http://notexactlyrocketscience.files.wordpress.com/2006/08/aphid-sap.jpg

Whiteflies Monitor particularly on citrus and
 Monitoring: vegetable crops (and plants near them)
 By placing yellow sticky cards in greenhouse &
other vulnerable environments
 Periodic inspection of undersides of leaves of
susceptible species
 Preventive cultural practices:
 Don’t purchase infested plants
 Control ants
 Encourage natural predators
 Mechanical Controls:
 Yellow sticky traps (early in infestation)
 Blast off with stream of water
http://ipm.ncsu.edu/cotton/InsectCorner/photos/other.htm  Hand-remove infested leaves
 Vacuum them up with hand vacuum Ash Whitefly (Siphoninus phillyreae)
 Biological Controls: http://cekern.ucdavis.edu/Entomology/Woolly_Whitefly_Monitoring_in_Kern_Cou
nty.htm
can attack Toyon & other natives
 Ladybugs, Lacewings, parasitic wasps & mites
Wooly Whitefly on Citrus
 Songbirds
 Chemical controls:
 Insecticidal Soap
 Chemical pesticides usually not very helpful –  Mechanical methods and encouraging natural enemies offer best
resistance quickly develops chance for control
http://agriculture.gov.bb/media/plant_protection/Whiteflies2.JPG

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 Females feed on plant sap, normally in roots or
other crevices. They secrete a powdery wax
Controlling aphids, whiteflies & Mealybugs is an
Mealybugs layer (therefore the name mealybug) used for important ‘cultural practice’ for preventing other diseases
protection while they suck the plant juices.
 Monitoring:
 Check stem axils & bottoms of plant stems for
insects  Mealybugs are similar to
 Act immediately when you see them to control whiteflies and aphids: they
infestation produce large amounts of
waste product (honeydew)
 Preventive cultural practices: which coats plants and
 Insect new plants – remove pests surrounding surfaces.
 Control ants (which protect Mealybugs)
 Encourage natural predators  This sticky layer is a perfect
 Mechanical Controls:
growth medium for a black
 Remove by hand & destroy
Sooty Mold fungus commonly known as
 Apply rubbing alcohol with a Q-tip or cotton
"sooty mold".
ball; destroys insects & egg masses [note: try
on small area first – may damage plant]  This mold damages plants by
covering leaves and reducing
 Biological Controls: light available for
 Lady Bug, Lacewings, parasitic wasps –all natural photosynthesis.
 Chemical controls:
 Insecticidal Soap or horticultural oils

Good natural enemies are there – just
True Bugs plant species that will attract them
 Many are actually beneficial
predators  Green Lacewing
http://pmo.umext.maine.edu/factsht/Suck.htm

 Common generalist predator
 Preventive cultural practices:  Kills: mealybugs, psyllids, thrips,
 Encourage healthy plants mites, whiteflies, aphids, small
caterpillars, leafhoppers, and
Green Lacewing
insect eggs
 Chemical controls: not
recommended in most cases  Use common pesticides & you’ll kill
this beneficial insect
You will need to learn about
 Plant species in the Rose &
Milkweed Bug
the common beneficial
insects in order to recognize Buckthorn (Ceanothus) families to
and attract them provide food for Lacewings


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Attract
Know all life phases of
these By planting
beneficial these species beneficial insects
insects
Bigeyed bug Native grasses  Don’t use pesticides that will kill the
Polygonum sp. (Silver Lace Vine) beneficial insects
Copyright © 2007 Ron Hemberger

Hoverflies Achillea sp. (Yarrow)  Larval stage – though ugly - is often the
Asclepias fascicularis (Narrowleaf Milkweed) ‘eating’ stage
Baccharis sp. (Coyote brush, Mulefat) http://www.ipm.ucdavis.edu/PMG/NE/convergent_lady_beetle.html

Ceanothus sp. (California Lilac)  Look closely at the insects (use a
Eriogonum sp. (Buckwheat) magnifying glass) – what are they eating
Prunis ilicifolia (Hollyleaf Cherry) (plant or insect)

Ceanothus sp. (California Lilac)
Lacewings
Prunus ilicifolia (Hollyleaf Cherry)
Lady beetles Achillea sp. (Yarrow)
Asclepias fascicularis (Narrowleaf Milkweed)
Atriplex sp. (Quailbush, Saltbush)
Ceanothus sp. (California Lilac)
Native grasses
Rhamnus californica (Coffeeberry)
Salix sp. (Willow)

http://www.ipm.ucdavis.edu/PMG/NE/brown_lacewing.html
http://www.stopwaste.org/home/index.asp?page=402 http://upload.wikimedia.org/wikipedia/commons/2/2a/Sa_lady-beetle-larva.jpg
http://www.kunafin.com/lacewings.htm © Project SOUND © Project SOUND
Lacewing Life Cycle

Attract
these By planting
Western Yarrow – Achilla millefolia
beneficial these species
insects
Minute Achillea sp. (Yarrow)
pirate bug Baccharis sp. (Coyote brush, Mulefat)
Eriogonum sp. (Buckwheat)
http://www.ipm.ucdavis.edu/PMG/NE/minute_pirate_bug.html

Minute Pirate Bug

Achillea sp. (Yarrow)
Parasitic & Aesclepias fascicularis (Narrowleaf
Predatory Milkweed)
Wasps Eriogonum sp. (Buckwheat)

Tachnid flies Achillea sp. (Yarrow)
Eriogonum sp. (Buckwheat)
Heteromeles arbutifolia (Toyon)

Rhamnus californica (Coffeeberry)

http://www.ipm.ucdavis.edu/PMG/NE/tachinid_flies.html

Tachnid Fly http://www.stopwaste.org/home/index.asp?page=402
J.S. Peterson @ USDA-NRCS PLANTS Database

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Why Yarrow makes a good lawn substitute Levels of Control
1. Cultural control is a preventative measure using fertilization,
plant selection, and sanitation to exclude problematic pests
 Spreads quickly, giving good and weeds.
cover 2. Physical control is another preventative strategy. It includes,
pest exclusion; creating barriers; modifying conditions such
 Super for banks and other areas as temperature, light and humidity; trapping; and manually
that can’t easily be mowed weeding. Foods and beverages should be eaten and stored
only in designated areas.
 Spreading habit inhibits weeds
3. Biological control makes use of a pest's natural enemies. This
 Can be mowed – occasionally and strategy introduces beneficial insects or bacteria to the
on high setting w/ rotary mower environment or, if they already exist, provides them with the
necessary food and shelter and avoids using broad-spectrum
 Companion plant – attracts chemicals that will inadvertently kill them.
beneficial insects, repels others
4. Chemical control is used after all other control strategies are
 Does well on poor, dry, sandy deemed inappropriate or ineffective. Target-specific, low-
soils where other plants grow toxicity pesticides should be applied in a manner that will
poorly maximize the effectiveness of pest management and minimize
the exposure to humans and other non-target species. Spot
treat if possible to reduce exposure.
http://www.dgsgardening.btinternet.co.uk/yarrow.JPG


Smothering and suffocation agents - mild Smothering and suffocation agents - mild
 Insecticidal Soap  Horticultural Oil
 It works on contact by breaking down
the target pest’s cuticle (waxy  Coating pests with horticultural oil
covering) — promoting dehydration and, blocks the passage of air through
ultimately, death. their spiracles (breathing holes),
 Short period of action (48 hours) thus killing (suffocating) them.
 Non-targeted – kills both beneficial
insects as well as pests  Used on dormant plants (see label
for specific product)
 Best use: judicious, small-scale spot
applications
 labeled for use against overwintering
 Safer’s Insecticidal Soap (the most eggs of European red spider mites,
common brand), is used indoors or out,
is effective on aphids, cabbageworms, http://greenmethods.com/site/products/biorationals/3/#ip
scale insects, apple aphids (not rosy
earwigs, flea beetles, lace bugs, aphids), bud moths, leafrollers, red
leafhoppers, mealybugs, psyllids, sawfly bugs, codling moth larvae, pear psylla
larvae, scale crawlers, squash bugs,
http://ecx.images-amazon.com/images/I/51z2EPV-efL._SL500_AA280_.jpg
thrips, spider mites, whiteflies, and (adults), blister mites, galls, whitefly
more. nymphs, and mealybugs.

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Sucking insects of spring/summer: review Ah, Summer….. the time of dusty leaves & over-watering

 Monitor
 Periods of new foliage/rapid growth
 Monitor at least weekly
 Look particularly at undersides of leaves, young branch tips, flower
buds – be sure to use a magnifying glass
 Cultural Practices
 Blast affected area with water
 Hand remove
 Encourage natural predators
 Control ants
 Biological Controls
 Beneficial insects – your best line of defense
 Chemical controls
 Not usually needed (except for very bad infestations – not often seen
with native plants)
 May kill beneficial insects – so use very sparingly
 Try least toxic: Insecticidal soap


Challenges of the dry season

 Dry, dusty foliage
 Hot, muggy (or foggy)
days
 Appropriate watering:
 How frequently
 How much at any one time
 How to water: overhead,
drip/trickle
 What time of day to water
The stage is set for a different
cast of garden pests

10 years old. Almost no water other than a dust wash off every month or so.
Arctostaphylos 'Carmel Sur’ in foreground, Toyon and Western Redbud behind.

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Toyon/California Christmas Berry –
Heteromeles arbutifolia Natives in the Rose Family (Rosaceae)
Shrubs
 Chamise - Adenostoma fasciculatum
 Mountain Mahogonies - Cercocarpus species
 Toyon - Heteromeles arbutifolia
 Creambush - Holodiscus discolor
 Ironwoods - Lyonothamnus floribundus
 Holly-Leafed & Catalina Cherries - Prunus ilicifolia
 CA Wild Rose - Rosa californica
 CA Blackberry - Rubus ursinus
Smaller perennials
 Pacific silverweed - Argentina egedii
 Strawberries - Fragaria species
 Wedgeleaf Horkelia - Horkelia cuneata


Common pests of Rose Family (think Leafhoppers & Sharpshooters
garden roses)  Pests of new foliage  Leafhoppers are small, green,
 Sucking insects
wedgeshaped insects that attack many
 Pests of summer garden, forage and fruit crops. They
 Pests associated with dust (mostly suck out plant juices causing yellowing,
insects) http://pmo.umext.maine.edu/factsht/Suck.htm
leaf-curling and stunting.
 Pests associated with warm, moist
conditions (mostly fungal but some
bacterial/viral)
 Leafhoppers are often responsible for
the spread of plant pathogens
 Diseases associated with cool, wet especially viruses and phytoplasmas
conditions:
 Fungal diseases (foliage & root)  Preventive cultural practices:
 Rosa CA vs. non-native roses  Mechanical Controls:
 It is relatively pest and disease free,
except if the plant is subject to  blast of water from a garden hose
overhead irrigation, poor air circulation  Removing infected lower leaves
and humid conditions in the shade.
 Insect pests are usually not a problem  Dusting plants lightly with
with such a hardy plant and with so diatomaceous earth
many “beneficials” around.

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Leafhoppers & Sharpshooters Glassy-winged Sharpshooter – reportable pest
 Biological Controls:  Carry the bacterium,
 Predatory insects such as mantids and Xylella fastidiosa, that
dragonflies causes Pierce’s Disease –
a serious threat to CA
 Spiders, green lacewings (Chrysopa spp.), grape industry
minute pirate bugs (Orius spp.), lady
beetles (Hippodamia spp.), and predaceous
mites.
Adults are about 1⁄2 inch long
 X. fastidiosa also causes
almond leaf scorch,
 Small parasitic wasps in the genus phoney peach disease,
Gonatocerus alfalfa dwarf, oleander
 Chemical controls: leaf scorch and citrus
variegated chlorosis.
 Narrow range oils, insecticidal soaps, or
kaolin clay
 Report to County Ag.
 rotenone, carbaryl, malathion or http://www.slocounty.ca.gov/Assets/AG/assets/GWSS2.gif
Service if found in new
methoxychlor areas


Tiny insects with fringed wings. They feed on
Pierce’s Disease: many native plants are Thrips 
pollen and tender plant tissue, rasping the
tissue and sucking the exuding sap.
alternate hosts
 The leaves take on a silvery appearance after
the thrips feed, and plants become stunted and
 Aesculus californica deformed.
 Artemisia douglasiana  Thrips are usually a pest of seedling plants but
 Heteromeles arbutifolia http://pmo.umext.maine.edu/factsht/Suck.htm may attack plants in any stage. They attack an
extremely wide variety of woody plants.
 Juglans californica
 Mimulus aurantiacus  Certain thrips species are beneficial predators
 Oenothera hookeri that feed only on mites and other insects
 Philadelphus lewisii  Monitoring:
 Populus fremontii  Thrips often feed within buds and furled leaves.
 Quercus spp. Their damage is often observed before the thrips
are seen.
 Rhammus californica  Discolored or distorted plant tissue or black
 Rosa californica specks of feces around stippled leaf surfaces are
clues that thrips are or were present.
 Salix spp.  Look carefully for the insects themselves before
 Sambucus spp. taking action. Severe infestation foliage looks
silver-spotted
 Vitis californica  Thrips are poor fliers but can readily spread long
distances by floating with the wind or being
transported on infested plants.
Blue Elderberry © Project SOUND © Project SOUND
http://mrec.ifas.ufl.edu/LSO/images/Thrips/ffa2-34.jpg
http://www.gardenseeker.com/plant_pests_problems/plant-pests/thrips_storm_flies.htm

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Thrips – mostly just ugly… Gall & Blister Mites: ugly but not killers
 Healthy woody plants usually tolerate thrips
damage; however, high infestations on certain
herbaceous ornamentals and developing fruits
or vegetables may justify control  Cause blistered leaves or galled
twigs on many landscape plants
http://chillithrips.tamu.edu/

 Practices to conserve natural predators; including alder, aspen, baccharis,
decrease dust, no pesticides beech, elm, grape, linden, maple,
 Pull weeds
 Prune and destroy infected branches and walnut
 Mechanical Controls: Live oak erineum mites  Monitoring:
 Blast of water from a garden hose
 Misshapen leaves
 Biological Controls:
http://virtual.clemson.edu/groups/hort/homeh
ort/images/thrips.jpg
 Many natural predators
 Remove damaged leaves
 Chemical controls: thrips activity does not
usually warrant the use of insecticide sprays  Mechanical Controls:
 Narrow-range oil, neem oil, pyrethrins combined
with piperonyl butoxide (Garden Safe Brand  Remove damaged leaves
Multi-purpose Garden Insect Killer, Spectracide
Garden Insect Killer)
 Malathion or rotenone only for severe problems

Toyon Thrips © Project SOUND Baccharis gall © Project SOUND

Spider Mites are tiny Spider Mites: prevention is best
 Not insects, but closely related to ticks and  Preventive cultural practices:
chiggers. They suck out juices from leaves  Wash dust off leaves in summer
and stems, causing plants to become  Don’t use insecticides (carbaryl (Sevin);
imidacloprid (Merit, Marathon) ) that kill natural
deformed or have a bronze or yellow predators; severe infestations often follow
appearance http://pmo.umext.maine.edu/factsht/Suck.htm insecticide use!
 Heavy infestations can cause leaf and bud  Mechanical Controls:
drop, serious stress and death of the plant.  blast of water from a garden hose
 1:1 mixture of alcohol and water [test on small area]
 Damaged areas typically appear marked with  Plant isolation
many small, light flecks – over slightly
cobwebby - giving the plant a somewhat  Biological Controls:
speckled appearance.  Small, dark-colored lady beetles known as the
"spider mite destroyers"
 Activity peaks during the warmer months;  Minute pirate bugs, big-eyed bugs (Geocoris
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7405.html
Dry, dusty conditions favor all spider mites species) and predatory thrips
 Parasitic spider Mites
 Monitoring:
 Chemical controls: not during hot weather or for
 Usually plant damage—stippling or yellowing of water stressed plants – test first on a few leaves
leaves Few insecticides are
 Insecticidal soap
 Look for webbing underneath leaves effective for spider
mites and many even  Horticultural oils (Sunspray)
 Shake mites onto paper & observe with hand aggravate problems  Sulfur
lens

15

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