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Trees & Shrubs

PestsDiseasesCultural Disorders
 
 
 

 

 

 

PESTS
Select the pest from the images below for more information:

AphdsAsh Bark BeetleAsh Leaf Cone CaterpillarAsh Plant Bug

 

 

 

 

 

Aspen LeafminerBirchleaf MinerBoxelder MidgeCankerworm

 

 

 

 

 

Cottony PsyllidDusky Birch SawflyElm Leaf MinerElm ScaleErineum Gall Mite

 

 

 

 

 

Europhid Mite on CranberryEurophid Mite on MapleHawthorn LacebugLeaf Cutter Bee

 

 

 

 

 

Leaf Rollers on AspenLeaf Tiers on AspenLilac Leaf MinerMaple Leafcutter MothOak Gall Mites

 

 

 

 

 

Oak Gall WaspOak MitesOak Phylloxera AphidPear SlugPoplar Borer

 

 

 

 

 

Poplar Willlow BorerScurfy ScaleSpider MitesStink Bug

 

 

 

 

 

Tent CaterpillarViburnum Leaf BeetleWillow Leaf Blotch MinerWooly Bear Caterpillar

 

 

 

 

 


Aphids
AphidsAphids

Plants affected:  Numerous indoor and outdoor plants

Symptoms:  Severe infestations will cause curling/twisting of foliage, flowers to wilt and drop.

Life Cycle:  Eggs hatch on host plants in spring, these nymphs give birth to ‘daughters’, within days the daughters give birth - up to 30 generations per summer

Cultural Control:
• Ladybird beetles/larvae, lacewings are natural predators
• Strong jet of water to knock aphids off plants

Chemical Control:
Doktor Doom House and Garden, End All, Ambush


Ash Bark Beetle

Ash Bark BeetleAsh Bark BeetlePlants Affected:  Ash

Symptoms:
• Wilting, yellowish foliage
• Check under bark for adults/galleries

Life Cycle:
• Adults overwinter in the bark of host trees
• In spring, females construct egg galleries (tunnels) between the bark and wood of host trees, which are typically stressed or damaged
• Larvae tunnel and feed in the inner bark of the tree during spring and summer
• Adults emerge in late summer
• One generation per year

Controls - Cultural or Non-chemical:
• Keep trees well-watered and fertilized
• Prune out dead or dying branches in early spring
• Remove old, badly infested trees

Controls - Chemical Controls:  Doktor Doom Residual (yellow can) – insert straw into galleries to apply insecticide


Ash Leaf Cone Caterpillar

Ash Leaf Cone CaterpillarAsh Leaf Cone CaterpillarPlants Affected: Ash

Symptoms - Leaves rolled into cones - damage cosmetic

Life Cycle:
• Adult moths emerge in spring to early summer, mate and lay eggs on the leaves, twigs or bark of host trees
• Larvae hatch and roll leaves into cones to protect themselves as they feed, a stage that lasts up to 2 months
• Pupae may overwinter in the bark of host trees, or drop to the ground
• Usually one generation per year

Controls - Cultural or Non-chemical:
-Parasitic wasp is helping control
-Handpick small infestations
-Good leaf cleanup in fall

Controls - Chemical:  None – spraying will kill beneficial insects that provide control


Ash Plant Bug

Ash Plant BugAsh Plant BugPlants Affected: Ash

Symptoms:
• Leaves turn yellow, may appear mottled or burned (similar to leaf hopper damage)
• Leaves may drop prematurely
• Damage is cosmetic

Life Cycle:
• Overwinter as eggs in the bark of ash trees
• In spring, eggs hatch and nymphs feed on the undersides of emerging leaves
• A second generation appears in July
• Adults are active from late summer until killing frost

Controls - Cultural or Non-chemical:
• Keep trees well-watered and fertilized, especially in droughts
• Remove feeding insects with a strong jet of water

Controls - Chemical:  Ambush


Aspen Leafminer

Aspen LeafminerAspen LeafminerPlants Affected: Swedish Columnar Aspen, Trembling Aspen, Poplar

Symptoms:
• Silvery “trails” appear on the upper surface of leaves
• Insects will be found inside the leaves
• Damage is cosmetic

Life Cycle:
• Adult moths overwinter in bark of host trees and surrounding duff layer
• Adults emerge in early spring, before bud break
• Tiny white moths can be seen in great numbers when active
• Moths feed on nectar secreted by emerging leaves, mate, and lay eggs on the upper surface of leaves
• 10-14 days later, larvae hatch and mine into the leaves, and begin feeding on the tissue between the epidermal layers
• 2 weeks later, larvae emerge from the leaves and pupate in a fold on the leaf edge
• Adults emerge in July; there is one generation per year

Controls – Cultural or Non-chemical:
• Keep trees well-watered and fertilized
• Remove all fallen leaves in fall
• For small infestations, hand-pick affected leaves

Controls – Chemical:  None available or necessary


Birch Leafminer

Birch LeafminerBirch LeafminerPlants Affected: Birch

Symptoms:
• Large dead patches (yellow/brown) in leaves
• Entire tree may appear to change to yellow or brown colour
• Insects will be found inside the leaves
• Damage is cosmetic

Life Cycle:
• Two generations per year
• Adult wasp emerges in late May
• Females insert eggs into leaves
• Larvae hatch and feed on the tissues between the leaves’ outer epidermal layers
• Mature larvae exit the leaves and drop to the ground to pupate, 1-2” deep
• Second generation hatches 2 weeks later; cycle repeats

Controls - Cultural or Non-chemical:
• Has been kept under control very well by beneficial insects
• Keep trees well-watered and fertilized, especially during drought

Controls - Chemical:  Not available or necessary


Boxelder Midge

Boxelder MidgeBoxelder MidgePlants Affected:  Boxelder, Manitoba Maple

Symptoms:
• Leaves curl tightly, open to reveal white larvae
• Damage is cosmetic

Life Cycle:
Adults emerge in spring when first leaves are unfurling
• Eggs are deposited into young folded leaves. Larvae appear a few days later and twisting/curling of foliage shortly after
• In mid-late June larvae drop to the ground, work their way into soil and construct cocoons. In late summer they pupate, overwinter in the soil

Controls - Cultural or Non-chemical:
• Prune off worst affected leaves (that can be reached), so less larvae drop to ground to pupate.  Problems are aesthetic, since less than 50% of the tree is usually affected

Controls - Chemical: None available or necessary


Cankerworm

CankerwormCankerworm DamagePlants Affected: Fruit Trees, Oak, Linden, Maple

Symptoms: Defoliation, sticky honeydew residue

Life Cycle:
• Spring Cankerworm - emerges as an adult in late March or early April, after overwintering as naked brown pupae about four inches under the group..  Eggs are laid, hatch and larvae start to feed
• Fall Cankerworm - in fall male/female mate, female lays eggs, larvae hatch in spring.  Larvae feed then drop to ground and burrow. They emerge again in fall to mate and lay eggs

Controls - Cultural or Non-chemical:
• Horticultural Oil can be applied in late fall and early spring
• Apply BTK from mid April until late May (3-4 applications throughout)

Controls – Chemical:  Not necessary


Cottony Psyllid

Cottony PsyllidCottony PsyllidPlants Affected: Ash, Elder (plants stressed by drought are more susceptible)

Symptoms:  Twisted, distorted foliage—eventually browns and drops

Life Cycle:
• Overwinters as eggs laid along edges of bud scales
• Eggs hatch in May/June

Controls – Cultural or Non-chemical:
• Insect is very difficult to control once feeding begins. After leaf drop in fall (while temps still above 0) spray branches with Horticultural Oil (use dormant application rate)
• Again in early spring once leaves are about 3” long (this is when eggs are mature) spray again with Horticultural Oil (use summer application rate)

Controls - Chemical:  You may spot adults dropping from tree on silken threads in late spring; if you notice these spray insects with Ambush


Dusky Birch Sawfly

Dusky Birch SawflyPlants affected: Birch

Symptoms:  Clusters of yellow worms with black spots seen feeding around edges of leaves

Life Cycle:  Pupae overwinter in soil; larvae emerge in spring and feed May to early July. A second generation may be seen in September

Controls – Cultural or Non-chemical:  Handpick larvae

Controls – Chemical: Ambush, Malathion


Elm Leaf Miner

Elm Leaf MinerElm Leaf MinerPlants Affected: Elm

Symptoms:
• Leaves develop dead brown patches
• Insects will be found inside the leaves
• Damage is cosmetic

Life Cycle:
• Overwinters as pupae in the soil
• Adult sawflies are active from early May to early June
• Females insert eggs into the leaves of host trees in spring
• Larvae feed on the tissue between the epidermal layers of the leaves
• Mature larvae emerge from the leaves in mid-July and drop to the ground to pupate
• One generation per year

Controls - Cultural or Non-chemical:
• Keep trees well-watered and fertilized
• With small infestations, handpicking mined leaves is effective
• Remove all fallen leaves in fall

Controls - Chemical:  None available or necessary


Elm ScaleElm Scale

Plants Affected: Elm

Symptoms:
• Honeydew, sooty mold on leaves and bark
• Branches die back
• Dark-coloured “bumps” noted on branches

Life cycle:
• Overwinter as eggs on the twigs of host plants
• Crawlers hatch in spring and disperse amongst suitable hosts by wind or animal carriers
• Mature scale mate; males then disappear and adult females become permanently stationary, developing an outer shell that protects them from harm
• By midsummer, adult females then begin to feed by sucking the sap from the host; eggs are laid beneath their bodies
• One generation per year

Controls - Cultural or Non-chemical:
• Apply a mixture of Horticultural Oil and Lime Sulphur in fall after leaves have dropped; reapply in early spring before new leaves emerge
• With small infestations, run gloved hand along bark to dislodge scales

Controls - Chemical:  Not available


Erineum Gall Mite (Velvet Mite)

Erineum Gall MitePlants Affected: Maple, Birch, Viburnum (Cranberry), Linden

Symptoms:
• Feeding by mites forms raised, velvety, whitish to pinkish patches on leaves
• Damage is cosmetic

Life Cycle:
• Adults overwinter in the bark of host plants
• Adults begin to feed on developing buds in spring, initiating gall development
• Female adults become encased in galls and lay eggs
• Young hatch and quickly mature and exit galls, repeating the cycle
• Several generations per year

Controls - Cultural or Non-chemical:
• Remove affected leaves
• Apply Horticultural Oil in fall after leaves drop; reapply in early spring before new leaves emerge

Controls - Chemical:  Not necessary or available


Eriophyid Mite on Cranberry

Europhid on CranberryPlants Affected: Cranberry/Viburnum

Symptoms:
• Leaves develop fuzzy white patches; commonly mistaken for powdery mildew
• Damage is cosmetic

Life Cycle:
• Adults overwinter in the bark of host plants
• Adults begin to feed on developing buds in spring, initiating gall development
• Female adults become encased in galls and lay eggs
• Young hatch and quickly mature and exit galls, repeating the cycle
• Several generations per year

Controls - Cultural or Non-chemical:
• Prune out affected sections as soon as damage noted
• Pick off affected leaves
• Apply Horticultural Oil after leaves drop in fall; reapply in early spring before new leaves emerge

Controls - Chemical:  Not necessary or available


Eriophyid Mite on Maple

Eriophyid Mite on MapleEriophyid Mite on MaplePlants Affected: Maple

Symptoms:
• Small, red, round “bumps” are seen on the surface of leaves in early to midsummer
• Damage is cosmetic

Life Cycle:
• Adults overwinter in the bark of host plants
• Adults begin to feed on developing buds in spring, initiating gall development
• Female adults become encased in galls and lay eggs
• Young hatch and quickly mature and exit galls, repeating the cycle
• Several generations per year

Controls - Cultural or Non-chemical:
• Prune out affected sections as soon as damage noted
• Pick off affected leaves
• Apply Horticultural Oil in fall after leaves drop; reapply in early spring before new leaves emerge

Controls - Chemical:  Not necessary or available


Hawthorn Lace Bug

Hawthorn Lace BugHawthorn Lace BugPlants affected:  Plants in the Rose Family, primarily Hawthorn, Pear, Cotoneaster, Saskatoon

Symptoms:
• Adults are small winged insects which appear to be covered in lace. Nymphs are dark brown to black and covered in varying amounts of spines
• Stippled or mottled leaves with many lace bugs present
• Feed in large numbers, leaves may be stained with their excrement

Life Cycle:
• Overwinter as adults (two generations per season)
• Black eggs are laid in clusters on the underside of leaves in early spring
• Nymphs emerge and feed on the underside of the leaves after about 3 weeks
• 5 instars; 1st generation of adults emerge in mid-summer, 2nd in fall

Controls – Cultural or Non-chemical:
• For small infestations, handpick
• Keep well-watered and fertilized

Controls – Chemical:
• For smaller shrubs, Doktor Doom House and Garden
• For larger shrubs or trees, Ambush


Leaf Cutter BeeLeaf Cutter BeeLeaf Cutter Bee

Plants Affected: Many, including Rose, Lilac, Ash

Symptoms:
• Half moon shapes cut out of leaves
• Use leaves to seal eggs into the cells of the hive
• Beneficial insect; may pollinate garden crops, do pollinate alfalfa
• Damage is cosmetic

Life Cycle:
• Overwinter as pupae in cells constructed out of leaf debris collected during spring and summer
• Adults emerge in spring and collect leaf material, pollen and nectar, and construct their cells
• Eggs are laid within the cells
• Larvae hatch and feed within the cells, and pupate before winter

Controls - Cultural or Non-chemical:  Pick off affected leaves if desired

Controls - Chemical:  Not necessary


Leaf Rollers on Aspen

Leaf Rollers on AspenLeaf Rollers on AspenPlants Affected: Aspen

Symptoms:
• Leaves rolled up tightly
• The culprit is a whitish caterpillar
• Cosmetic

Life Cycle:
• Overwinter as pupae in the soil and leaf debris on the ground
• Adult moths emerge in early spring and lay eggs on host trees
• Larvae hatch and construct shelters by rolling leaves up
• Mature larvae drop to the ground by late summer and pupate

Controls - Cultural or Non-chemical:
• Parasitic wasps help control
• Apply Horticultural Oil in early spring, before new leaves emerge

Controls - Chemical:  Not available


Leaf Tiers of Aspen

Leaf Tiers of AspenLeaf Tiers of AspenPlants Affected: Aspen

Symptoms:
• Leaves are tied together with silk and may be disfigured
• The culprit is a small green caterpillar
• Cosmetic

Life Cycle:
• Overwinter as eggs on the bark or twigs of host trees
• Larvae hatch in spring and feed from within two leaves they have tied together
• Adult moths are active from late summer to fall and lay eggs during this time

Controls - Cultural or Non-chemical:
• Parasitic wasps help control
• Apply Horticultural Oil in early spring, before new leaves emerge

Controls - Chemical:  Not available


Lilac Leaf Miner

Lilac Leaf MinerPlants Affected: Lilac

Symptoms:
• Olive green patches that later turn into brown, blotchy areas
• Damage is cosmetic

Life Cycle:
• Mature larvae overwinter in soil, awake in spring and pierce leaf, laying eggs in late May in the evening, in rows on undersides of leaves. Hatch within 7-10 days
• Larvae bore into leaf and feed between layers for about 3 weeks, then surface, roll up in leaves and feed again
• 10 days later drop to ground, pupate and emerge again in early August for the second generation. These will feed until mid September then overwinter in soil

Controls - Cultural or Non-chemical:
• Remove affected leaves as they are noticed
• Keep well-watered and fertilized

Controls - Chemical:  Not available


Maple Leafcutter Moth

Maple Leafcutter MothMaple Leafcutter MothMaple Leafcutter MothPlants Affected: Maple, Birch, Saskatoon

Symptoms:
• Oval holes cut out of leaves, to be used by insect to "shield" itself
• Damage is cosmetic

Life Cycle:
• Overwinters as pupa, emerges in spring to lay eggs as leaves unfurl
• Larvae feed as leafminers for a bit, then emerge from mine and create a shelter using disks they have cut from leaf.  As they mature they create bigger shelters using more disks from the leaf.  Drop to the ground in fall to overwinter

Controls - Cultural or Non-chemical:
• Rake and destroy affected leaves
• Apply BTK as larvae emerge from mines

Controls - Chemical:  Not available


Oak Gall Mites

Oak Gall MitesPlants affected: Oak

Symptoms:
• Irregular “bumps” appear on foliage
• Damage is cosmetic

Controls – Cultural or Non-chemical:
• For small infestations, handpick affected leaves
• Good fall cleanup
• Apply Horticultural Oil in early spring, before new leaves emerge

Life Cycle:
• Adults overwinter in the bark of host plants
• Adults begin to feed on developing buds in spring, initiating gall development
• Female adults become encased in galls and lay eggs
• Young hatch and quickly mature and exit galls, repeating the cycle
• Several generations per year

Controls – Chemical:  Not available


Oak Gall Wasp

Oak Gall WaspPlants Affected: Oak

Symptoms:  Round to oval galls about 1/2” in diameter found on twigs/branches in clusters. New galls are green, old ones brown

Life Cycle: Adult wasps lay eggs in leaf buds in fall. By early summer next season, larvae secrete chemical that causes plant tissue to enlarge (thereby creating gall). Gall envelops them. Late summer, adult emerges from the gall, mates and lays eggs again

Controls – Cultural/Non-chemical:
• Prune out galls
• Apply Horticultural Oil in early spring, before new leaves emerge
• Keep trees well-watered and fertilized

Controls – Chemical:  Not available


Oak Mite

Oak MitesPlants Affected: Oak

Symptoms:
• Small round shaped multi coloured galls appear like 'Fruit Loops' on backside of Oak leaves
• Damage is cosmetic

Life Cycle:
• Adults overwinter in the bark of host plants
• Adults begin to feed on developing buds in spring, initiating gall development
• Female adults become encased in galls and lay eggs
• Young hatch and quickly mature and exit galls, repeating the cycle
• Several generations per year

Controls - Cultural or Non-chemical:  Prune out affected portions when first noted

Controls - Chemical:  Not available


Oak Phylloxera Aphid

Oak Phylloxera AphidPlants Affected: Oak - mostly English Oak

Symptoms:  Yellow spots (“measles/chicken pox”) turn into dead spots in June. Turn leaf over, there will be a bright orange aphid

Life Cycle:
• Several generations per year
• Eggs overwinter in bark of host trees
• Nymphs hatch in spring and begin feeding on leaf undersides
• Mature aphids begin laying eggs in a circle around themselves, which will soon hatch into the next generation

Controls – Cultural/Non-chemical: Good fall cleanup

Controls – Chemical:  Not available


Pear Slug

Pear SlugPear SlugPlants Affected: Fruit Trees, Cotoneaster, Mountain Ash, Hawthorn

Symptoms:
• Browning and leaf skeletonizing in mid to late June and again late July/August
• Culprit is a small, dark-coloured, slug-like larva
• Damage is cosmetic

Life Cycle:
• Overwinter as pupae in leaf litter on the ground
• Adult flies emerge in late spring after hosts leaf out
• Females lay eggs into leaves, creating blisters
• 10-15 days later, slug-like larvae hatch and begin feeding on upper leaf surfaces
• Feeding continues for 2-3 weeks, skeletonizing leaves
• Mature larvae then drop to the ground to pupate
• A second generation emerges in late July; this causes the most damage

Controls - Cultural or Non-chemical:
• Pick off larvae, hose off with strong jet of water
• Bark mulch may deter adults’ emergence
• Parasitic wasps aid in control

Controls - Chemical:  Ambush for large infestations


Poplar Borer

Poplar BorerPoplar BorerPlants Affected: Aspen, Willow, Poplar

Symptoms:
• Varnish-like resin and holes with boring dust on the stems. Larval galleries under bark
• Prefers main stems
• Damage could be confused with Poplar/Willow Borer

Life Cycle:
• Adults emerge late June. Females cut crescent shaped marks in bark in which to lay eggs
• Eggs hatch, larvae mine into bark and stay for summer and winter. Next spring enter the heartwood of tree and feed for 2 years; this is when you’ll notice sap

Controls – Cultural/Non-chemical:
• Use heavy gauge wire; locate holes and stick wire in to pierce and kill larvae
• Keep trees well-watered and fertilized

Controls – Chemical:  Not available


Poplar/Willow Borer

Poplar Willow BorerPlants Affected: Willow, Aspen, Poplar

Symptoms:
• Upper crown or whole branches broken over and dead, through which red-brown or white shavings exude
• Piles of sawdust on the ground
• Prefers smaller branches
• Irregular splits and holes in bark of tree
• You’ll see more sawdust than sap (Poplar borer more sap)

Life Cycle:
• In summer, females chew holes in bark and lay eggs. Larvae burrow into upper bark first, then inner wood where they create meandering tunnels
• Previously injured trees will have circular emergence holes that have scabbed over

Controls - Cultural/Non-chemical:
• Use heavy gauge wire; locate holes and stick wire in to pierce and kill larvae
• Keep trees well-watered and fertilized

Controls – Chemical:  Not available


Scurfy Scale

Scurvy ScaleScurvy ScalePlants Affected: Mainly Cotoneaster and other members of the Rose Family; also Ash, Aspen, Dogwood, Willow

Symptoms:
• Clusters of whitish to brown “bumps” found along branches
• Mistaken for fireblight, kills twigs/branches

Life Cycle:
• Overwinter as eggs on the twigs of host plants
• Crawlers hatch in spring and disperse amongst suitable hosts by wind or animal carriers
• Mature scale mate; males then disappear and adult females become permanently stationary, developing an outer shell that protects them from harm
• By midsummer, adult females then begin to feed by sucking the sap from the host; eggs are laid beneath their bodies
• One generation per year

Controls - Cultural or Non-chemical:
• Prune out affected branches/stems (bad infestations on Cotoneaster may necessitate a full rejuvenation prune to ground level)
• Natural predators include lacewings and lady bugs
• Apply a mixture of Horticultural Oil and Lime Sulphur in fall after leaves drop; reapply in early spring before new leaves emerge (use at half strength on Cotoneaster)
• Keep well-watered and fertilized

Controls - Chemical:  Malathion at end of June


Spider Mites

Spider MitesPlants Affected: Numerous

Symptoms:
• Stippling—tiny dots in foliage
• Yellowing of foliage—’haze’ on foliage
• Foliage can turn completely brown in severe cases
• Fine webbing is also often observed in bad infestations

Life Cycle:
• Overwinter in diapause (hibernation); capable of surviving severe winters
• Adults emerging after winter lay up to 100 eggs each during their 2-week lifespan
• Maturation period varies from 5-25 days depending upon weather conditions (mature faster in hot, dry conditions)
• Mites are dispersed by wind and animal carriers
• There can be many generations per year

Controls - Cultural or Non-chemical:
• Repeat spraying of water on foliage – this can be done several times per week and is very effective at reducing the mites’ numbers
• Good fall cleanup
• Keep plants well-watered and fertilized

Controls - Chemical:  Doktor Doom Spider Mite Knockout for smaller shrubs; Safer’s End-All, Malathion for larger shrubs/trees


Stink Bugs

Stink BugsPlants Affected: Numerous

Description:
• Various forms/colours will be seen - will generally have a large triangular plate on their back
• Omit foul smelling substance when disturbed
• Does not generally cause noticeable damage to plants

Life Cycle: Adults overwinter in plant debris and in soil.  Emerge May - June, egg are laid in June/July, from egg to adult takes about 25 days

Controls:
• Though found in large numbers, rarely cause damage to the extent that warrants spraying insecticide
• They are actually a predator of the Colorado Potato Beetles, each nymph can consume over 250 eggs


Tent Caterpillar

Tent CaterpillarTent CaterpillarPlants affected: Mainly Aspen and Poplar; also Apple, Ash, Birch, Choke Cherry, Elm, Maple, Oak, Willow

Symptoms:
• Masses of relatively large, colourful caterpillars are found in spring, constructing “tents” of silk for shelter
• Causes major defoliation on host trees

Life Cycle:
• Several different species with similar life cycles
• One generation per year
• Adult moths lay eggs in summer, which overwinter in the crotches of trees
• Eggs hatch in spring; larvae feed for 4-8 weeks before maturing

Controls – Cultural/Non-chemical:
• Remove ‘tents’ - best done in late evening or early morning
• Handpick, scrape cocoons off of branches in summer
• Apply BTK while larvae are present; reapply as needed every 5-7 days

Controls – Chemical:  Not necessary; BTK very effective


Viburnum Leaf Beetle

Viburnum Leaf BeetleViburnum Leaf BeetlePlants Affected: Viburnum/Cranberry

Symptoms:
• Early damage appears as pin pricks—by June skeletonizing apparent
• In summer, lines of holes (egg chambers) can be seen along twigs of current season’s growth

Life Cycle:
• Eggs hatch in May, larvae begin feeding
• In June larvae drop to ground to pupate. Adult beetles emerge, females chew holes in twigs, lay eggs from summer to frost

Controls - Cultural/Non-chemical:  Early spring examine twigs for holes—prune out

Controls - Chemical:  Doktor Doom House and Garden—as leaves expand in spring, look for larvae and spray these. Adults difficult to spray as they fly away when disturbed


Willow Leaf Blotch Miner

Willow Leaf Blotch MinerPlants Affected:  Willow, especially Laurel Leaf

Symptoms:
• Large brown blotches on leaves will start to ‘bubble’ revealing the larvae feeding between leaf layers
• Leaves eventually yellow and drop
• Damage is cosmetic; does not usually kill trees

Life Cycle:  Adult moths overwinter, emerge in spring and lay eggs on undersides of leaves. Eggs hatch, larvae feed, spin silken covering on leaves or on ground. Adults emerge in August, overwinter

Controls - Cultural or Non-chemical:
• Rake affected leaves well in fall
• Apply Horticultural Oil at summer dilution rate, in spring RIGHT AFTER leaves emerge
• Keep trees well-watered and fertilized

Controls - Chemical: Not available


Woolly Bear Caterpillar (Spotted Tussock Moth Larvae)

Wooly Bear CaterpillarPlants Affected: Numerous

Symptoms:
• Fuzzy, black and yellow caterpillars are seen feeding on the edges of leaves
• Damage is cosmetic and usually minimal

Life Cycle:
• Overwinters as pupa in the soil
• Adult moths fly from mid-June to mid-July, laying eggs on the undersides of host plants
• Larvae hatch about 1 week later and begin feeding on leaves
• Larvae will migrate if food source runs out or the host is too mature

Controls:  No control recommended


DISEASES
Select the disease from the images below for more information:

Apple ScabBlack KnotBlack SpotBronze Leaf Disease of AspenCytospora Canker

 

 

 

 

 

 Entosporium Leaf SpotFireblightJuniper-Hawthorn RustLilac BlightNeedle Cast

 

 

 

 

 

Oak Leaf BlisterPowdery MildewRaspberry Blight – SpurRaspberry Blight – CaneRust

 

 

 

 
 
 
 
 

Saskatoon-Juniper RustShot HoleVerticillium Wilt

 

 

 

 

 


Apple Scab

Apple ScabApple ScabPlants Affected: Apple

Symptoms:
• Fruit develops distinctive scabs on the skin
• Leaves develop brown “scorched” areas; damage often mistaken for fireblight

Life Cycle:
• Fungus overwinters on infected leaf and fruit debris from the previous season
• Spores travel on the wind and infect wet leaves, flowers, and fruit

Controls - Cultural or Non-Chemical:
• Rake up leaves and discard fruit
• Keep trees well-watered and fertilized
• Plant disease resistant varieties

Controls – Chemical:  None available


Black Knot

Black KnotPlants Affected: Members of the Rose Family and especially Prunus; primarily Schubert Chokecherry, Wild Chokecherry, and Mayday

Symptoms:
• Initially, new knots start out as branch swelling
• Large black ‘knots’ (cankers) appear on branches the following year
• Spreads to the trunk, eventually killing the tree after a number of years

Life Cycle:
• Mature cankers release spores in summer, which travel on the wind
• Spores infect wet tissue on susceptible plants, especially those that are stressed out or damaged

Controls - Cultural or Non-Chemical:
• Prune out knots at least 12 inches below affected area, clean pruners with bleach/alcohol after every cut
• Dispose of infected branches by burning or burial
• Keep trees well-watered and fertilized

Controls – Chemical:  None available


Black Spot

Black SpotBlack SpotPlants Affected: Numerous, especially Rose

Symptoms:
• Round black spots form on leaves, stems and leaf stalks
• Plants will most likely not be killed but can be severely stressed

Life Cycle:
• The fungus overwinters on infected leaf debris from the previous season
• Spores travel with wind and colonize on wet foliage

Controls - Cultural or Non-Chemical:
• Affected leaves or flowers can be pruned out and discarded.  DO NOT COMPOST
• Keep plants well-spaced to improve air circulation
• Water in the morning and avoid wetting the foliage
• Keep affected plants well-watered and fertilized
• Cut back all dead foliage to ground level in fall to prevent reinfection next year
• Natria Bio-fungicide can be applied as a preventative in 5 day intervals, starting in June

Controls – Chemical:
• Safer’s Defender can be sprayed in 7 day intervals as a preventative on plants that have been previously infected
• Garden Sulphur can be dusted onto affected plants to suppress spores


Bronze Leaf Disease of Aspen

Bronze Leaf of AspenPlants Affected: Poplar, Swedish Columnar Aspen, Trembling Aspen

Symptoms:
• First appears in mid-summer; leaves form yellowish, orange brown or reddish brown discoloration near leaf margins
• Discolored areas expand to cover the whole leaf except for the veins
• As discoloration spreads, it turns bronze in color
• Branch die back can occur as disease spreads; the entire tree can be killed in 3-5 years

Life Cycle:
• Fungus overwinters on infected leaf debris, both on and off host trees
• Spores travel on the wind to infect other trees in spring and summer

Controls - Cultural or Non-Chemical:
• Remove infected branches and leaves, disinfect pruners with bleach after each cut
• Good fall clean-up is essential
• If any infected leaves or branches are on the tree in the fall remove them
• Keep trees well-watered and fertilized
• Avoid overplanting aspen and poplar; consider alternatives for Swedish Columnar Aspen such as ‘Dakota Pinnacle’ or ‘Parkland Pillar’ Birch

Controls – Chemical: None available


Cytospora Canker

Cyytospora CankerCyytospora CankerPlants affected: Evergreens

Symptoms:
• Needles start off yellow, in summer turn purple
• During periods of wetness, gelatinous threads can be seen
• Cankers form with sunken ridges, girdle branches, cause dieback

Life Cycle:
• Secondary fungal disease—moves in on sun scalded wood, stressed trees
• Spores are released onto the wind from gelatinous fruiting bodies

Cultural Control:
• Prune out affected sections
• Keep trees well-watered and fertilized

Chemical Control: None available


Entosporium Leaf Spot

Saskatoon Leaf SpotPlants affected: Saskatoon

Symptoms:
• Small angular brown spots on leaves, often with a yellow halo or margin around spots
• Heavy spotting can cause dark brown spots on fruit

Life Cycle:  Fungus overwinters on leaf debris. In wet weather spores are spread by wind and water splashing

Controls – Cultural or Non-chemical:  Thorough leaf cleanup in fall

Controls – Chemical:  Preventative applications of copper spray, applied in 5-7 day intervals


Fireblight

FireblightFireblightPlants Affected: Rose Family - Apple, Crabapple, Pear, Mountain Ash, Cotoneaster

Symptoms:
• Dramatic wilting at tips of new growth—shepherd’s crook
• Scorched appearance of leaves and clear, amber liquid may be seen oozing from plant

Life Cycle:
• Bacteria overwinter on cankers on infected trees
• Splashing rain or insects transfer bacteria from infected trees to healthy ones during the growing season

Controls - Cultural or Non-Chemical:  Prune out affected branches 12” below infected area.  Disinfect tools with bleach between EVERY cut

Controls – Chemical:  Copper or sulphur—spray on plant in mid-June—this acts as a preventative.  Sprays do not offer control once bacteria is present


Juniper-Hawthorn Rust

Juniper Hawthorn RustJuniper Hawthorn RustPlants Affected: Juniper/Cedars, and Hawthorn, Crabapple, Apple, Mountain Ash

Symptoms and Life Cycle
• Galls form on juniper/cedar branches
• After spring rains, galls ooze gelatinous ‘spore horns’
• On alternate hosts (hawthorn, etc.), yellow-orange spots show, later become orange-yellow surrounded by red bands. These will then release spores in June/July, infecting junipers/cedars in the area

Controls - Cultural or Non-Chemical:
• Eliminate a host (note: neighbours could still have one of the hosts)
• Prune out juniper galls in late winter/early spring before spore horns emerge
• Keep plants well-watered and fertilized

Controls – Chemical:  Copper fungicide (Bordo) should be sprayed on Hawthorns and other alternate hosts foliage as plants start to bloom, then repeated twice at 7-10 day intervals


Lilac Blight

Lilac BlightPlants affected: Lilac, Blueberry, Maple

Symptoms:
• Early spring foliage curls up/twists
• Brown spots with yellow halos
• Infected leaves and flower buds emerge and quickly turn black and die.

Life Cycle:
• Bacteria overwinter on leaf debris and in the soil
• Emerges in the spring when weather is cool and rainy
• Spreads via splashing water or insects

Controls – Cultural/Non-chemical:
• Good fall clean-up of all leaf debris
• Keep plants well-watered and fertilized

Controls – Chemical:  Apply copper spray as a preventative in spring


Needle Cast

Needle castNeedle castPlants Affected: Spruce

Symptoms:
• Mimics winter injury - starts as light green to yellow spots, which turns to brown or red
• Black spores will be seen on needles prior to drop (early spring)

Life Cycle:
• Fungus overwinters on newly infected needles, which remain green until the following spring
• Spores are spread in spring on browning needles (second year following infection)

Controls - Cultural or Non-Chemical:
• Keep trees well-watered and fertilized

Controls – Chemical: None available


Oak Leaf Blister

Oak Leaf BlisterPlants Affected: Oak

Symptoms:
• Slight yellowing of leaf surface followed by raised blisters
• Tree may prematurely defoliate in late summer

Life Cycle:  Fungus overwinters on bud scales and in bark crevices

Controls - Cultural or Non-Chemical:  Lime Sulphur applied to bark crevices and bud scales in fall or spring, when leaves are not present

Controls – Chemical: None available


Powdery Mildew

Plants Affected: Numerous, especially Beebalm, Columbine, Delphinium, Goldenrod, Jacob’s Ladder, Lungwort, Meadowsweet, Speedwell, Stonecrop, Summer Phlox, and others

Powdery MildewPowdery MildewSymptoms:
• White powdery spots, yellowing leaves
• Plants cannot manufacture as much food as they need; severe infestations can kill or severely stunt plants

Life Cycle:
• Fungus overwinters on infected leaf debris from the previous season
• Spores travel on wind and infect wet foliage
• Most prolific during summer weather where days are hot and dry and nights are cool and humid
• Weeds are frequently responsible for harbouring and spreading the disease

Controls - Cultural or Non-Chemical:
• Keep plants well-spaced to improve air circulation
• Clip off infected sections
• Perennials that are badly infected can even be cut back to ground level and allowed to regrow
•Keep well-watered and fertilized; liquid kelp and high potassium fertilizers aid in recovery
• Water in the morning only and avoid wetting the foliage
• Cut back all dead foliage to ground level in fall to prevent reinfection next year
• Keep beds well weeded
• Natria Bio-fungicide can be applied as a preventative in 5 day intervals, beginning in June

Controls – Chemical:
• Safer’s Defender can be applied as a preventative in 7 day intervals, beginning in June
• Garden Sulphur can be dusted onto affected plants to suppress spores


Raspberry Blight - Spur

Raspberry BlightPlants affected - Raspberry

Symptoms:
• Edge of older leaves have V shaped lesions. Advances to mid veins then to the leaf axil where new growth occu
• Lowest leaves affected first, then moves upwards.

Life Cycle: Spores are discharged from May to August coming from old fruiting canes. Secondary spores (conidia) are also produced and those spores splashed about in July/August probably cause the most damage

Cultural Control: Provide good spacing between rows

Chemical Control - Apply preventative applications of Natria or Copper starting in mid to late June


Raspberry Blight – Cane

Raspberry Cane BlightPlants Affected: Raspberry

Symptoms:
• Purple spots with grey-white centres form on new canes, leaves. Spots enlarge to form sunken pits. On second-year canes lesions can coalesce into cankers that girdle the cane
• Fruit symptoms include shrunken brown druplets or withered, dry seedy fruit

Life Cycle:
• Ascospores are rain-splashed and air-borne from infected canes in early spring
• Conidia are rain-splashed from overwintering infected canes in the spring and throughout the summer to new growth
• Infection requires three to twelve hours of wetness; only very young green tissue is infected

Controls – Cultural/Non-chemical:
• Prune out damaged canes
• Apply preventative applications of Natria Bio-fungicide starting in mid-June every 7 days

Controls - Chemical:  Apply preventative applications of Copper Spray starting in mid to late June every 10 days


Rust

RustRustPlants affected: Numerous, in particular Hollyhock, Speedwell, Stonecrop

Symptoms:
• Orange to red spots appear on foliage and sometimes flowers or fruit. Oftentimes, these turn brown or black over time and may release powdery orange spores. Frequently the spots have a “blistery” appearance
• Damage is usually cosmetic

Life Cycle:
• A complex fungus whose life cycle usually involves two or more hosts
• Usually overwinters on infected plant debris from the previous season or on an alternate host
• Alternate hosts are frequently weeds, from which spores are produced which travel on the wind to garden plants, infecting wet foliage
• Spores produced on infected garden plants then travel back to the alternate host to re-infect

Controls – Cultural or Non-chemical:
• Keep beds well-weeded
• Keep plants well-watered and fertilized
• Water in the morning only; avoid wetting foliage
• For minor infections, remove affected plant parts
• Natria Bio-fungicide can be applied as a preventative in 5 day intervals, starting in June

Controls – Chemical:  Copper spray can be applied as a preventative in 7 day intervals, starting in June; can also be applied in 5 day intervals on infected plants to suppress spores


Saskatoon-Juniper Rust

Saskatoon Juniper RustPlants affected: Saskatoon

Symptoms:
• Infected leaves and berries develop yellowish-orange spots
• Later in season, spots may be covered with spiny projections (like whiskers)
• leaf can tolerate large quantities of spots, but one spot ruins the berry
• Two hosts; overwinters on Juniper plants

Controls - Cultural/Non-chemical:
• Remove junipers growing nearby
• Keep plants well-watered

Controls – Chemical:  Preventative sprays of copper fungicide starting in June


Shot Hole

Shot HolePlants affected: Numerous, in particular Prunus (Plum, Cherry, Chokecherry, Apricot)

Symptoms:  Numerous tiny, perfectly round holes appear right through the leaves

Life Cycle:  Overwinters in leaf debris – is caused by both a bacteria and fungus

Cultural Control:  Good fall clean-up

Chemical Control:  Copper fungicide in spring as a preventative starting in mid-June


Verticillium Wilt

Verticillium WiltVerticillium WiltPlants affected: Numerous, especially Elder, Maple, Ohio Buckeye, Virburnum (see list below)

Symptoms:
• Caused by soil borne fungi. Midsummer, leaves turn yellow at margins then brown and dry. Sudden wilting on one or several branches may occur
• Frequently the foliage on only one side of tree wilts
• Wood under bark of affected branches is discoloured in streaks. Affected plant may die in one season or after several seasons
• Life Cycle - Fungi remain in soil for several years, attack root system of plant

Controls – Cultural/Non-chemical:
• Do not replant susceptible species in same spot. See listing below.
• Prune out affected limbs and fertilize to maintain vigour

Controls – Chemical: None available.

Verticillium wilt susceptible plants:
Ash
Box Elder
Buckeye, Ohio
Cherry and other Prunus
Currant
Elder
Elm
Honeysuckle
Horse Chestnut
Lilac
Maple
Rose
Russian Olive
Serviceberry
Sumac
Viburnum
Weigela

Verticillium wilt resistant plants:
Apple
Birch
Crabapple
Dogwood
Fir
Hawthorn
Juniper
Larch
Linden
Mountain Ash
Oak
Pear
Pine
Spruce
Willow
Yew


CULTURAL DISORDERS
Disorders are plant abnormalities that are caused by environmental factors such as nutrient availability or temperature (not pests or diseases). Typically, disorders may make your plant look different than expected but unless severe, are not usually overly harmful.
Select the disorder from the images below for more information:

 

ChlorosisFrost CrackGummosisHerbicide DamageOverwateringUnderwatering

 

 

 

 

 


Chlorosis
Chlorosis

Symptoms:
• leaves are yellow but veins remain green, may be some browning on the margins of leaves
• will be evident first on new growth, then work back to older leaves on a branch

Control:
• ensure loose, well-drained soil, avoid overwatering
• high soil alkalinity can also be a cause, plants can be fertilized with iron chelate for recovery


Frost crack

Frost Crack

Symptoms:
• vertical cracks present in bark on trunks of trees
• fruit trees very susceptible to this

Controls:
• due to fluctuating temperatures in winter months
• mulch bases of trees with bark mulch, ensure plants are well hydrated before final freeze up in autumn


GummosisGummosis

Symptoms:
• very common on fruit trees, especially cherries

Control
• causes vary from mechanical damages such as sapsucker damage, squirrel damage, wood boring insects or delayed winter injury, which is common in fruit trees
• beyond avoiding these, let the wounds heal over on their own


Herbicide Damage

Herbicide Damage

Symptoms:
• curling or cupping leaves
• discoloration between veins
• twisted, elongated stems

Control:
• use all herbicides according to label, note that herbicide can drift for several miles, it’s very difficult to ascertain where chemical drifts from
• keep damaged plants well-watered, most plants will recover


Overwatering

OverwateringSymptoms:
• wilting, yellowing leaves
• leaves will yellow from outside in
• Note: wilting is a symptom of BOTH over and underwatering, if plants are wilting don’t assume they require moisture until soil is checked by hand

Controls:
• plants in lower lying areas will suffer in times of heavy rains; plant appropriate species in these areas
• for new and established plants, water only as required; check soil prior to watering

 

 


Underwatering

Underwatering

Symptoms:
• wilting, crispy or browned leaf edges

Controls:
• water, especially for new transplants should be monitored daily during periods of extreme heat
• for new transplants, stick your hand into the soil to determine if moisture is required