June 24 Nursery & Landscape Report

Environment Canada is calling for cloudy, humid unsettled weather with the chance of showers or thunderstorms today and tomorrow.  There is a mix of sun and cloud forecasted for the rest of the week with high temperatures, moving into the high 20’s.  Happy first week of summer!

Plant Phenology indicators this week.  A) North of 401 (300-400 GDD Base 10oC): Catalpa speciosa (early bloom), Syringa reticulata (early to mid bloom), Kolkwitzia amabilis (finishing bloom), Spiraea nipponica (full bloom), Cornus alternifolia (late bloom),  Weigela florida (full bloom)

B) Niagara )400-500 GDD Base 10oC) : Catalpa speciosa (full bloom), Syringa reticulata (late bloom),  Spiraea nipponica (late bloom), Sambucus canadensis (early bloom)


1) Arboriculture and Landscape Professionals:  ISA Workshop: “IPM in the Woody Landscape”.  WORKSHOP IS FULL, WAITING LIST ONLY.  Tuesday, July 15 at the University of Guelph Arboretum Centre.  Come spend the day learning about current pests and physiological problems on trees and shrubs.  This workshop will be led by Jen Llewellyn with Dr. Shannon Shan and Sean Fox. CEU’s are available.


2) GrowersNursery Growers Research Auction.  Wednesday, July 16 at Winkelmolen NurseriesLandscape Ontario’s Growers Group invites you to its annual fundraising auction
No admission fee or RSVP required. Bid on top quality plant material and tour the production farm while helping raise funds for industry research and scholarships.  All winning bidders will be entered into a draw for a special prize. Enjoy lunch, network with peers and bid on fantastic items – something for everyone!


  • Farm Tours:  10:00 a.m. – 11:30 a.m.
  • Lunch and Refreshments:  11:45 a.m. – 12:45 p.m.
  • Live Auction: 1:00 p.m. – 4:00 p.m.

3) Landscapers and Arborists:  “OMAF Sprayer Coverage and Calibration Workshop”Friday, July 18. 

  Come to the Landscape Ontario office in Milton to learn from OMAF’s own Application Technology Expert, Dr. Jason Deveau.  Jason is an expert in helping horticultural producers increase coverage and improve efficacy and this year, Jason is bringing his expertise to landscape and arboriculture professionals.  Jason will take you through sprayer calibration for landscape equipment and show you how to assess and improve coverage.  This 3-hour HANDS-ON workshop is perfect for landscapers and arborists that apply pesticides and fertilizers.  To register, contact Kathleen at LO at kathleenp@landscapeontario.com


DSC_0314  Japanese beetle adults have been sited in the Hamilton region.  Adults are just starting to emerge in southern Ontario.  European chafer adults should be emerging any day now.

Have white grubs (e.g. European chafer, June beetle) or Japanese Beetle phytosanitary restrictions been an issue at your nursery?  Preventative applications of Intercept (imidacloprid) are registered for white grubs in nursery production and the application period is in June and July (during the adult flight period for the adult stage).

To help qualify for the Japanese beetle certification program, an application of Intercept 60WP on container stock or field stock should made between late-June to August 15 (JB adult flight period).  The cut-off period for Intercept applications to comply with the JB Certification program this year will be August 15.   

Adult Black Vine Weevil black vine weevil

and Strawberry root weevils O_ovatusAdultDC

are emerging and starting to feed on various evergreen and deciduous hosts in field and container grown ornamentals.

Look for Strawberry root weevil adults in spruce, eastern white cedar and sometimes in juniper. SRW’s will chew notches in small twigs, girdling them and causing the shoots to turn brown.

SRWDamageOld SRWFlagging

Look for adult black vine weevils in yews, eastern white cedar and euonymus. BVW adults will chew notches in the margins of leaves.


The soil dwelling larval stage of these weevils is the most damaging life stage but is difficult to control in field soil.  Adults can be managed in nursery production with insecticides such as Actara, Scimitar SC, Sevin and Thionex.  Monitor for adults by placing out wet boards or burlap on the ground underneath the crop.  Monitor for weevils under the board/burlap during the day.  Alternatively you can shake the canopy onto a light coloured sheet and count adults that fall on the sheet.


image0001 image0006 We have seen more powdery mildew on deciduous flowering shrubs (Amelanchier, Rosa) and herbaceous perennials.  Monitor for white, powdery residue on the tops and bottoms of leaves.  Protect new foliage with fungicide applications (e.g. Switch, Milstop, Regalia (bio)) where the history of disease pressure is moderate to high.


Our nursery scout saw fall webworm adults laying their eggs recently on the foliage of deciduous trees (cherry, ash, apple, birch etc.).  Fall webworm larvae form very strong webby tents on the ends of branches from where the feed inside on foliage.  Prune out fall webworm nests and destroy to reduce the next generation of adults.  There are several generations of fall webworm that cycle through the summer and become more numerous by August and September.

Peach tree borer (Synanthedon exitosa) adults are flying for the next few weeks. Look for cankered regions and chewed bark/wood in the lower stems of Prunus (Prunus x cistena) as a sign of larval damage.  These clear-wing moths resemble wasps. PeachTreeBorerAdultMale

Adult Peach tree borer moths are very much attracted to sticky wing traps that are baited with peach tree borer pheromones. Place pheromone traps out in early-mid June (approximately 390 GDD Base 10oC, ‘Red Prince’ Weigela in full bloom) and monitor for peak flight of adults.  You can expect peak egg hatch around 10-14 days later, if you are thinking of treating newly-hatched larvae.  The same ‘clearwing moth’ pheromones and traps can be used to monitor for Viburnum borer.  Viburnum borer chews the stem (at and below the soil line) and causes significant injury to container grown Viburnum.  Viburnum borer will be starting to emerge in container production at this time.  To purchase traps, try ordering from IPM suppliers such as www.greatlakesipm.com and www.naturalinsectcontrol.com.   Some growers are trying soil drench applications of beneficial nematodes, S.c., (Steinernema carpocapsae) after peak adult flight, as a biological way to suppress hatching larvae.  We found that bark applications of S.c. gave a significant reduction in # larvae in a field trial last year.

Emerald ash borer adults are flying and feeding on ash leaves at this time. Look for adults casting shadows on leave in upper canopy on sunny days.

EAB adults casting shadows on leaves (Markham)

EAB adults casting shadows on leaves (Markham)

Injectable insecticides may be used to protect ash trees from new infestations of Emerald Ash Borer (Agrilus planipennis).  Trees must be actively transpiring in order to maximize insecticide uptake into the cambium.   Registered injectable insecticide products include: AceCap 97, Confidor 200 SL and Tree-Azin.  Check out the Management Strategy for Emerald Ash Borer and Bronze Birch Borer at:  http://www.omafra.gov.on.ca/english/crops/insects/eab-bbb-manage.htm.  Emerald ash borer adults start to emerge when the black locust (Robinia pseudoacacia) are blooming.

The regulated areas for Emerald Ash Borer in Ontario and Quebec can be found at:


The regulated areas for EAB outlines restrictions on the movement of all ash species (Fraxinus sp.) materials and all species of firewood from these regulated areas of Ontario and Quebec.

Adult bronze birch borer beetles are actively laying eggs on the bark of susceptible birch (e.g. Betula pendula).  Symptoms of larval boring damage appear as branch tip death, branch death and death of the leader and progresses quite quickly.  Destroy pruned material to prevent emergence of beetles. Natural resistance to this pest can be enhanced through activities that improve plant health, such as light fertilizing (May, October), irrigating and removing any weeds and grasses that provide competition for the tree.  Betula pendula is most susceptible to this pest and should be avoided in areas of known BBB infestation.  Betula nigra and its selections have been shown to be quite tolerant to BBB attack.  Confidor injectable insecticide is labelled for bronze birch borer.

Potato leafhoppers NYMPHS and ADULTS are feeding on woody nursery stock.   Monitor for potato leafhopper on nursery crops such as Acer (platanoides, saccharum), Quercus and Ostrya.  Adults will fly away quickly but nymphs are about 2 mm long and scuttle SIDEWAYS, rather quickly, across the leaf and to the other side (they don’t have wings). Susceptible crops are those that are flushing new leaves (leafhopper’s favourite food source).  Older, hardened off foliage is not usually as susceptible.  Leafhoppers (and aphids) suck plant sap from soft, expanding foliage and cause foliage and stems/petioles to wilt, turn brown/black (‘Hopper Burn”) and become stunted and malformed.


Older, hardened off foliage will become flecked from potato leafhopper feeding.  Monitor populations and treat the 1st generation NYMPHS with insecticides before damage becomes economically threatening.  Leafhoppers are also attracted to yellow sticky cards, for monitoring.  Registered insecticides include Tristar and Sevin XLR.

Aphids are quite numerous on herbaceous and woody ornamentals this year!  They do well in cool weather because leaves stay soft and easy to feed on.  Green peach aphid is one of the most common species and melon aphid and foxglove aphid are also quite common.  This year we are seeing large colonies of black bean aphid (Aphis fabae) on deciduous flowering shrubs and Euonymus.  Aphids are sucking insects that cause stunting, malformation and coat plants in honeydew.  They also attract ants. Various insecticides are registered to manage aphids in outdoor production nurseries including Endeavor, Tristar and Trounce.  In greenhouses insecticides include Endeavor, Intercept and Enstar EW.  Where populations aren’t immediately economically damaging, biological control (e.g. Aphidius, Aphidoletes) may provide excellent management when introduced on a regular basis.  Biocontrol suppliers include Biobest, Koppert, Plant Products and Canadian Hydrogardens.

image0001 Gypsy moth larvae are in their heaviest feeding period as they are late instar larvae at this time.   The love to hide during the day (in bark crevices and underside of twigs, leaves) and can often be found on oak, elm, beech etc. and also Colorado spruce.  Success is a good lower toxicity choice but many broad spectrum insecticides will give good knockdown if it can reach the elusive larvae.  Sticky bands around trunks during the July flight period will help trap female Gypsy moths and will attract males to the sticky surface as well.

Two-spotted spider mites (TSSM) is showing up on several deciduous and herbaceous plants, especially in container production. Use your hand lens to see tiny, clear bodied mites with dark regions (may be faint black) on their backs. <a href="/clm/species/teranychus_urticae"><em>Teranychus urticae</em></a> (Two-spotted Spider Mite).

Two spotted spider mites are small but the damage is significant so catch them early.  Miticides registered for this mite in the greenhouse include: DynoMite, Vendex, Kanemite, Floramite, Avid.  Apollo is registered in outdoor nursery crops to knock down the egg stage and newly hatched nymphs.  In the greenhouse, biocontrol agents should be brought in to coincide with the first sign of TSSM.  Phytoseiulus persimilis is a predatory mite that feeds on TSSM when temperatures are below 26oC and it is a good choice when TSSM populations are low-moderate.  Amblyseius californicus is a predatory mite that can be brought in ahead of TSSM appearance (because it can find other sources of food).


Where new foliage is emerging on conifers and hasn’t hardened off yet, monitor for needlecast and blight diseases in the area.  Diplodia tip blight on 2 and 3 needled pines and Rhizosphaera needlecast and Stigmina on blue Colorado spruce are our most common needlecast diseases in Ontario.  Diplodia tip blight appears as brown, stunted needles at the tips of branches.  Rhizosphaera appears as brown-purplish needles from the previous year’s growth, symptomatic needles begin to drop in late spring.  Stigmina appears on green and chlorotic needles, but doesn’t always lead to needle drop.  To confirm it is Rhizosphaera, look at the undersides of the needles.  Those little white dots (stomata) will turn black and the black spots will protrude during sporulation.  New, soft growth is especially susceptible to foliar diseases, but infection may also take place later in the season (we don’t know).  Where there is a history of damage, treat with registered fungicides (copper oxychloride, Banner Maxx, Daconil) as buds start to open and protect new foliage.  Apply fungicides prior to precipitation events (spore dispersal).  Unfortunately, most of these blights and needlecasts can be found sporulating for much of the year.

The first generation of Euonymus scale crawlers and Fletcher scale crawlers are active on Euonymus and yew (Taxus) at this time and are very susceptible to insecticides.  Try insecticidal soap and where possible the summer rate of horticultural oil in the landscape.

Look for crooked, wilting and browning terminal shoots on pine and spruce with sap weeping and cankered-looking bark, it could be boring larvae from white pine weevil.

DiebackTerminalColSpruceWhite Pine Weevil Injury Terminal

Where appropriate, slice into bark and look for tiny, fat, white, legless grubs feeding in the cambium.


Insecticide control for white pine weevil is too late at this point, prune out and destroy all symptomatic terminals and train a new leader.

image0006  Look for larvae (15 mm long) of  Yellow-headed spruce sawfly feeding on tender new needles of spruce (e.g. Colorado spruce) in the landscape.  Larvae are green with lighter longitudinal stripes, yellow-brown heads.  There are several insecticides registered including Dragnet, Dylox, Pounce and Success to target young larvae.  This is a damaging pest of spruce in York region and has caused significant damage to spruce trees. The bigger they get, the harder they fall.

Cedar leaf miner (CLM) moths may still be active, there are several moth species that are leafminers of Thuja.


Tear along the margin of green and brown tissue and check for the presence of hollowed out tissue to confirm it is cedar leafminer damage.  We have seen quite a bit of CLM in field grown Thuja on sandy soils this spring.  Adulticides (malathion) are registered for the moth life stage in nursery production.


Spruce Spider Mite Monitor for nymphs and adults of spruce spider mite on conifers with a history of mite damage.  Spruce spider mite nymphs and adults are brown with black backs and found on new foliage this time of year.  Miticides registered for SSM include Floramite and Kanemite.  Miticides may be required where pest pressure is moderate to heavy (container grown conifers with overhead irrigation).

PLEASE NOTE: The previous Pesticide Recommendations are meant for Exception Uses (e.g. agriculture) under the Cosmetic Pesticide Ban unless the active ingredient is listed under Class 11 pesticides in Ontario Regulation 63/09, effective April 22, 2009.

 The 2013 Crop Protection Guide for Nursery and Landscape Plants   (previously 383, now publication 840) can now be found at:  http://www.omafra.gov.on.ca/english/crops/pub840/p840order.htm   It contains the crop pest recommendations for nursery and landscape plants that was previously found in publication 383.  Publication 840 is a .pdf file, accessible online and on cd.

OMAF publication 841, Guide to Nursery and Landscape Production and IPM, has now been posted to the website. It contains supporting information on crop production and maintenance in regards to nutrition, irrigation and integrated pest management (including plant phenology tables). To view the pdf, click here: www.ontario.ca/bwa5

Nursery-Landscape Insect Pest ID: Dave Cheung’s Common Pests of Nursery-Landscape database to help ID your problem pests. Check out www.dkbdigitaldesigns.com/clm




About Jen Llewellyn

OMAFRA Nursery and Landscape Specialist @onnurserycrops
This entry was posted in Application Technology, Educational Opportunities, IPM, Weekly Nursery Landscape Report and tagged , , . Bookmark the permalink.

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