You have reached Jen Llewellyn for the 15th edition of the 2013 OMAF and MRA Nursery and Landscape Report, updated on Friday, August 2nd.
Environment Canada is calling for sun and cloud and continued cool (low 20’s) temperatures for this long weekend with reduced humidity. Some unsettled weather is arriving this afternoon and evening and showers with possible thunderstorms are in the forecast for many areas. It’s going to stay cooler than normal for several days, perfect weather for Star-gazing and planting Nursery Stock 🙂
We have been doing a lot of scout and so far, the 2nd generation of Euonymus scale crawlers have not hatched yet. If you look under the female scales (tiny, brown, oyster shell appearance) on the stems, you will see that they still are orange and fleshy (see images below). They are starting to lay eggs inside that flesh and those eggs will hatch into bright orange crawlers in the next couple of weeks. Make sure you monitor closely to ensure that the crawler stage is present before applying pesticides.
Are you seeing discoloured, wilted or dead tops on White Pine?
I have had a lot of inquiries about a strange disease that is causing weeping and dieback on the tops of white pine, often they break off easily.
The bark is discoloured, reddish-brown and a little sunken into the stem.
If you slice down shallowly below that bark, you will see the inner tissue is brown and dried up. It almost looks “chewed” but you can’t find any insects?
Take your pruners and slice longitudinally into the stem, cutting and tearing down the middle of the stem, what do you see? Do you see little empty chambers? Are there any little white insects inside?
Aha! These are larva, pupa and …..adults of the White Pine Weevil. The larvae feed in the cambium just under the bark and when they are ready to pupate, they move to the centre of the stem to create pupal chambers where they will undergo metamorphosis into adults. I actually caught an adult in this sample as well….
Destroy stems as soon as possible to try and limit the number of successfully pupated adults. It’s getting a bit late for cultural management of white pine weevil because many adults have already emerged.
Plant Phenology indicators this week.
A) North of 401 (700-900 GDD Base 10oC): Cirsium arvense (Canada thistle, blooming, seed ripening), Daucus carota (wild carrot, full bloom), Hydrangea arborescens ‘Grandiflora’ (late bloom to flowers starting to turn green), Sorbus aucuparia (European Mountain ash, fruit is yellow)
B) Niagara: (700-900 GDD Base 10oC): Cirsium arvense (Canada thistle, blooming, seed ripening), Daucus carota (wild carrot, full to late bloom), Hydrangea arborescens ‘Grandiflora’ (white flowers turning green), Sorbus aucuparia (European Mountain ash, fruit is yellow)
C) London area: if you would like to report plant phenology events, please contact me.
D) Leamington-Windsor: if you would like to report plant phenology events, please contact me.
If you are referring to the Monitoring tables in the 2009 edition of publication 383, Nursery and Landscape Plant Production and IPM, look at Tables starting on pg. 64.
PLEASE NOTE: The Following 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.
Nursery-Landscape Insect Pest ID: Dave Cheung’s Common Pests of Nursery-Landscape database to help ID your problem pests. Check out
Growers. Thursday, August 15 at J.C. Bakker & Sons Nurseries. “Intelligent Sprayer Demo Day”. If a new sprayer design could reduce crop protection inputs by 70 per cent, would you be interested? Come and see for yourself, the “intelligent sprayer”, designed and customized for nursery production systems, will be demonstrated for its efficiency and efficacy on real-life commercial nursery crops. Dr. Heping Zhu, well known for his extension work at Ohio State University and associate Randy Zondag will be sharing their latest research with us in St. Catharine’s. Rain day: August 16. RSVP only. To register, click here.
Growers, Landscapers, Garden Centres: The Annual LO Growers Research Plant Auction is coming up on Wednesday, August 14 at Sheridan Nurseries. Come in the morning for farm tours, come for lunch, come to the LIVE Auction starting at 1:00 pm. Bring your trailer. No RSVP required.
Are you seeing webbing around the ends of branches on deciduous trees such as ash, birch and cherry? Look inside the webbing and look for yellow, fuzzy caterpillars. These are fall webworm caterpillars and they usually start to show up on the ends of branches this time of year. Prune out nests and destroy them to prevent future colonies from infesting your trees. Pole loppers are an awesome tool for managing fall webworm caterpillar nests! Spraying is not necessary or necessarily effective unless there are high populations of nests.
Have white grubs been an issue in your nursery? Preventative applications of Intercept (imidacloprid) are registered for white grubs (nursery production) and the application period is in June and July (during the adult flight period for the adult stage) should be finished. To help qualify for the Japanese beetle certification program, an application of Intercept 60WP on container stock or field stock should made between mid-June to July (adult flight period). The cut-off period for Intercept applications to comply with the JB Certification program this year may be as early as July 31st. Beneficial nematode applications for white grubs (e.g. European chafer) will be effective in mid-August. Order your nematodes at least a week in advance of application.
Japanese beetle adults are flying and feeding on leaves of woody plants (Syringa, Tilia, Ulmus, Prunus, Rosa). Look for metallic, coppery-green beetles with white turfts of hairs along the edge of their abdomens.
Adulticide insecticides for JB in the nursery include Sevin XLR and Thionex. Pheromone traps for JB are extremely good at attracting the adults. Always place traps far AWAY from susceptible host trees and shrubs (e.g. roses, cherry, linden, elm, lilac etc.).
Black vine weevil adults and Strawberry root weevil adults are actively feeding on woody and herbaceous plants at night this time of year. They feed by chewing out notches in leaf or needle edges. Adult feeding is not usually detrimental to plant health but the next generation of larvae that hatch from their eggs IS damaging to plant roots. Actara 25G, Scimitar SC, Sevin and Thionex are registered as adulticides for weevils in the nursery.
DECIDUOUS WOODY AND HERBACEOUS PERENNIALS:
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 (biofungicide), Tivano] where the history of disease pressure is moderate to high.
Tar spot is rearing its ugly fruiting structures on Norway maple at this time. Look for yellow halos that are filling in with black dots (those are the fruiting structures). There is nothing you can do to prevent disease symptoms as infection took place back during leaf emergence in May. Rake and remove newly fallen leaves or mow them to help encourage their complete breakdown before fruiting structures sporulate next spring.
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.
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. The regulated areas for Emerald Ash Borer in Ontario and Quebec can be found at:
Honeylocust Spider Mite NYMPHS and ADULTS can be found on Honeylocust trees this time of year. They can really ramp up their populations during hot, dry weather so monitor for mites and injury on susceptible trees (e.g. juvenile nursery stock, stressed landscape trees). Mites are not usually a significant threat to healthy trees. Treat nymphs with Insecticidal Soap or the summer rate of horticultural oil to reduce populations. Orthene is registered for nursery crop production.
Potato leafhoppers NYMPHS and ADULTS may still feeding on woody nursery stock on the newest growth. Monitor for potato leafhopper on nursery crops such as Caragana, and Acer (platanoides, saccharum). Nymphs are about 2 mm long and scuttle SIDEWAYS, rather quickly, across the leaf and to the other side (they don’t have wings to fly away). Susceptible crops are those that are flushing new leaves (leafhopper’s favourite food source). Leafhoppers are also attracted to yellow sticky cards, for monitoring. Registered insecticides include Tristar and Sevin XLR.
Aphids were quite numerous on herbaceous and woody ornamentals this year but their popuations have really dropped off as most foliage is hardened off. 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.
Gypsy moth adults are emerging. Males fly erratically in search of flightless females.
Sticky bands around trunks during the flight period will help prevent adult female Gypsy moths from laying eggs above sticky bands and will attract males to the sticky surface. Pheromone-baited sticky traps are also available to help reduce populations of adult males.
Two-spotted spider mites (TSSM) are feeding on several types of deciduous woody (Viburnum and Spiraea in container production) and herbaceous perennials. Look for chlorotic leaves with stippling, use your hand lens to see tiny, clear bodied mites with dark regions (may be faint black) on their backs. These 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). Stethorus punctillium is a new beetle that is a good predator of TSSM.
Magnolia scale appears as large, white scales turning pinkish-orange scales (some may still have a dusting of white powder). They will be laying their eggs in the next few weeks. Pick off the scale insect and look at the underside: if it is still fleshy, they haven’t laid their eggs yet. If tiny, white grains can be seen (like salt grains), they have started laying their eggs. Crawler hatch usually starts early August (~1200 GDD 10oC). If you want to try insecticides against the crawler stage, make sure you are making at least 2-3 repeated applications, 7 days apart. This will have much better knockdown since crawler emergence is staggered. Insecticidal soap and the summer rate of horticultural oils should give good knock down. Malathion, Orthene and Sevin are registered for this pest in the nursery.
The 2nd generation of Pine Needle Scale Eggs (dark maroon red) and Crawlers (dark red with legs) are hatching with some Settled Nymphs (yellow-ish brown) mixed in to the population on white, Scots and mugo pine. They are susceptible to several contact insecticides including insecticidal soap. Good coverage is important for management with insecticides.
Taxus or Fletcher Scale crawlers (left) have settled on needles and NYMPHS are feeding on new needles (right). These eggs were hatching over the last few weeks ( look for “eggs with legs“). Crawlers are really tiny, clear-white and REALLY difficult to see. Crawlers will hide under females shells and will hatch over a period of 2-3 weeks. Therefore, two-three applications of insecticide will be needed to reduce crawler populations and reduce further injury. Insecticidal soap and several contact insecticides are registered for Fletcher scale crawlers and a little less so on NYMPHS.
The second generation of Euonymus scale crawlers HAVE NOT HATCHED YET in most areas. Euonymus scale look like tiny white (males) and brown (females) flecks along twigs and the undersides of leaves. Look for another generation of bright, orange crawlers around populations of adults and on the undersides of leaves and twigs. Where insecticide applications are warranted, multiple applications may be required to get good knockdown since crawler emergence is staggered over a few weeks. Try insecticidal soap and the summer rate of horticultural oil.
Monitor for black vine weevil ADULTS in the FIELD and LANDSCAPE for Rhododendron, Taxus, Thuja and Euonymus. It’s too late for applications of nematodes in the field/landscape. Strawberry root weevil can also be a problem in field production of evergreens, adults have emerged. Signs of strawberry root weevil adults include brown, flagging shoot tips (and small girdling marks at the base of the flagged shoot) on Thuja (eastern white cedar). To scout for adult weevils, place a tarp or large piece of card board under the tree, shake branches vigorously and look for brown-black weevils “playing dead”. Insecticides for adult weevils in the nursery include Pounce, Sevin and Thiodan. Remember, adult weevils feed at night. Spray insecticides in late evening to target adults and reduce UV degradation (e.g. Pounce, Scimitar).
Cedar leaf miner (CLM) next generation larvae are starting to hatch and feed on tender new foliage. A light sheering of tips in early August should give good knockdown of CLM larvae. Cygon is registered as a foliar application for CLM larvae in early August in the nursery.
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.
THIS MESSAGE WILL BE UPDATED the week of August 12.