You have reached Jen Llewellyn for the 17th edition of the 2013 Nursery and Landscape Report, updated on Monday, August 26th.
Environment Canada is calling for sun and cloud and the chance of more showers this afternoon with high’s in the high 20’s and High Humidity. It’s supposed to clear up later today and sunny skies and continued hot, humid weather is expected to last well into Labour Day weekend.
This is perfect weather for planting late season annuals, mulching tired looking gardens and enjoying the plethora of cricket and katydid songs at night!
Have you heard strange insect noises at night lately? It could be the song of one of our common species of Katydids. Katydids are beautiful insects, found in the same order as crickets and grasshoppers. They feed on leaves but not to the detriment of the plant, they are not plant pests. Their bright green colour helps them blend in perfectly so unless they are “calling”, they are pretty difficult to find. The males produce their song by “stridulation”: rubbing the scraper of one forewing against the toothed edge of the other forewing. It resembles someone running their fingernail down the side of a plastic comb. Check this link out to listen and view the song of the Oblong-winged katydid in a wet Ontario meadow.
For those of you out there that are fed up with dealing with nasty Japanese Beetle adults, take heart. The crab spider is a predator of Japanese Beetle adults (see above) and other insects. I photographed this one after having captured a JB adult on milkweed. It was quite content, sucking out the juices from the poor little beetle.
Plant Phenology indicators this week.
A) North of 401 (1100-1300 GDD Base 10oC): Hibiscus syriacus (Rose of Sharon) (full bloom), Daucus carota (finishing bloom, just a few left), Hydrangea paniculata ‘Grandiflora’ (full bloom), Solidago canadensis (Canada goldenrod) (mid to full bloom).
B) Niagara: (1100-1300 GDD Base 10oC):
Hibiscus syriacus (Rose of Sharon) (full bloom), Daucus carota (finishing bloom, just a few left), Hydrangea paniculata ‘Grandiflora’ (full bloom), Solidago canadensis (Canada goldenrod) (mid to full bloom).
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.
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 or lawn? Applications of Beneficial nematode for white grubs (e.g. European chafer) will be effective in mid-August against early instar larvae in the soil. Order your nematodes at least a week in advance of application. Irrigate soil prior to application. Never apply nematodes in direct sunlight and water well for 10-14 days after.
Japanese beetle adults are still flying and feeding on leaves of woody plants
(Syringa, Tilia, Ulmus, Prunus, Rosa) but populations are starting to go down. Look for metallic, coppery-green beetles with white turfts of hairs along the edge of their abdomens. Adult insecticides for JB in the nursery include Sevin XLR and Imidan. 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. Drenches of beneficial nematodes (Heterohabditis bacteriophora) will be effective when applied to nursery container grown woody and perennial ornamentals in early-mid September to catch the next generation of larvae.
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: http://www.inspection.gc.ca/DAM/DAM-plants-vegetaux/STAGING/images-images/pestrava_agrpla_ministerial_image1_1337371924902_eng.gif
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, pinkish-orange scales (some may still have a dusting
of white powder). The crawlers have all hatched and are feeding on undersides of stems. Crawlers are settling into nymphs at this time and are less susceptible to insecticides. 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.
Taxus or Fletcher Scale nymphs have all settled on needles and are feeding on new
needles (right). These settled nymphs are much less susceptible to insecticides. Nymphs will migrate from needles to twigs in early September, a late season insecticide rescue treatment may be possible in early September where warranted to suppress this life stage.
The second generation of Euonymus scale crawlers HAVE HATCHED and they are settling as NYMPHS at this point. Euonymus scale adults look like tiny white flecks (males) and brown oystershell-like (females) along twigs and the undersides of leaves. Where insecticide
applications are warranted, multiple applications will 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 are active. 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 next generation larvae are starting to 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 September 9th.