Magnolia Scale is just NASTY this year.
CRAWLERS have hatched but are still hiding underneath the female scales. Pick off scales to reveal dark grey eggs and crawlers (eggs with legs) underneath.
The crawlers will hatch and gradually emerge out from under the dead female mothers over the next week or two. Contact insecticides (traditional insecticides, insecticidal soap, horticultural oil) can be used to manage crawlers once they emerge and start feeding on twigs.
If you miss the Magnolia scale crawlers, don’t worry. They overwinter as tiny, dark grey nymphs on the undersides of twigs. It is advisable to go in with a fall dormant oil spray (with emphasis on contacting undersides of twigs) to significantly reduce the population in October.
Plant Phenology indicators this week.
Solidago canadensis in mid bloom; Sorbus aucuparia with orange fruits; Hydrangea paniculata ‘Grandiflora’ (late bloom, white flowers turning pink). This puts us at 1100-1200 GDD Base 10oC depending on location.
OMAFRA Publication 840, Crop Protection Guide for Nursery and Landscape Plants can 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 it out !!!
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
Are you seeing webbing around the ends of branches on deciduous trees such as ash, birch, walnut 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 effective.
Have white grubs been an issue in your nursery? Preventative applications of Acelepryn are registered to help protect nursery crops from this pest and they are effective any time the larval stage is present in the root zone. [Beneficial nematode applications for white grubs (e.g. European chafer) are not effective at this time].
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 tufts 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 actually too good at attracting the adults. Always place traps far AWAY (I mean away!) from susceptible host trees and shrubs (e.g. Rosa, Prunus, Tilia, Syringa, Ulmus etc.).
DECIDUOUS WOODY AND HERBACEOUS PERENNIALS:
We have seen tons of powdery mildew on deciduous flowering shrubs (Amelanchier, Rosa, Physocarpus) 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] but where the disease pressure is moderate to high, fungicides are not going to be effective. It is getting a bit late in the season for managing this disease. Powdery mildew ovewinters on fallen foliage, blow foliage out of gardens, collect and dispose to minimize disease next year.
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, Ima-Jet, 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.
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.
There are lots of mites feeding on deciduous trees, Ulmus, Fagus, Quercus, Malus and shrubs (Amelanchier, Rosa, Spirea etc.). Usually damage this time of year is inconsequential for tree health.
Taxus or Fletcher Scale NYMPHS have settled on needles and twigs and are feeding. As they become older, they are more difficult to kill with insecticides. Several contact and systemic insecticides are registered for this pest in the nursery.
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 mid-late August should give good knockdown of this next generation of CLM larvae. Cygon is also 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. Click HERE for a short video. 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). Populations in field production and in the landscape are usually not very active until the cooler weather returns in September.
If you are out and about this week, look in marshy areas for several species of dragonflies and damselflies.
This immature male Green Darner was captured on a Canon SX710.
This spring peeper was found in leaf litter below a hemlock/oak/aspen forest near Kingston. Although they are pretty quiet this time of year, they are still pretty cute 🙂