Spring is Springing…Again!

Image result for silver maple flowersThere may still be snow in the bush north of Barrie but at long last, its been mild enough to support bloom on several early flowering plants.  Sunday afternoon was heavenly…for a few hours.  It looks like some milder weather is coming mid-week.  Night time low’s will be at or just above 0C in southern Ontario this week.  (Photo of silver maple flowers: Carl Strang, Nature Inquiries).

Where the silver maples are in full bloom, red maples and pussy willow are just beginning to bloom, we are in the range of 1-25 GDD’s Base 10C.





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DCEastSprGallOWFem       Cooley spruce gall and Eastern spruce gall adelgid overwintering females can be found on the undersides of last year’s twigs, next to the base of the needles.  Take a look at these tiny females with your hand lens.  If they are still blue-grey naked nymphs, that means they haven’t laid their eggs yet.  If you can’t see the blue-grey and instead they are covered in thick, white woolly wax…that means egg-laying has started and pesticides will not be as effective.  Insecticides include Tristar, Malathion and horticultural oil.  Be mindful that horticultural oil may remove the glaucus needle sheen on some conifers.

Manual IPM in the Nursery and Landscape:


Gypsy moth (Lymantria dispar) egg masses are greyish-brown from overwintering but they can be detected on tree trunks, branches (e.g. Acer, Fagus, Picea pungens, Quercus, Tilia etc.) as well as other wooden objects.  Scrape off egg masses, COLLECT in a sealed container (or better yet, a soap water bath for 2 days) and destroy to prevent hatching of hundreds of caterpillars per egg mass!  Some arborists and landscapers are vacuuming them off of highly infested trees whose health is at risk of defoliation.  We have some fairly high populations of egg masses in southern Ontario this year!


Overwintering eggs of Fall cankerworm (Alsophila pometaria) are nearly impossible to detect and don’t make very good candidates for manual removal this time of year. (Left image:  http://www.dcnr.state.pa.us, Right image: rutgers.edu). Some horticulturalists report that the egg masses can be smothered with dormant horticultural oil, but the coverage has to be 100%. This is why most horticulturalists use tree bands in the fall to trap wingless females, the males they attract  on tree trunks to help reduce their resulting egg masses.  Dipel is registered for larvae in spring.


Forest tent caterpillar (Malacosoma disstria, above) and Eastern tent caterpillar (Malacosoma americanum) eggs masses are grey and encircle twigs of last year’s growth.  They really glisten in the sun so monitor for these on sunny days before leaf emergence.  Larvae hatch as foliage starts to emerge on host plants.  Prune out, collect and destroy eggs masses to prevent hundreds of caterpillars hatching and feeding on AcerPrunus, Malus, Crataegus.  When larvae hatch, prune out young larval populations during cool mornings or spray foliage with Dipel.


Look for cone-like structures hanging from the ends of branches at this time as signs of Bagworm (Thyridopteryx ephemeraeformis). This pest has been found in the Windsor and Coburg areas.  These “cones” are really overwintering structures that house the female and her hundreds of eggs.  Remove, collect and destroy cones to prevent significant defoliation on host plants (Gleditsia, Thuja, Picea).

VLB Egg mass

Viburnum leaf beetle (Pyrrhalta viburni) egg masses can be found as raised grey-brown bumps, in rows along the UNDERSIDES of last years twigs.  Pick off the raised bumpy cap to see lots of yellow eggs underneath.  Prune out, collect and destroy twigs with egg masses to prevent widespread defoliation of our lovely flowering viburnums this spring.



About Jen Llewellyn

OMAFRA Nursery and Landscape Specialist @onnurserycrops
This entry was posted in Arboriculture, IPM, landscape and tagged , , , , , , . Bookmark the permalink.

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