Toronto: April showers and IPM opportunities

Unusually warm weather has hastened the flowering of many trees, shrubs, and bulbs. This also means that insects will become more active. If you want to make this even easier, you can get your free download of BugFinder.

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-purple, that means they haven’t laid their eggs yet. If you can’t see the blue-purple and 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.

Gypsy moth (Lymantria dispar) egg masses are grey from the winter weather but they can be detected on tree trunks, branches (e.g. Acer, Picea pungens, Quercus, Tilia etc.) as well as other wooden objects. Scrape off egg masses, collect and destroy to prevent hatching of hundreds of caterpillars. 

City of Toronto forestry staff have been busy manually removing (yes, that’s a vacuum) Gypsy moth eggs masses from several key oak. Several neighborhoods are slated for Dipel applications to manage this moth defoliator.

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. 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 late fall to trap wingless females, the males they attract and their resulting egg masses. Dipel is registered for larvae in spring.

Read the complete article at www.onnurserycrops.com.


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