This table gives the time that pests can be most effectively controlled in New York State. Calendar timing is a broad approximation and applies only to southeastern New York during an average/normal season. Timing will vary for other areas and seasonally from year to year. Use the three timing systems by checking one against the other. Timing systems are not a substitute for scout monitoring.

Table 2.9.1. Pest management timing by calendar, growing degree-day (GDD), and plant phenology indicator (PPI)
Host	Pest	Stage	GDD (Base 50°F)
Dormant Season (usually March or early April): No plant phenological markers offered for dormant season.
Arborvitae	Fletcher scale	immature	20–60
	spruce spider mite	egg	7–121
Azalea	azalea bark scale	adult	NA
Bittersweet	euonymus scale	adult	35–70
Crabapple	European red mite	egg	7–58
Deciduous plants	aphids	egg	7–100
Douglas-fir	Cooley spruce gall adelgid	immature	22–91
Elm	elm bark beetle	larva	7–120
	European elm scale	nymph	7–120
	European red mite	egg	7–58
	lecanium scales	adult	35–110
Euonymus	euonymus scale	adult	35–70
Flowering fruit trees	lecanium scales	adult	35–110
Hemlock	elongate hemlock scale	adult	7–120
	hemlock rust mite	immature/adult	7–450
	hemlock scale	adult	35–121
	spruce spider mite	egg	7–121
Holly	southern red mite	egg	7–91
Honeylocust	lecanium scales	adult	35–110
Juniper	juniper scale	adult/egg	22–148
	spruce spider mite	egg	7–121
Lilac	oystershell scale	egg	7–91
Magnolia	magnolia scale	nymph	22–91
Maple	lecanium scales	adult	35–110
	maple gall mites	adult	50–148
Mountain ash	European red mite	egg	7–58
Oak	golden oak scale	adult	7–121
	kermes oak scale	adult	7–91
	lecanium scales	adult	35–110
Pachysandra	euonymus scale	adult	35–70
Pine	pine bark adelgid	immature	22–58
	pine needle scale	egg	98–248
	spruce spider mite	egg	7–121
Spruce	eastern spruce gall adelgid	immature	NA
	spruce bud scale	immature	22–121
	spruce spider mite	egg	7–121
Tuliptree	tuliptree scale	immature	12–121
White pine	white pine aphid	egg	7–121
Willow	oystershell scale	egg	7–91
Yew	cottony taxus scale	immature	7–91
	Fletcher scale	nymph	20–60
	taxus mealybug	immature	7–91

Delayed Dormant Season, Spring

Pest Management Guidelines A Cornell Cooperative Extension Publication	Cornell Guide for Pest Management of Trees and Shrubs
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